i»: _ _ $5115‘ ‘s wgi?“ , .».. . ‘ .) _ >-\. . ‘ ' b. , a‘ u '- . ‘ ‘ v r _ CONTENTS Acknowledgments ............................................................................................................................................................................... .. Summary and Conclusions ............................................................................................................................................................... .. Blackland Agricultural Area ............................................................................................................ .......................................... .. Soil Erosion .................................................................................................................................. .......................................... .. Land Use Problems .................................................................................................................................................................... .. Methods of Land Management ............................................................................................................................................... ..: Land Classifications for Research and Practice ................................................................................................................. .. The Weather ......................................................................................................................................................................................... The Station ............................................................................................................................................................................................ .. Methods of Investigation .................................................................................................................................................................. .. Weather Records .......................................................................................................................................................................... ..f Small Runoff-Erosion Plots ...................................................................................................................................................... .. Field-scale Runoff-Erosion Plots ........................................................................................................................................... Terrace Gauging and Maintenance .......................................................................................................................................... ..' Crop Production and Land Capability .................................................................................................................................... ' Beef Production in Conservation Systems ............................................................................................................................ .. Land Management ..................................................................................................................................................................... Soil Measurements ...................................................................................................................................................................... Results and Discussion ....................................................................................................................................................................... .. Runoff and Erosion ................................................................................................................................................................... . Relation to Rainfall, Season and Soil Moisture ......................................................................................................... .. Relation to Slope Percent ................................................................................................................................................. .. Relation to Slope Length ................................................................................................................................................. Relation to Crop .................................................................................................................................................................. Relation to Surface Soil Removal ................................................................................................................................... Relation to Soil Characteristics ..................................................................................................................................... .. Relation to Mechanical Factors ................................................................................................................................... ..e Land Preparation and Management .............................................................................................................................. Crop Production .......................................................................................................................................................................... .. Cotton Yields and Root Rot .............................................................................................................................................. .. Corn Yields ........................................................................................................................................................................... .3 Grain Sorghum Yields ........................................................................................................................................................ Small Grain with Sweetclover .......................................................................................................................................... Other Grazing Crops and Beef Production .................................................................................................................. .. l Bibliography ......................................................................................................................................................................................... Appendix ................................................................................................................................................................................................ .. Relation to Slope Length .................................................................................................................................................... Conclusions About Slope Length ..................................................................................................................................... ACKNOWLEDGMENTS Most of the results reported in this bullein were obtained from studies started and supe I H. O. Hill and J. R. Johnston, former station superintendents. All photographs and much of t laboratory data were provided by D. O. Thompson, soil science aide. Physical laboratory soil i ments were made by Floyd W. Robinson, laboratory assistant. Many of the runoff-erosion calcu tabulations and charts Were completed by R. T. Lovorn, assistant farm supervisor. A number 04 co-vvorkers at this station have contributed greatly, both in the accumulation of the basic reco in the development of explanations and interpretations. Much valuable guidance and advice w plied by technical representatives of Soil Conservation Service-Operations and the Texas Agri Experiment Station. A large amount of patient checking, typing and layout work was done Zelda Williams and Mrs. Irma Young. For use on the cover of the air view of the Blackland Ex Station headquarters, We are indebted to C. G. Scruggs, associate editor of the Progressive F SUMMARY AND CONCLUSIONS . Y! enty years of runoff, erosion and related measurements have been completed at the Blackland "ent Station. The present bulletin includes detailed data covering 12 years, together with general information and results to connect it with data summarized in a previous bulletin (18). iii: ly work with terrace design and spacing, lysimeters (which were not successful because of n inkage), gully surveys, infiltration with an artificial rainmaker and soil movement lines was arized in the first bulletin ( 18). Terrace design has been worked out satisfactorily in SCS Oper- ,: practices, and is based on research and experience. The Nichols (drainage) type terrace is stand- "Gully surveys have demonstrated that a primary function of terraces is to prevent concentration off and gully formation. ifiil movement relative to concrete benchmarks showed total vertical movement of 1 inch during ear, for a benchmark sunk to 5 feet, and 11A; inches for a 3-foot benchmark. The entire soil pro- ~» these depths obviously contracts and expands with varying moisture content. Benchmarks sunk :10 and 15 feet have moved less than one-fifth inch. Plowing and other mechanical operations, soil shrinkage and swelling, have overshadowed mass soil movement by erosion (18). h iltration studies showed the effectiveness of straw mulch as well as grass cover in preventing ; e soil sealing and early runoff. With water applied at 3.3 inches per hour, runoff rates greater ~80 percent of the applied rate were reached in all cases during wet runs, after a constant infil- f» rate was reached. For Austin clay, the constant rates varied from 0.25 to 0.59 inch per hour; pr Houston Black clay, from 0.08 to 0.27 inch (18). Under natural rainfall conditions, the mini- " rates for saturated soil probably would be less. 4 enty years of record on small plots and 15 years on field-scale plots show that water and soil I on an annual basis are related closely to total rainfall on land in row crops. With small grain, or grass, the relation is not so well defined. On a seasonal basis, also, heaviest losses correlate otal rainfall, with a peak in May and a smaller peak in September. On row-crop land, losses in Fl April and June, as well as May, are heavier than for the September peak. These relations to rainfall reflect the fact that size and intensity of storms also correlate with total rainfall. Most , have been caused by rains of more than 1.0 inch in 24 hours, and by intensities of more than 1.0 fer hour for 30 minutes. It commonly requires rains of 2 inches or more in 24 hours to cause f runoff when the soil is dry and in a reasonably good physical condition. A high percentage of occurs from small rains of 0.5 inch or less when the soil profile is wet. The fact that most rain i» soil that is dry enough to contain shrinkage cracks is a primary reason for the high percent- 3 water penetration. The land on the Blackland station, especially that in small plots where heavy 3 ery has not been used, is more open to water or roots than much of the depleted Blackland on < enty years of records on small plots, as well as indirect comparisons with large field-scale plots, te that length of slope tends to be a minor factor influencing sheet erosion. Soil and treatment ility, or approximate contouring, normally overshadow slope length effects. Runoff tends to be ly less on long slopes because of the extra time for infiltration. Soil loss per inch of runoff is on long slopes. ‘percent of slope has little effect on runoff but a big influence on erosion. Individual field-scale of varying slope, from 1.39 to 3.01 percent, provide evidence in general agreement with results ‘other locations that erosion increases as slope percent to approximately the 1.4 power. ; e effect of crops on runoff and erosion depends primarily on the amount of cover provided dur- 'tical seasons. No consistent differences between corn and cotton have been shown. Small grains lor with sweetclover have been effective because their heaviest growth gives maximum protec- uring March, April and May, the period of maximum rainfall. With ordinary turning of residues, ' of corn or cotton following small grain has lost as much soil and water as 1 year of row crop fol- i» a row crop. Sweetclovers alone have given good control. Theory and trends in the data favor 3 grain with sweetclover over either crop grown alone. Untrampled Bermudagrass sod in small has given the maximum of water intake and of erosion control. Under pasture conditions, es- y with heavy trampling on wet soil, observations indicate that heavy runoff is to be expected ‘ith dense sod that will prevent soil erosion. Desurfaced soil in plots has lost about 2.5 times as much soil and water as normal soil. Erod, ity of the desurfaced soil has been slightly less per inch 0f runoff than normal soil. Crops that g been grown satisfactorily on desurfaced soil are sweetclover and native grasses with no top growth moved. During 20 years, the desurfaced soil growing native grasses and forbs (including a few voi’ teer native legumes) showed an increase of about 600 pounds of soil organic matter and 30 pound N per acre per year. The build-up was limited largely to the surface 6 inches. Earthworms were v‘: active and contributed to a loose, porous soil condition. ' Differences in workability, available water-holding capacity and subsoil permeability are reco ed between Houston Black clay (SCS Soil Unit 2) and Austin clay (SCS Soil Unit 2X). However, ll ifications by cropping, and the dominant effect of other factors, such as slope, rainfall or cover, H, it difficult to prove any definite relations of inherent soil profile properties to measured runoff erosion. 1 Pore space and bulk-density measurements indicate that the soil in all small plots where heavy f were not used is looser and more permeable than ordinary field soil. Organic matter and water-s ’ aggregates are much higher with grass sod than with continuous cultivation. There are slight org matter and aggregation differences favoring crop rotations over continuous row crops, but most r tions have involved enough row crops to prevent any striking effects of soil-improving crops on the g Available moisture is 2 to 5 percent higher by weight with Houston Black clay than with A . clay. This helps to explain a tendency toward higher yields with Houston Black clay. There is a s, difference in available water favoring rotation and grass plots over continuous cultivation on A .r clay but not on Houston Black clay. Available phosphorus by CO2 extraction remains low in all plots except Bermudagrass on A » clay, where a heavy fertilizer application is indicated. I Repeated applications of small quantiti soluble phosphate appear to be needed for conservation and production. Contouring has consistently shown reduced runoff and erosion in small plots. The effect pro , is less on large plots or field areas where breaks are likely to occur because of imperfect contourin 50-percent reduction in soil and water loss by excellent contouring is suggested on slopes up to 4 cent. Cotton yields have been somewhat higher on contoured plots. I The effectiveness of terraces in the Blackland, where supported by proper cropping, was show early work. Terrace maintenance studies proved that excellent cross sections on Nichols-type te can be preserved by backfurrowing on the ridge, letting the dead furrow fall in the channel, and t ing all furrow slices uphill from the channel to the ridge of the next higher terrace. A satisfac cross section also can be obtained without turning all furrow slices uphill, by letting a second dead , row fall somewhere midway between terraces. However, by this method an undesirable low pla F formed unless care is taken to move the position of the dead furrows in the channel and between races from year to year. An extra backfurrow can be plowed on the ridge when necessary for ll tenance of terrace height. a Through 6 years, stripping on field-scale plots, with a 3-year rotation of corn, cotton and oats; duced both water and soil losses. The effect was greater on 3 percent slopes than on 2 percent. If so, gully erosion was not stopped on the 3 percent slope, thereby emphasizing one important fun * of terraces. Alternate strips of cotton and of oats with Hubam in a 2-year rotation are being us a field practice on the station, but on 3 to 4 percent slopes, rill or small gully erosion has been si , cant. a In early studies, subsoiling showed little effect on runoff (18). Recently, shallow chiselingg been used to break up dry soil enough to permit subsurface plowing. The tools in use for trash-m‘ farming in West Texas and elsewhere, recently have been tested and adapted to Blackland condit’, The surface residues from major crops can be handled effectively, and the influences on water and conservation appear favorable. Deep-furrow drilling of small grain into biennial sweetclover and other hard-ground areas is one of the promising trash-mulch conservation practices for economical duction of grazing crops. High crop yields are an essential aspect of conservation. Cotton yields are highest following with Hubam, oats with vetch, or fescuegrass with one of these early-maturing legumes. These rota i, 4 _il and water and give increased yields. Spacing cotton plants 2 to 4 inches apart in the row is _ practice that favors yields as well as mechanization. Cotton is best adapted to Class I or Class land that has been kept in good condition. Yields and conservation depend on proper land se- i and use. Proper fertilization of cotton with phosphorus and nitrogen on depleted soil increases f and soil protection and makes decreased acreages more profitable. On station soils in rotations ghosphated small grain and Hubam, cotton yields have not been increased by extra fertilizer. p rn and grain sorghum yields with the best adapted varieties depend upon nitrogen, phosphorus ater. Houston Black clay yields more than Austin clay, on the average, because it holds more “Y: water. Crop rotations and practices that put more water in the soil also tend to increase ‘yields. Closer plant spacing in the row, with corn or grain sorghum, has paid consistently and _,~ conservation. Organic matter and nitrogen maintenance with legumes, grasses, fertilization fvy residues help assure high corn and grain sorghum yields and soil conservation. Organic _ levels and trends provide one of the best indexes of soil improvement known for the Blackland. fldistribution in soil profiles is an important normal feature of heavy Blackland soils. f x “K mall grains, especially oats and barley, are key conservation and production crops in the Black- " Improved varieties have increased the yield and quality of grain and helped avoid winter-kill. 1 the past 4 years, the average acre yields of improved varieties of small grain have been prof- Mustang oats, 62 bushels, and Cordova barley, 38 bushels. In addition, these crops are the key l-season grazing in balanced livestock production programs. They also appear important for prop- pervation rotations with row crops. Sweetclovers, the main legumes used in the Blackland, are ent for growing with fall-drilled small grain. ther soil-conserving crops for grazing include Bermudagrass on wet land, buffalograss and KR gem with cool-season clovers on closely grazed or poor upland soils. Sweetclover with Johnson- also has wide usefulness. Mixed native tall grasses, managed for permanence of stand, give gresults. Sudangrass for hot summer grazing is outstanding among cultivated crops. The suc- "J grazing enterprises depends upon putting these several crops together into a well-balanced se- j e that provides good pasturage throughout the year. Grains and hay are a major part of suc- ith livestock. The Blackland can well produce what is needed for wintering to supplement graz- j ops and to fatten livestock to profitable market finish. pparently, Class IV Blackland should seldom, if ever, be used for row crops. It is profitably used phnsongrass and sweetclover, continuous small grain with sweetclover, or permanent grasses and ES. ‘lass III land can continue permanently to grow 1 year of row crop for every 2 years of protection provement with small grain and sweetclover, or grass with clover. Improved residue manage- ' may permit a higher percentage of row crops. p, lass II land, with present farming methods, profits from the improvement of 1 year of small grain sweetclover, or equivalent, for every year of row crop. ‘(Class I land can be used for row crops each year without severe damage by erosion. But the soil ydeteriorate under such cropping unless improved practices are introduced and intensified. These yices include trash-mulch methods, working the soil only when it is dry enough to be firm, ade- e fertilization, close plant spacing of the best varieties and minimum cultivation. With conven- ; management, 1 year of small grain with swe-etclover or alfalfa for each year of row crop main- L high yields on a longtime basis. riThe foregoing estimates for Land Classes II, III and IV are based on an average annual soil loss it more than 2 tons per acre. With higher losses, it is believed that the soil is likely to deterior- ~_nd that stands or growth will be damaged too often for maximum profit. On Class I land the rate is based upon maintenance of surface soil organic matter above 2.0 percent, since favorable "cal properties are possible with 2.0 percent of organic matter. 20" Figure 1. The Blacklund Prairie of Texas. a mmeny of Soil and Water Conservation Rereareh from the Si?’ Blackland Experiment Steltio n, T emple, T exen; 1942-53 R. M. SMITH, R. C. HENDERSON and O. J. TIPPIT* TECHNICAL BULLETIN WAS PUBLISHED in 1944 I arizing erosion, reclamation and related in- ‘ation obtained at the Blackland Experiment _ion at Temple from 1931 to 1941 (18). The nt publication is a sequel to the earlier sum- - . Background information and detailed de- gtions of methods were given in the former tin. BLACKLAND AGRICULTURAL AREA if As shown in Figure 1, the main Blackland _~ 'e extends through Central Texas from the River bottomland on the north and northeast Y: Rio Grande Plain in the San Antonio area he southwest. The distance from north to . is slightly more than 300 airline miles. The includes about/10,000,000 acres. There also ,000,000 acres of Blackland to the southeast, ated from the main Prairie by the forested tal Plain. iThe Blackland Prairie is a rather clearly de- 1 agricultural area. On the east and north ‘he acid, sandy, brown or yellow soils of the ted Coastal Plain. In addition to different I haracteristics in the Coastal Plain, the mix- ,k timber in native habitats emphasizes the ction from the Blackland Prairie. Sparse _ of introduced species mark the Blackland 'e as an area of native grasses, unlike the ; Coastal Plain. {0n the west, the Blackland is bordered by the 1 Prairie and the Edwards Plateau. Much of estern boundary is less sharp than the east- xrder. Yet there are distinct differences of limate and land use. The outstanding, prac- oil difference is depth to rock. In the Black- “ the typical soils provide plenty of depth for 0t development of any crop. But, in the Q Prairie, and to a greater extent in the Ed- »: Plateau, firmly bedded, hard limestone rock fl mon in many soils at depths of less than 18 _ . This rock restricts roots and severely é: the available water supply that the soil can viand provide to the crop. Uncertain rainfall, becomes more of a factor toward the west, “ifies the drouthiness of shallow soils. As _ lt of these factors some of the land in the “ tively, superintendent, farm supervisor and for- . farm supervisor, Blackland Experiment Station, e, Texas. Grand Prairie and Edwards Plateau cannot be de- pended upon to produce consistent yields of most cultivated warm-season crops. Only the deeper soils are directly comparable with soils in the Blackland. Runoff, erosion and production information on the Blackland station at Temple have been ob- tained on deep Blackland soils derived primarily from marl. Similar soils in part of the Blackland area are derived from deeply weathered chalk as well as marl. The Austin clay, shallow phase (Fig- ure 2) on the station may be derived partly from chalk. All soil profiles on the station are deeper than 36 inches over any kind of rock that might restrict plant roots. In most places the soil mantle is deeper than 6 feet. Average annual rainfall at Temple is 34.5 in- ches. Insofar as the obvious soil and climatic fac- tors are dominant, the data and observations at Temple are likely to apply to the Blackland as a whole. However, variables of cropping, manage- ment and inconspicuous soil characteristics in many cases may overshadow the factors of known soil or climatic similarity. It is suggested that specific data at this station be considered as con- tributing to our understanding of trends, relation- ships and principles rather than as precise meas- urements applicable directly to all individual farms, or to a large land area like the Blackland Prairie as a whole. Soil Erosion Unpublished data by the Soil Conservation Servicel indicate that erosion in the Blackland has been serious. The classification by degrees of erosion is: none to slight—5,250,000 acres; moderate — 2,973,000 acres; moderately severe — 3,440,000 acres; severe—-511,000 acres; very severe — 135,000. Much progress in soil and water conservation has been made since 1934 by farmers working with the Soil Conservation Service and coopera- ting agencies, first in demonstration Watersheds and more recently in soil conservation districts. However, erosion and other aspects of conserva- tion still are recognized as major problems in the Blackland area. Many practices have been ap- lSupplied by the State office, Soil Conservation Service. Expanded from direct measurement of field sheets of sur- veys covering 42 percent of the Blackland Prairie. 7 sequence or svnaots 4 Soil types ---/~Soil \--~_,’-Erosion class boundary 2 Erosion class boundary B-+ SOIL TYPES Austin clay Houston black Nustin clay - Austin clay — Austin clay - Trinity clay clay colluvial phase shallow phase deep phase Houston black clay - phase colluvial EROSION CLASSES No apparent erosion 0 to 25% of surface soil removed by sheet erosion 25% to 75% of surface soil removed by sheet erosion 75% or more of topsoil or» all All Recent alluvial of topsoil than 25% of subsoil of topsoil of subsoil deposition Occasional more than laterally O 400 less removed and and 25% to 75% removed or colluvial gullies - gullies I00 feet apart 800' I200 I600 EEEEEEiiiiiiE!!!!!iiiiii!!!!!! Figure 2. Soil types and the degree of erosion on the Blackland Experiment Station. from original map (l8). I\ ._ H Ewv.582 2000FEET 6'13 (ficfifi 7C9? S'Q>_©Q9 Q 4 Q 5'15‘ Hadlfiidi B’ F50 r-dl-db-lfifififiF"(£f'ffl fat help to reduce runoff and erosion losses ‘se have not solved the basic problem of ation in row-crop farming. Land Use Problems _;< data from three counties entirely with- Blackland Prairie, Carter (8) stated that ,1 about 70 percent of the land was used for ' More recent figures by the Soil Conser- jlService show 8,300,000 acres, or 69 per- in cultivation, 3,000,000 acres in pasture 0,000 acres in woodland, or a total of 12,- acres in the Blackland. Cotton is the most a crop (almost 3,000,000 acres), followed age by corn, grain sorghum, oats, barley eat. Most of the row crops are grown fol- other row crops. The acreages of soil-im- .1 crops, such ras clover and perennial gras- ‘rotations with row crops, are very limited. ormally follows cotton, and cotton follows I grain sorghum. Many farms have no :f0r handling livestock. Water supplies for ; k often are limited. The cash outlay re- ‘g for diversified farming with or without ‘k is greater than for strictly row-crop . These are some of the factors that hin- orts toward improved conservation. and use and management changes are known n control erosion and reduce runoff, but i: a demand for new information that will ionservation easier and more profitable for wners and operators. Methods of Land Management e most popular cropping systems and meth- ; se on many farms give little protection to p, during seasons of maximum rainfall. This is a need for better crop rotations, plus ttention to methods of land preparation, f handling, stand establishment, fertiliza- ltivation and harvesting. The damage to hich often is attributed to the crop, may e a matter of the techniques used in crop ion than any bad feature of the crop it- 3 or example, tractor and tool compaction -~ ing or one-way disking of clay soil when w wet, may damage soil structure and in- runoff more than growing an extra year : or cotton with careful plowing at proper '1 e stage. Excessive cultivation or unneces- forking of the ground tends to cause dam- the soil, the crop and the population of ial organisms in the soil. general. practices that favor heavy crop y; and high yields per acre are good conser- g The fertility needs must be established, “y for the soil and the crop rotation, but fit the nature and handling of the residue er cultural practices. Land use and crop a changes are major considerations in per- l. production. However, techniques of land - ent for maximum crop yields and maxi- mum soil improvement are equally important. The Blackland area of heavy clay soils with high pro- ductive potentials, appears to be an excellent lo- cation for conservation through better techniques of land management. All practices that favor ease of tillage, optimum crop stands, higher wa- ter intake, increased water storage, adequate aer- ation and balanced nutrition are keys to conser- vation and permanent production. Larnd Classifications for Research and Practice The Soil Conservation Service recognizes land classes relative to slopes for the major deep up- land soils, as follows (22) : Class I, 0 to 1 percent; Class II, 1 to 3 percent; Class III, 3 to 5 percent; and Class IV, 5 to 8 percent. The upland soil units to which this classification applies include soil unit 2—-deep, fine textured, slowly perme- able soils: mostly Houston Black clay, and soil unit 2X—deep, fine textured, permeable soils: mostly Austin clay. Soil unit 4—deep, fine tex- tured, slowly permeable bottomland soil—is ra- ted the same as soil unit 2, except that some areas overflow or suffer from poor drainage and, there- fore, are placed in Class V or VI. , Where lime contents are low in Blackland soil and in mixed soils of the Blackland border, soil unit 1 occurs — deep, fine textured, very slow- ly permeable soil: mostly Wilson and Crockett with clay loam to clay textures. The tightness of soil unit 1 causes eroded areas on slopes of 1 to 3 percent to be placed in Land Class III, instead of Class II as with soil units 2 and 2X. Moreover, Class IV includes soil unit 1 on 3 to 5 percent slopes only, whereas with soil units 2 and 2X, and moderate erosion, slopes from 5 to 8 percent, are included in Class IV. There are narrow bands of shallow soils over chalk or limestone, and steep, broken land along stream breaks in the Blackland. This land is ra- ted Class VI and Class VII, suitable only for per- manent vegetation. The acreage of non-tillable land has been increasing because of severe gully formation on knobby hills and on slopes border- ing entrenched streams or along the distinct es- carpment that forms part of the western edge of the Blackland. The following acreages of the different land classes have been determined by the Soil Conser- vation Servicez: Class 1—2,265,000, with 1,800,- 000 acres cultivated; Class II—5,000,000, with 4,400,000 acres cultivated; Class III--2,240,000, with 1,110,000 acres cultivated; "Class IV — 720,- 000, with 346,000 cultivated; ClassV—882,000, with 216,000 acres cultivated; Class VI—254,- 000, with 165,000 acres cultivated or idle; and Class VII — 740,000 with 229,000 acres cultivated or idle. 2Supplied by the State office, Soil Conservation Service. Expanded from direct measurements of field sheets of surveys covering 42 percent of the Blackland Prairie. LAND CAPABILITY MAP BLACKLAND EXPERIMENT STATION FARM TEMPLE, TEXAS 0 I000 2000 3000 1i fi | FEET ;“ Q: ti" . - kL. LEGEND Land Suitable for Cultivation m with few or no permanent limitations J I and does not have hazards to the main— + - tenance of the land. with slight permanent limitations or I1 moderate hazards to the maintenance of xe the land. ‘R with severe permanent limitations or Di frequent hazards to the maintenance of the land. .. C) with very severe permanent limitations §§" 1 - m or very frequent hazards. lt may be cultivated only between long time or irregular periods of permanent vegeta- M _ tion or may be used for limited culti— " " vation. - \\ Land Not Suitable for Cultivation Suitable for permanent grasses with 33 few or no permanent ilmJtatl0flS, or slight hazards. Soil Units, Blackland Problem Area in Soil Conservation .\\\W 2 Deep, fine textured, slowly permeable soils Ziilll 2x VIII/z. M Deep, Deep, fine textured, moderately permeable soils fine textured, slowly permeable bottomland soils Figure 3. Land capability map. Blackland Experiment Station Farm, Temple, Texas. Fpgg-gp-“Qqgqh-gpfitgpnp-Q-L-Jhq i-I-iv-(I-(r-FL-Lrflb-Iaqaq bility units determined by soil, slope p, ion are a primary basis for much research conservation planning. The units recog- _ the station are shown in Figure 3. This _ tion is based 0n relatively permanent . Temporary physical or fertility condi- y vary widely within capability units and i considered in specific interpretations or Greater detail of soil types and eros- A 'ven in Figure 2. THE WEATHER re 4 presents a Weather summary on a ‘ basis for 40 years of record at Temple. "5 shows total annual rainfall relative to n of 34.5 inches. During the period 1947- Qannual rainfall totals were below the 40- iean. This may emphasize moisture defi- more than is justified over long periods. ‘Pr, with an average frost-free season of “s-(March 17 to November 21) and high A summer temperatures, severe drouth per- f inevitable, even in years of normal rain- Vvaporation (Figure 4) and water use by xceed rainfall from mid-June until Sep- Long dry periods are common. Average I I I I Rainfall Evaporation Wind \ Average maximum temp.“ 0 B> X I 0 - Average minimum temp. / \ / / /'7 /‘ /. i/ r/ ,\\7 \ \ \ \ 3, 1x 3 I I 1/ /— _/ RAINFALL AND EVAPORATION - INCHES 1 Y;Peb.Mar. Apr. May June July Aug.Sept.Oct. Nov. Dec. e 4. Summary of certain weather iactors at Temple ‘N, thly basis, 1913-52. open pan evaporation for June is 6.9 inches, July, 7.9 inches and August, 7.9 inches. Rainfall for these 3 months averages 2.9, 1.9 and 1.9 inches, respectively (Figure 4 and appendix tables.) Wind movement averages about 5 miles per hour during the summer and slightly more in win- ter and spring. Even though average summer Wind movement is lower than spring, strong dry summer winds contribute to drouth damage. If average evapotranspiration for good crops is estimated as 0.6 times open pan evaporation (24), summer need for water is seen to be great- ly in excess of rainfall. On this basis, evapotrans- piration for normal crop growth is 13.6 inches for June, July and August, as compared with the aver- age rainfall of 6.7 inches. Water use by crops calculated by Blaney et al (4, 5) indicates that 6.7 inches of summer rain- fall is inadequate. For cotton, which is rated as using less water than many crops, the use for June, July and August is 15.2 inches. For grass pasture, a high user, it is 18.4 inches. These’ cal- culations are based on average temperature and daylight hours. As shown by Figure 4, open pan evaporation correlates closely with average tem- peratures. Other factors, such as wind, may be important but they do not alter greatly the aver- age temperature-evaporation relationship. Another consistent feature of the weather at Temple is a moist or wet period during March,’ April or May. During this season, the soil nor- mally is permeated with water t0 at least 3 or 4 feet on all land that has a reasonable intake ca- pacity. One exception was 1950, when the soil probably remained dry below about 24 to 30 in- ches. Often there is a surplus of water at some time during the spring. This is the time of high- est annual runoff and erosion. Relative humidity commonly goes as lowas 30 to 40 percent during hot, dry days in midsum- mer. In winter and spring, the relative humidity usually approaches 100 percent at night and about 70 percent in midday. THE STATION The Blackland Experiment Station is located? 2 miles south of Temple. In addition to studies of conservation and land use, the work includes corn breeding and production; cotton root-rot con- trol, production and mechanization; forage crop testing and management; small grain testing and management for grazing and grain; variety test- ing of all common Blackland crops; beef cattle grazing and management; and supporting labor- atory work in soils, microbiology and pathology. The overall station farm layout is shown in Figures 7 and 8. These two maps indicate how field arrangements haveubeen shifted to provide improved land use in accordance with land capa- bility, and to favor utilization of soil-conserving Ll RAIN- FALL INCHES ANNUALLY "5? ANNUAL RAINFALL l9l3-I953 FROM RECORDS or BLACKLAND EXPERIMENT STATION, TEMPLE TEX. 50 ‘l5 40 i 3-5 30 ! _____2! 25 9 20 5E1 __——._—__— _——___ 511E] ___—— 8131-1 20.1 ——__ 27o ——_— 41.11 _——_——_ BET-l _—__— EEIIII __—__ KIRK-i m :9- nn ~o r~ a) O~ o 1-1 N m :9- nn ~o v- a) t» 1-‘ Fl Pi I-i I-‘l 1-1 Fl N N N N N N N N N N 0* U‘ C‘ 3* 0* 0* 3* C‘ 0* O\ 0* O‘ U\ 3* 6* 0* O\ v-i 1—( r-i r-i 1-1 r-l r-l 1-1 1-1 1-1 r-l 1-i 1-i 1-1 1-1 1-1 1-'l Figure 5. Annual rainiall. 19413-52, crops by grazing cattle in a year-round program of beef production. Land character is shown in Figures 2 and 3. Total area of the farm is 542 acres. Head- quarters areas, houses, yards and roads occupy 40 acres. The main permanent pasture along Boggy creek (north and south of road) contains 44 acres, part of which is Class V land that is too wet for practical cultivation. The land in peren- nial grasses with clover totals 83 acres, or 16 per- cent of the farm. Long-time plot layouts amount to 30 acres (including large runoff-erosion plots o! steer gain per acre. l2 1930" Nt\‘\:I'\L\~OI~wO\O1-INR\:I'IG~OI~QO\OH mmmmmmmrrxs-zra-a-s-s-zrn-zrzrmm O\G\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\O\ r-lr-lr-lr-lr-{Hr-lrtr-ir-lr-lv-ir-iv-lr-lr-ir-iv-IHH irom records of Blackland Experiment Station. Temple. Texas. Figure 6. Permanent grass pasture is good land use and is profitable on bottomland that is too wet {or dependable ping (Class V land). Bermudagrass with cool-season annuals gives a long grazing season and returns oi more than 150 -- AvL-yl-s i III I —__— ___z=...=II 29.00 20 5E1] EHIEE N Ni ii my KEEN‘! q O and P). Various short-time plot experim are superimposed on field areas and on the w runoff-erosion plots, providing realistic situat for obtaining plot results. ; Field-crop rotations and techniques are n; sarily changed in accordance with progress by search and practice. Figure 8 shows the ” rotations and land use in effect in 1953 near-v end of the period covered by this report. ‘A pattern is quite different from the Blacklan a Whole, Where standard cropping is often t, cotton, grain sorghum, in large rectangular fi with no grassland or livestock. l I ‘\_I ' at ,*\_ Field s-z Field N l I .' | I l, U 500 1000' 1500 2000 feet | \\\ _ I i n 1 l J b \ \ . U I \ a I \ ' I ‘J-‘icid ST I Q I \\ \""\\ N I 7 G 5 4 3 2 Raid T || \\\ : 2 U C ___'—-- ——-—-_“_" | Fl C id R \: 3v? E‘ l) _ a \ a R [j-"j —_ -—‘ "{'@6g@ lg ii’ é t: .t____.. i C5) —_ " ' i3 ‘is // w I @ pa. i i ‘ \\ ' I ~' Cit‘ _ _ - i .__. __-___. l/ i; "l i; l; @ LEGEND ' L f “s Headquarters Buildings - Federal and State // _ _ Pasture ____ l‘ Q Q/ s:_.9‘ . i .. _ __ \_i y ‘i: is‘? Soil Conservation Control H“ ________ -—-—'-1~_{.-'E-L7 {its g _ §= Plots 4% Slope I l(’17l¢|d/%” g‘ Mir/GD v Grass Test Plots l‘ Lffix i, "i \ \\ (Nova ‘c: Soil Conservation Control \\ 3)“\‘_ __.;.____= V’ _ _ _ _ _ _ ___\ u ";.‘.‘:'.'_'.---— _Plots 2% Slope \,\ Vi»? G,- // > ‘#@v/ 1 / Agronomic Field Studies ‘IQ?!’ Fifild Q [loot Rot and Plant Disease | '-\\ i Investigations I‘ -,_\~—:_-_-::- Soil Conservation Field Size . T s N 3h ve Meadoi-xi’ Control P,lots _____ __ i k Field Strip Cropping Studies Q i‘! A Terraces With Strip Cropping Studies fi Revegetation Studies on Eroded Area l i Livestock Land Utilization 2 c» Figure 7. Blcrcklcmd Experiment Station Farm. Temple. Texas. 1942. l3 State Field Series '7 6 5 4 3 2 1 t ==__ — WK IIIMIIII 3d K [I] 6c E A L_AJL4Ln #3 68 6b EIKJEIKIL o [In F < 5 EIEJIIII F1 a F1 [-10 r" J, LEGEND 1, la, lb, lc and ld. Smallgrain (o), annually. 2a and 2b. Two year rotation of corn, oats (c). 3a, 3b and Sc. Sweet sudan, barley (0), barley (c). 4. Cotton, oats (c). 5a, 5b and 5c. Barley (c), barley (c), grain sorghum. 6a and 6b. Corn, cotton. 6c. Corn breeding, oats (c). 7. Annual grazing of native grasses. 8a. Johnsongrass for grazing, in rows. 8b, 8o and 8d. Annual grazing of warmrseason grasses. 8e. Warmvseason grass lane. 8f. K.R. bluestem.with cool-season clovers. 8g. Johnsongrass and sweetclover. 9a. Fescuegrass with sweetclover lane. 9b. Fescuegrass with sweetclover and alfalfa. 10. Odd areas for hay or smallgrain. A. Small plot studies. C-15, C-14, C-15 and C-16. Corn, oats (0): tillage, terrace, 0 runoff studies. C-1 to C-7. Smallgrain-sweetclover-Johnsongrass. L, L—l, L-2, L-5 and L—4. Tillage, terrace studies. O-l to 0-6 and P-1 to P-6. Field scale runoff-erosion plots. C-'-"""'“’3 Q - Building. Note: (0) - Annual or biennial sweotclover. “_ ewga &,, u i Q“ u i 1000 0 1000 2000 Feet ‘gee M" “ ~ u? w» W Figure 8. Blackland Experiment Station Farm. Temple. Texas. 1952. 14 w .7 w .-'/' ‘Y? .1. h METHODS or INVESTIGATION l Weather Records i‘ j ount and intensity of rainfall have been ied with Fergusson recording rain gauges } immediate area where runoff-erosion re- ave been obtained. Standard U. S. Weath- eau gauges also have been used at each lo- ’. Temperature, wind and evaporation have f: easured by standard U. S. Weather Bu- methods. Barometric pressure has been f?» with a Taylor anaeroid barometer and Friez recording barometer. Relative hu- t measurements have been made with a Friez ping hygro-thermograph, as well as with d dry thermometers. Details of rainfall, rature, wind and evaporation are shown in dix tables. Small Runoff-Erosion Plots at e complete list of small runoff-erosion ; given in appendix Table 17. These con- glof one layout of 16 plots on slopes of 31/2 rcent and one layout of six plots on a slope rcent. The steeper slope was on Austin oil (SCS Land Class III-2X) , and the 2 per- lullots were on Houston Black clay (SCS Land I-2). easurements of runoff and soil loss from ‘plots No. 1 to No. 11 of 1/200, 1/100 and acre were made volumetrically. The total i from a plot was caught in a concrete tank lower end of the plot. Samples were taken sludge after the water was drained off. The ty of soil lost from the plot was determined ,1 he oven-dry soil content of these samples. Silt boxes and Geib divisors were used for ing losses from intermediate-size plots to No. 25 (18). Field-scale Runoff-Erosion Plots pihese measurements, which are being con- , consist of 12 plots of 1.5 acres each. Type v {Z0 years. H measuring flumes, developed by the Soil Con- servation Service Hydraulics Laboratory, are used for determining rates and amounts of run- off. The soil loss in runoff is obtained by means of silt boxes, Ramser silt samplers and Geib di- visors (18). Terrace Gauging and Maintenance Surface runoff has been obtained from ter- races by means of Parshall flumes equipped With automatic water-stage recorders (type FW-1, Friez). During recent years, no soil loss meas- urements have been made from terraces. Terrace maintenance studies included com- parisons of terrace cross-sections obtained by dif- ferent methods of plowing. With the standard method, a backfurrow was placed on the terrace ridge, a dead furrow in the channel and all of the soil above the channel was plowed uphill. A sec- ond method consisted of backfurrowing twice on the terrace ridge, leaving dead furrows in the ter- race channel and midway between terraces. In earlier work with the standard method, uphill plowing was not practiced. This left a dead fur- row midway between terraces. Subtillage or trash-mulch plowing of terraces recently was com- pared with the standard method. In studies of terrace maintenance, detailed cross-sections were charted at 1 or 2-year intervals. Crop Production and Land Capability Field-scale trials of promising. crop rotations or improved practices are an important part of the experimental approach at the Temple station. Yields of corn, cotton, grain sorghum and small grain have thus been determined on different land capability units. Observations also have been made of field runoff and erosion. Conclusions regarding productivity of crop rotations and prac- tices, and the degree of runoff and erosion con- trol, therefore, can be based upon experiences from field-scale operations as well as from small plots. e 9. Runoff-erosion plots on 4 percent slopes. Plot 3, continuous corn. shows a sealed-over surface compared with here Hubam stubble has been spaded. The soil level in Plot 3 is about 3 inches lower because of heavy erosion losses 15 Beef Production in Conservation Systems The return from soil-conserving forage crops was evaluated by beef production 0n various fields for a number 0f years. Profitable year-round grazing has been the goal of these forage crop management studies. All phases of practical beef cattle grazing and feeding were considered to de- termine whether beef production can be‘ fitted into Blackland conservation farming. Emphasis was placed upon proper stocking and grazing by crop, soil and season. Conservation and profits were observed and compared with results from cash crop farming on different kinds of land. Land Management Techniques of land preparation, including trash-mulch plowing, fertilizer application, stand establishment and harvesting were extensively tested under Blackland conditions, and in con- junction with crop rotations, terracing, contour- ing and strip cropping. Conclusions on the effec- tiveness of techniques are based primarily on ex- perience and observations, but are supported by certain small plot data, field crop yields, stand counts, residue measurements and soil determina- tions. Soil Measurements Soil profile samples to a 3-foot depth were collected from all small runoff-erosion plots, from the 12 field-scale runoff-erosion plots (O and P plots) and from various field areas. These sam- ples were used for determinations of organic mat- ter (7), bulk density and pore space, moisture tension relations and available moisture holding capacity, soluble nitrates (25), total nitrogen (Kjeldahl method—selected samples only), aggre- gate stability (27, 32), calcium carbonate equiv- alents, and readily-extractable phosphates—CO2- soluble (14). RESULTS AND DISCUSSION Runoff and Erosion Relation to Rainfall, Season and Soil Moisture The average monthly runoff and erosion from plot 3, continuous corn, is closely related to total rainfall (Figure 10). This tends to be true for all plots with light vegetative cover. Intensities as well as monthly quantities of rainfall correlate closely with runoff and erosion losses. It is difficult to separate quantity and in- tensity features of rainfall in monthly or yearly averages. The quantity of water usually is too small to cause serious losses unless intensities are high for periods of 3O minutes or more. Rains of 1.0 inch or more, and intensities higher than 1.0 inch per hour for 30 minutes, cause most losses (appendix Table 16). When rainfall reached 2 inches or more in 24 hours, usually there was some runoff and erosion on row-crop land at Temple. 16 Month Jan. 2 A Feb. Mar. 5 I Apr. May Z June July \ Aug. Sept. Oct. Nov. Dec. HPQUYHQWQBQA INCHES No. of Years. with Runoff l \ RAINFALL "A 3 A RAINFALL OR RUNOFF - M i -—""' i Z "l/A \ v A!’ SOIL LOSS 1 \ RUNOFF --*%/ ’ / \ /A\ /’1§:"' /- / 1:1. ’, *~_\__ —~,_ Jan. Feb. Mar. Apr. May 7.15; July Kg. Sept. Oct. Nov. Figure l0. Average runoff and erosion by mo i plot 3. Austin clay. 4 percent slope. in continuous corn. in relation to rainfall. Results are for ‘the llJ-year 1942-51. When the soil is dry and in good condition, iti more than 2 inches in 24 hours to start run; Soil and Water losses from row crops, _ annual basis, are closely related to total a“ rainfall as shown by Figures 11, 12 and 13. off has been insignificant with ungrazede mudagrass on small plots. With small gr field-scale plots O and P (Figures 11 an) there were years when runoff and erosion ed little relation to total rainfall. The ex tion was rainfall distribution. Small grain, excellent protection during April and May. ever, during the fall, losses are likely to c0 with rainfall characteristics on small gra Well as on row-crop ground. At that timi land is plowed and unprotected by vegetati J Figure 11 shows that normal annual from row-cropped Blackland on 2 to 3 5|||I| I Corn X Cotton O Oats or oats with clover Q I RUNOFF - INCHES >< o 0o a: f6 o o s 1o 15 2o 2s so as 40 ANNUAL RAINFALL - INCHES Figure ll. Ten years (1942-51) of runoff on fie plots. O and P. in relation to total rainfall. Crops re ' are corn, cotton and oats. There is a close relation , runoff and rainfall for corn and cotton. but much less l with oats. -‘ if O Corn X Cotton '_-0 Oats or oats with clover ‘D o o l\ f\ o- 0 ° 61241 n ° €~5 10 15 20 25 80 35 40 45 50 ANNUAL RAINFALL - INCHES '10 12. Ten years (1942-51) of soil losses on field- ts O and P, in relation to total rainfall, for corn, d oats with clover. There is less relation between and rainfall with oats than with row crops. - iis about 2.5 inches for years with an aver- ilnfall of 35 inches. Average soil losses for e conditions are about 4 tons per acre. 0' mple hydrographs (Figures 14, 15, 16 and trate the effect of soil moisture on run- __th two types of surface soil conditions on 1 le plots. The 2.0-inch rain on moist soil d in runoff of 0.68 inch from corn after i (Figure 14) and 0.36 inch from corn fol- fescuegrass sod (Figure 15). Losses of were much heavier from the 1.66-inch rain llowed, amounting to 1.08 and 1.15 inches, ively, for the two plots. This was about 'rds of the total rainfall. There was a 15- peak rainfall intensity for the second rain inches per hour, as compared with a peak inches for the first rain. Even so, the big- ifference in runoff evidently was a result wetter soil with a slower infiltration rate the second rain. Two plots of excellent ith sweetclover and four plots of fescue- "iwith sweetclover showed only a trace of from these same storms. The most im- treason was soil dryness. The plots with and sweetclover were almost at the wilting point. There was room for intake and storage of 1.7 inches of water per foot, as compared with only 0.3 inch per foot for the moist soil of the corn plots. In addition, on corn plots there may have been significant compaction layers, or “ploW- pans,” limiting the rates of infiltration. During the first rain, there was a delay in runoff and a reduction of total runoff for the plot with residue of grass sod amounting to about 0.3 inch. This appeared to be caused by the open, im- mediate surface layer provided by the residue of grass roots and sod fragments or clumps. How- ever, on wet soil where some soil layer below the immediate surface evidently was limiting water intake, the sod residue failed to reduce runoff. In both cases, there was much less soil loss from the plot with sod residue. Total losses were 6.8 tons for corn after cotton and 2.4 tons for corn after sod. The 6.8-ton loss is one of the heaviest from field-scale plots for a single storm period. Observations indicate that the difference resulted from the binding action of the masses of fine, fibrous fescuegrass roots holding the soil together and preventing its removal. Relation to Slope Percent Field-scale plots O and P provide an oppor- tunity to check the effect of slope percent on eros- ion, within the slope range from 1.39 to 3.01 per- cent. There is no consistent relation of runoff volume to slope percent (see appendix tables). Figure 21 shows average soil loss per inch of runoff for each of the 12 field-scale plots in rela- tion to slope during all years the plots were in corn lO 9 o o ' 8 O Continuous corn ll I w X Ungrazed Bermudagrass m '7 Z <2» . I» _ 6 I :- s g o o j o _, 4 e ' 4 = O z o l‘ a I o o ' 2 1 e . X 1i X Vin/r‘! xxvy XX X g X XX 5 1O l5 2O 25 3O 35 4Q 45 5O ANNUAL RAINFALL - INCHES Figure 13. Relation between total rainfall and runoff from plot 3, in continuous corn. Records cover 1931-51. Com- pare with low or insignificant runoff from continuous, un- grazed Bermudagrass, plot 6. 17 INCHES, PREVIOUS RAINFALL Previous rain within 48 hours - ~'_ inches, With no runoff and no l % rain since April 29. 1' ""-'-"-" Runoff intensity Total rainfall for April - 2.53; Rainfall intensity -o——-o- Rainfall amount o O 0 o o Runoff amount inches- SOIL AND CROP CONDITION. Surface soil condition - normal, t cultivated, moist. Very light; residue of cotton stalks. Subsoil moisture - medium moist. “ I/ Crop — corn, plants spaced 15 in “"" I \ in 42-inch rows, 2'7 inches tall \ Previous crop - cotton. , \ Runoff from this 2.0 inch rain -1 \ 0.68 inches. \ Approximate soil loss - 2.6 tons; - INCHES PER HOUR RUNOFF I—* Average infiltration from 1200 p to 3:00 pm = 0.66 inch per hou_ RAINFALL I I I ’____,....-0-——-0——0——-o-——/ |I 0 \ I ” / I C \ L‘ 2 I . 0 I -——'“~’o ' l0 ll 12 1 2 3 4 am am n pm Pm pm pm TIME Figure 14. Hydrograph for a storm of 2.0 inches falling on May 12. 1953 on moist soil of field-scale plot O-1, grow‘ following cotton. Plot slope. 2.31 percent. 3 PREVIOUS RAINFALL Previous rain within 48 hours - inches, with no runoff and no 0_ rain since April 29. “I -9—-—'9- Rainfall alwunt .._ Total rainfall for April - 2.53 inches. Rainfall intensity ———-- Runoff intensity 2 °° °°° Rm“ a"‘°““‘ sou. AND CROP CONDITION‘ I Surface soil condition - normal, -p cultivated, moist. Abundant so‘ clumps. ’ Subsoil moisture — medium moist. - INCHES PER HOUR Crop - corn, plants spaced 15 incl / in 42-inch rows, 2'7 inches tallv ' Previous crop - fescue grass and I sweetclover hay. N? Runoff (total) — 0.36 inches. Approximate soil loss - 0.6 tons. ‘ RUNOFF I-‘ Average infiltration from 1100 pm I 3:00 pm = 0.82 inch per hour. RAINFALL - INCHES, P 1O ll 12 l 2 3 4 am am n pm pm a pm pm TIME Figure 15. Hydrograph for a storm of 2.0 inches falling on May 12 on moist soil of field-scale plot O-3, growin following grass sod. " 1 on. Soil loss per inch of runoff is chosen easure of tendency to erode in order to help ate natural soil infiltration differences i: plots, and to help equalize differences years. When studied in this manner, the * show a characteristic increase in soil loss ‘increasing slope. The data show a reason- it to the curve Y = 0.5K“. The exponential "e of the curve has some theoretical founda- hand the exponent 1.4 has been established ‘a: from various locations (33). The present jwould not be conclusive if unsupported by _ and by other empirical results. However, _sults are in general agreement with the ac- ,‘ relation between erosion and slope. 'on to Slope Length The result of slope-length comparisons on _~ plots are summarized in Table 1 and Fig- 1.22. The longest period, 21 years, involves plots only. For 13 years, three plot lengths compared? ‘iappendix- page 39 for further evidence and discus- regarding s-lope length. Relation to Crop Tables 2, 3, 4 and 5 and Figures 10, 11, 12 and 13 show crop and crop-rotation effects on runoff and erosion. Greater detail is given in ap- pendix tables. Figures 23 through 34 give an- nual results for each of the large, field-scale plots. There is no clear evidence of any difference between row crops, corn and cotton, as they in- fluence runoff and erosion. Neither crop gave much protection during the critical months of March, April, May and September. Losses dur- Table 1. Summary of results on three continuous corn plots comparing the effect of length of slope on annual runoff and erosion on Austin clay‘ Average for 13-year pgiod. 1931-4? Soil loss Slope Runoff. Soil loss. per inch Plot Length percent Rainfall inches tons per acre of runoff 1 36.3 4 32.4 5.3 20.6 3.9 ' 3 72.6 4 32.4 4.6 19.3 4.2 2 145.2 4 32.4 5.8 18.4 3.2 Average for_21Ayears, l931;51 1 36.3 4 32.8 5.3 14.5 2.7 3 72.6 4 32.8 4.8 16.0 3.3 1 There is no clear evidence that slope length is an important factor in influencing runoff or erosion. PREVIOUS RAINFALL Previous rain within 48 hours - 2.97 inches. Total rainfall for April - 2.53 inches. SOIL AND CROP CONDITION Surface soil condition - packed, wet. residue of cotton stalks. Subsoil moisture - medium moist in lower subsoil; wet above. Very light Crop - corn, plants spaced 15 inches in 42-inch rows, 2'7 inches tall. Previous crop — cotton. Runoff from this 1.66 inch rain — 1.08 inches. Approximate soil loss — 4.2 tons. Average infiltration from 3100 pm to 5230 pm :' 0.28 inch per hour. ’ Rainfall intensity +————0- Rainfall amount ——-——- Runoff intensity o o o opo Runoff amount e 16. Hydrograph for a storm of 1.66 inches immediately following a storm of 2.0 inches on May 12 K, growing corn following cotton. Plot slope. 2.31 percent. ' '7 pm on field-scale 19 3 PREVIOUS RAINFALL Previous rain within 48 hours — 2.97 inches Total rainfall for April - 2.53 inches. o: :: g SOIL AND CROP CONDITION Q: Surface soil condition - packed, wet. Abundant sod u: clumps. Q‘ Subsoil moisture - medium moist in lower subsoil. ‘u’: Wet above. :: Z Crop - corn, plants spaced l5 inches apart in 42-inch “' rows, 27 inches tall. I 2 Previous crop - fescue grass and sweetclover hay. u_ Runoff from this 1.66 inch rain - 1.15 inches. g _1 Approximate soil loss - 1.8 tons. 2: Z Average infiltration from 3:00 pm to-5Z3O pm = 0.22 ///‘fll inch per hour. ml - f 2: | 7: e u -—~ 2: I‘ , I ‘ <3 o o o O 0 I ¢° j 1 |' l 0 o I “<- I l p/ I o o“ ---—- Rainfall intensity f fi p‘ 0° ——1 —O———0- Rainfall amount < I I b0 A , ——-——- Runoff intensity Q: 1 0‘ l\ ‘1 o; / \ O 0 0 o .0 Runoff amount <>\ / \ o u / \ I \ g O \! \ / , o \ \ 3 O . I Q d L1 \__. O £ZO L 3 4 5 6 7 pm pm pm pm pm TIME Figure 17. Hydrograph tor a storm of 1.66 inches immediately following a storm of 2.0 inches on May 12 on field-sol 0-3, growing corn following grass sod. Plot slope 2.08 percent. , '3 ing June and July undoubtedly are reduced by fall. The condition after spading in 1948 is s corn or cotton growth, as compared with fallow in Figure 10 and the data are given in Ta land. In 1953, with fescuegrass and subsurface j Soil and water losses with small grain or with sweetclover, or a combination of the two, are small. This is shown by the small plot and the field-scale plots and is substantiated by nu- merous observations on field areas. Two-year crop rotations of row crops, small grain with sweetclover, reduce overall soil losses to only slightly more than half that from continuous cul- tivation to row crops. It is commonly thought that a row crop after small grain with clover tends to lose less soil and water than a row crop following a row crop. However, the data do not prove this (Table 5). When residues are turned under, the big effect of small grain with sweet- clover is obtained while this soil-conserving crop combination occupies the ground. Hill et al (18) noted this in earlier records. Figure 18. Heaviest soil and water losses on - ' scale plots are obtained with cotton or corn. The mu A carryover effect Wlth cotton was noted represents 7.9 tons per acre washed off by 7.7 inchelx fPQm 1946 thrmlgh 1949 when Hubam was grown during 4 days in May 1953. The plot is planted ta to maturity and spaded into the ground in the following corn. Runoff was 3.3 inches. 20 gure 19. Compare with Figure 18. Oats with sweet- lost only 0.1 inch of water and a trace of soil from inches oi rainfall in May 1953. Adj/there appeared to be a carryover effect of J into the corn year (Figures 14, 15, 16 and ree “Relation to Rainfall, Season and Soil ure”). More records are being obtained to p ine the consistent magnitude of the sod in- jce. Studies at other locations indicate dis- ; carryover effects in crop rotations (6, 23). IBoth soil and water losses have been insig- nt from small plots of ungrazed Bermuda- ' on Houston Black clay and on Austin clay. Y from grazed Bermudagrass pasture (2) and ations indicate that the losses of water un- litatural Bermudagrass pasture conditions may nsiderably higher than from the small plots, are loose and porous from roots, earthworn ‘n and the absence of compaction. lion to Surface Soil Removal Plot 11, 4 percent slope, from which 15 in- iof surface soil were removed, has continually more water and soil than comparable plots l normal soil. Table 4 (see “Relations to ") shows that from 1945 through 1949, plot tan average of 5.1 inches of water and 10.1 10f soil, annually, as compared with 2.1 in- Lof water and 4.1 tons of soil by plots 2 and l three plots were in a 2-year rotation of n, Hubam sweetclover. During this period, ' aced plot 11 lost 2.5 times as much water toil as the normal plots. Soil loss per inch off, or erodibility, was essentially the same j e desurfaced and the normal plots. During it‘. years, the desurfaced plot lost less soil ch of runoff than did the normal soil. Heavy ,sses have been caused by greater runoff the desurfaced soil. And greater runoff, n, is at least partly caused by lower water f: capacity in the desurfaced soil. As shown ble 4, desurfaced plot 11, in the 2-year rota- f cotton, Hubam, lost slightly more water lightly less soil than plot 3, in continuous or plot 14, in continuous cotton. On two other plots from which 22 inches of surface soil were removed in 1932, an indication of the rate of soil rebuilding has been obtained. The soil was Austin clay on a 31/2 Percent slope. One plot was established in mixed native grasses‘ and forbs while the other was maintained in culti- vation. During 20 years, the surface 11/2 inches gained about 1.3 percent organic matter; the sec- ond 11/2 inches gained 0.8 percent and the next 3 inches gained 0.3 percent over. the adjacent de- surfaced plot kept in cultivation. The gain amounts to 6 tons of soil organic matter, or ‘600 pounds of nitrogen per acre, which is 30 pounds of N per acre per year. The final organic matter and nitrogen percentages by depth, after 20 years, are given in Table 6. Under grass, there was only a trace of or- ganic matter build-up below 6 inches. The total of 1.3 percent at 6 to 12 inches is only slightly above that in adjacent desurfaced soil under cul- tivation. The accumulation of 30 pounds of N per acre per year represents the nitrogen obtained from non-symbiotic fixation in the soil, from rainfall and from symbiotic fixation in root nodules of sparse native legumes associated with the grass. Adjacent cultivated plots with normal soil contain between 2.0 and 2.4 percent of organic matter in the surface 6 inches. Plot 6, in Ber- mudagrass for 20 years, contains 3.5 percent or- ganic matter in the same depth. Relation to Soil Characteristics Major soil characteristics as recognized in this area are rated in Figures 36 and 37 by a sys- tem used elsewhere (28, 15). With “5” repre- senting the ideal for each practical property, like- 4The predominant grass species was little bluestem, Andropogon scoparius. Figure 20. Many sod clumps remain when fescuegrass sod is plowed and bedded. Some farmers do not like this soil condition for planting. but it contributes to water intake and reduces erosion. 21 ly ranges from the ideal are shown for each soil. For example, “workability” for soil unit 2 may vary from “6” to “9,” depending on the physical condition of the soil. A “6” rating means good but not ideal, or slightly too tight, but it is the best to be expected with soil unit 2. A “9” means very bad workability, the worst that is ever rec- ognized for this soil, or very much too heavy. The extreme rating of “10” is reserved for soils such as black alkali that cannot be worked satisfac- torily. These ratings show that natural erodibility is believed to be high for both 2 and 2X soils, but reaches the extreme only with 2X. Water and air properties are highly variable, depending on physical soil condition. Soil unit 2 includes more variability than 2X. Extremes of tightness and of air deficiency are seldom, if ever, found with 2X. Also, soil unit 2 at its best holds more’ able water than soil 2X. Available nutrientfl lems involve phosphorus and nitrogen. Withi phorus, the problem is strictly one of avail f’ rather than total. In the case of nitrogen. total and available are highly variable wit: tory and management. In comparing erodibility of soil unit 2X on small runoff-erosion plots, no diff“ can be shown clearly between the two site Table 4, higher soil loss per inch of runoff dicated for Austin clay (soil unit 2X) that Houston Black clay (soil unit 2), but whet influence of slope percent is taken into ac as shown by Figure 22, the two soils appear ilar in tendency to erode. At least, it is 0b that minor crop differences overshadow ences between the soils. 3.2 Q 3.0 2.8 Lu _. o: < 2.6 a n: / as / LL“ 2.4 m2 . / g m 2 2 Curve expressing /{D Pm ' data from several / ' o: other locations K= 2.o \‘/ o8 / §= ° / =23 1.8 u. ' Q / Oz / Q 1.6 Ir- / o; / O Eu 1.4 c D 4 m‘: / o “Jo 1.2 / e-z ‘f/ mo: / Q g8 1.0 I Q " x 4 0.8 \ 5 \Y - o 5141-4 tn o _ ' 0,6 1 (Exponent of slope percent " K as used by Zingg (33) >- 0.4 // and others (26) 0.2 // .8 l.O 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4;‘ X = PERCENT SLOPE Figure 21. Slope percent and average overall soil loss per inch of runoff on each oi 12 field-scale plots. O and P} all years that the plots were in row crops, corn or cotton, are shown in relation to empirical curve with exponent of" percent derived from data at several other locations (31. 24). ‘ 22 .2 .4 .6 Table 3. Average runoff. soil loss and oat yields from plot 3 19, on Houston Black clay. 2 percent slopes. 1945-49. ‘a while the plot was in continuous oats, compared \$.__q with losses from adjacent plot 212, in continuous _*——--___________ corn for the entire period. 1933-51 ” ' 1945-49 1 Five-year average annual results g Average annual soil loss 1h tons per acre Preceding slope soil loss cgglyliigld 0 Averaée annual Yum“ i" in°h°s Plot cropping history Crop Runoff per acre per acre x Average tons of soil loss per inch of runoff 193344 % Inches Tons Bushels 19 3-year rotation 2 Oats l.l 0.5 34.6 (oats) 22 Continuous corn 2 Corn 4.0 7.7 21.3 (corn) 1Average annual rainfall, 32.5 inches. The crops were not fertilized. . fily by the fact that the plots have been Worked i by hand for more than 20 years. The soil has not " o-________ ______-~—-'"" been compacted by tractors or other heavy tools. ~“°""_' Earthworms are more active than in most culti- '___“““"~* vated field soil. The absence of compaction evi- dently has favored earthworm populations and the earthworms have favored soil looseness and 40 so do v0 so 9o 10o 11o 12o 13o 14o 15k large Pore Spaces- m" “m” ' Fm Samples from the surface of the small plots I ure 22. Thirteen-year average (1931-43) runoff. soil show an average of 1.49 grams per cc for the bulk d soil loss per inch of runoff. shown in relation to d ' f _ ' 1 length on three plots of Austin clay. 4 percent slope. enslty O dry lumps Fle d Samples from the uous corn. Table 4. Summary of runoff and erosion from small plots in oil Samples for laboratory study were taken Zglveral different crop sequences at Temple. 1945- 52 from all small plots and all field-scale f-erosion plots. The following depths were 31/3 to 4% slope. Austin c_lay_soil s '1 s '11“ led: plow layer (0 to 6 or 8 inches); plow I-en th _ 1311s P2192: . . Crop or o Plot Rain- Run- per per inch I t0 lllClles; t0 IIIChGS; and t0 rotation rotation numbers fall off acre of runoff i . Measurements made on these soil samples YM" Incges Inches Tm“ '1'.°== , _ verage for the rotation led total organic matter and total nitrogen; (Cfgnfinufiusbcorn Contiguous 2 ads _1g.§ ' tt . a an . . . . .1116 retentlofl at pF'2'5 and p,F'4'2 and at cgugii. .31. m 2 5and7 32.3 2.5 8.4 3.4 olsture equivalent; .bulk density (paraffin Cousvgihofitgba 2 4am“ 323 l9 65 34 ' m . - . - _ ) and pore space (naphtha saturat1on) of Bermudagrass _ .11 lumps; Phosphorus extracted Wltl‘ CO2 e...$;::7%:::::i’...... °°"*".:="‘;;?.. .1‘. 1. 221% ‘ii ‘as’ nute bubbling of CO2 through soil 1n wa- Continuous cotron-rews _ 1 - . - on contour Continuous 13 32.3 2.8 9.5 3.4 water stability of 1 gram aggregates against Continuouslcotton. rows _ l4 32 3 4 3 u 8 2 7 Jklng and W?ter drops? dlsperslol? rat“) on Ceugglvllltfbz: Contiguous 11 szIs sI1 10I1 2Z1 11 that was first put through a 1/2-111011 mesh — — — — — — — — — — o — — — — — — — — ——_ — ' ; and water-stable aggregate on 2 and on _ 24 S1°P°'H°“s‘°"1 31”‘; :1" 5°“ m mesh screens, by the Yoder method (s2). 33333333; 33;; 22 3” 4- -° 1-9 P (Hubam green manure) 20 32.7 2.3 2.50 l.l e I e u e C ' Q hese various SO11 measurements indicate dif- C°“‘(‘§“j§§fn°§}f,f; manure) t‘ t . . . . es that help to explatnfunoff and eroslon cgfitifiiigg: 3:1: (Hubam) 11 32.7 1.2 0.31 0.3 _ . Physically, the soil 1n all small runoff- Continuous Bermudagrass l8 327 Us 009 02 n plots is looser and easier to Work than in (““g““°d) ' ' ' ' ‘areas is to be caused primar_ 1 Average annual rainfall was 32.5 inches. or 2 inches below the 39- year QVGICQO. 5.2. Summary of runoff and erosion on field-scale plots O and P. comparing losses with cotton and corn to those with ' Hubam clover. and oats with Hubam Number of R H s .1 1 plots Annual un° °1 °ss each crop‘ rainfall’ Corn Cotton Oats?» Hubam Corn Cotton Oats” Hubam - — — — — -—2— —- — Inghaes — — YS- — — — — — — E-II- — - —2'£ons per acaeg- — — — — — 2 36.4 . . . — . . . — 2 25.1 0.5 0.4 0.5 — 0.5 1.1 0.1 — 2 49.4 4.4 4.3 3.2 — 8.2 14.5 1.5 — 4 38.1 3.4 — 3.1 4 1 3.8 — 1.0 2.8 4 44.5 3.0 — 0.9 3.0 2.2 — 0.2 1.5 4 27.4 1.5 — 1.8 1.0 1.5 — 0.6 0.6 4 19.6 0.3 — 0.8 0.4 1.3 — 1.0 0.4 6 32.7 — — — t1ba Z1 an nncnzs l. Q F f- Q CD m // 1 SOIL LOSS - tons PER ACRE Figure 33. Ten years of runoff and erosion on field- scale plot. P-5. shown in relation to rainfall and crop. Soil. Houston Black clay. 60 percent; Austin clay, 4O percent. Slope. 3.0 percent. SCS Capability Unit, 111-2 and 2X. ANNUAL RAINFALL IN INCHES I I I 36.11 25.1 '09.! 38.1 N.5 27.11 19.6 32.7 2H0 27.1 31,1 ,9 1 1 1 1 I I chor eaodu I I I Oats Corn Cotton Corn Nu an Oat Corn Oats- Cotton Oats- Fescue- Fescue- 20 TONSI Clover Clover Clover Clover 6 I2 INCNES f? Z% }f I Z Z o ‘H “Y! w 3 SOIL LOSS - TONS PER ACRE nuuorr - f}f} 0t LOSS — u } t1\ x A ?}) % \ \ \ ,1“ / m O P ~ s YEAR Figure 34. Ten years of runoff and erosion on field- scale plot. P-6. shown in relation to rainfall and crop. Soil. Houston Black clay, 90 percent; Austin clay. 1O percent. Slope, 3.0 percent. SCS Capability Unit, 111-2 and 2X. Figure 35. Earthworms have a great influence on physi- cal properties of Blackland soils. Their effect is most evi- dent in permanent grass or where the soil is mulched. Ex- cessive cropping and heavy machinery on wet soil reduce earthworms to a minimum and cause dense soil. 26 Table 6. Organic matter and nitrogen in desurfa after 2O years of grass compared with of cultivation ’ Native grass Continuous culti I‘ Inches Organic matter Nitrogen Organic matter ‘~ — — — — — — — Percent — — — - o to 11/, 2.4 0.1a 1.1 11/2 to a 1.9 0.0a 1.1 a 1° s 1.4 0.07 1.1 s to 12 1.3 0.01 1.2 same soil types collected nearby, for comp‘ showed average bulk density of 1.77 gra ' cc. Highest bulk density measured in the s, soil of the small plots was 1.59. In field ar is common to find bulk densities of dry lu l; high as 1.9 to 2.1 grams per cc. The highe sities are indications of the condition know - “plowpan,” which is considered serious in land soils (13). No dense soil or distinct i’ ing, as With plowpans, has been observed” small plots. Figure 38 shows a typical co, between surface soil from the small plots 1; from a nearby field area on the station. Th, sample represents only a slight compaction (dry-bulk density, 1.77) but it lacks the I aggregate porosity and the worm holes o’ small plot sample. ‘ I Some differences in soil organic matter lation to cropping history have been noted. _ have been no consistent differences betwee, Houston Black clay and the Austin clay ~ even though the Houston Black clay appears , er. Organic matter differences noted were; in continuous corn, plow layer—2.05 perce plots in crop rotations, plow layer-2.28 pef continuous Bermudagrass for 20 years, 0 to ches—3.94 percent, and 3 to 6 inches—3.2. cent. These differences in organic matter; have had some effect on runoff and erosion. ' ever, the cropping differences associated wit jor organic matter variables prevent any of the effect of the organic matter, as suc , Slaking and water-drop testing showi lumps of soil of 1 gram weight (IA; to 1/2 in Table 7. Aggregate stability of Austin clay soil cated by the number of falling drops re destroy individual 1-gram lumps ‘T Plot number Land use 1 Continuous corn Rotation (mostly corn) Continuous corn Rotations Rotations Bermudagrass Rotation Rotation Rotation Rotation Rotation (desurfaced plot) Rotation (desurfaced plot) Rotation Rotation (mostly cotton) Rotation (mostly cotton) Rotation Rotation Desurfaced. rotation Desurfaced. native grass for 2O years hihdl—lhih#l—lhiifl UIUTkOONEI—I¢CD@QUDUTIPOOB) 1 Each value is an average of 5 or more replications. The‘ was 6O cm. " biz/axon or__scs son. uu1r_2 lHOUSTO§_BLACK CLAY) mm 4 (BQTTQHLAND), \ DEEP, new! rzxrunzo, SLOWLY PERMEABLE sons. too little too much or or too 10w I too tight or D or too loose E too high or A or too fine L too coarse O l 2 3 4 5 6 '7 8 9 l0 a‘ gt: jProper Seedbed) lbltachability) ' ‘Crust .5 at the Surface through Ploupan I‘ _ through Subsoil (‘Jleld In Plow Layer l lleld per‘ m». of subsoil f it!‘ l: Held (Limits rate of release) f lied for pl-l-V "i" l) Pollen: -—"' I Iltrogen ‘lo filtrates 4 . v (he lphorus -—-* 5 “b1! Phosphorus ' _ aural mg: whlchlmay occur in space and time. l“ e 36. Characterization oi SCS Soil Unit 2 (Houston - ) and 4 (bottomland). deep, heavy textured, slowly le soils. ) are more stable in grass plots than un- ltivation (Table 7). surfaced plots show slightly more aggre- tability than most normal soil plots. This fistent with the fact that in the past desur- §plot 11 lost less soil per inch of runoff than ith normal soil. Its aggregation helps to erosion. e grass effect on Houston Black clay is t but is smaller than for the Austin. i» me rotation plots show a little more aggre- tability than plots in continuous cropping be difference is small. Of course, most of tations had a row crop more than 50 per- the time, so big effects on physical prop- or organic matter would not be expected. ispersion ratios and wet-sieving aggregate es show smaller differences between grass Aggregate stability of Houston Black clay soil in runoff plots as indicated by the number of falling drops required to destroy individual 1-gram lumps er Land use Drops1 Rotation Bermudagrass Rotation Rotation Rotation Continuous corn n-I QQCJUIODQQI “flue is an average of 5 or more replications. The drop fall CHARACTERIZATION OF‘ SCS SOIL UNIT 2X (AUSTIN CLAY), DEEP, HEAVY TEXTURED, MODERATELY PERMEABLE SOIL. too little too much or or too low 1 too tight O!‘ D Ol‘ too loose E too high or A or too fine 1, too coarse O 1 2 3 4 5 6 7 8 9 1O Depth for Roots workability (Proper Seedbed) Erodibillty (Detachibilityl Tendency to Crust Water Intake at the Surface water Movement through Plowpan Water Movement through Subsoil Useful Water Held in Plow Layer Useful Water Held per foot of Subsoil ‘lightness Hater is Held (Limits rate of release) Aeration Acid-Base (pH) i’ Lime or S needed for pH-'7 ~—> Salts-Plant Poisons Plant Food Total Nitrogen Available Nitrates Total Phosphorus -i~ Avail able Phosphorus Potash -—- Other- general ~7- The range which may occur in space and time. Figure 37. Characterization of SCS Soil Unit 2X (Austin clay). deep, heavy textured. moderately permeable soil. plots and cultivated plots than the slaking and water-drop test. However, results with all tests tend to point in the same direction. Long per- iods of grass definitely favor water-stable soil units or aggregates. The effect of short rotations on soil aggregates has been very small, as gauged by the methods of measurements used. If the difference between pF-2.5 and 4.2 in the laboratory (air-pressure extraction) is taken as an index of available moisture, some small dif- ferences among plots are shown on the two small plot layouts (Table 9). These data show a 2 to 3 percent difference of available water capacity in favor of Houston Black clay. (Other data on the station show as much as 5 percent available moisture capacity in favor of Houston Black clay.) On Austin clay, Table 9. Total available water-holding capacity from pF 2.5 to 4.2. determined in the laboratory for runoff- erosion plots of Houston Black clay and Austin clay Plow layer Available moisture percent (Laboratory methods) Continuous Rotation Grass row crops ots plots Austin clay ll.l 12.1 12.3 (2 plots) (13 plots) (1 plot) 9.5 11.5 (3 desurtaced (l desurfaced plots) plot. 2O yrs. grass) Houston Black clay 14.1 14.1 12.5 27 0327/ Figure 38. Typical, loose, porous Austin clay soil in small plots where no heavy machinery has been used (ri pared with normally dense Austin clay in a field area (left). Vigorous earthworm activity has helped keep the soil- -- in the small plots. Heavy machinery compacts the field soil. the surface layer of desurfaced plots shows slight- improving sweetclovers. There is a sugj ly less available moisture capacity than normal 0f an increase in phosphorus extracted Wi soil. There is a small difference favoring rota- bon dioxide All rotation plots which We; tion plots and grass plots on Austin clay but not , , ' ’ § on Houston Black clay. This is consistent with tlhzed’ gave an average Op 5-8 ppm of l, the known tendency of Austin clay to respond to 00111113100 Wlth 3-4 £01‘ 00111311100118 00111 P10 f physical improvement better than Houston Black no fertilizer. The Bermudagrass plot on clay. The main reason probably is the heavier clay (p101; 6) Showed 2037 ppm Of p205, a’ texture of Houston Black clay, which is likely to grass plot on Houston Black clay 69 ppm. predommate Over other factors' phorus tests are interpreted as indicatinga Fertilization with phosphorus has been prac- fer repeated applications ef mederete 81111011 ticed during recent yearsifor the growth of soil- phosphorus fertilizer if serious nutrient has been repeatedly compacted with machinery. 28 pure 40. Deep dark porous grass-root filled soil pro- Austin clay in native prairie grass pasture on the and station. This soil has never been plowed. The j e contains 5.5 percent organic matter. 1' are to be avoided. This also is the general lusion from fertilizer experiments? ‘on to Mechanical Factors ‘Contour bedding always has showed a sav- f Water and soil in small plots over flat plant- gThe amount of the saving depends on the of the beds, or ridges, and the type of rain- Past records (18) show reductions of 50 nt or more in the losses of both soil and wa- L111: is recognized that field bedding often can- p as perfectly contoured as in the small plots, hat the field control is, therefore, less. lFrom 1945 through 1949, contour-planted cot- §(pl0t 13) was compared with cotton planted l, d down the slope (plot 14). No beds were after 1946. All working was by hand. In o case, contouring apparently reduced water ffrom 4.3 inches (plot 14) to 2.8 inches and i ed soil loss from 11.8 to 9.5 tons (Table 4). eye-saving is enough to be important. Also, the ‘blished data of the Blacklan.d station, by J. W. Col- ; E. D.~Cook and R. P. Bates. a. mixlutxixzttll‘ l‘ " ‘* ‘l 1"?‘ Nf-v eicm m i»: - Figure 41. Austin clay soil under cultivation for 60 years, with serious erosion, on a 3 percent slope. The sur- face soil contains 1.9 percent organic matter. This site would be like Figure 40. which is 30 feet away. except for cropping and erosion. contoured cotton gave a yield of 253 pounds of lint per acre as compared with 207 pounds for rows down the slope. On field-scale plots O and P, as shown in Table 10, contour bedding resulted in lower water and soil losses than flat handling of the soil, even though the crop residue was removed from four of the bedded plots. The saving evident from bedding was 0.4 inch of water and 1.1 tons of soil per acre per year during 1949-51. These were Table 10. Summary of results on field-scale plots O and P. with three methods of tillage and artificial residue management. in a Z-year rotation of cotton. oats with clover, 1949-51 Rain- Run- Soil loss Method Management Plots fall off per acre Inches Inches Tons 11 Residue on top. Flat. No bedding. 4 27.20 1.3 2.8 2 Residue turned under. - Bedded. Standard practice. 4 27.20 1.0 1.6 32 Residue (oats-clover) removed. Bedded. 4 27.20 0.9 1.7 1 In 1949. the residue was removed for plowing and was then returned to the surface. In 1950 and 1951. the land was prepared by sub- tillage with a Graham-Hoeme plow. ‘~’ In method 3, the oats with clover was baled and removed. Other- wise the method was the same as method 2. 29 640 L-2 /_\ \ /\ 5 \// \ E \ _ 1.54 cs4 p 632 2s so vs _ _ _ 100' 12s. 15o 1'15 NORIZOITAL DISTANCE - FEET Figure 42. Cross section oi terraces L-Z. L-3 and L-4. I951. aiter 6 years oi maintenance by plowing. The de- pression midway between L-2 and L-3 is the dead iurrow leit by ordinary plowing. The interval between L-3 and L-4 shows no such depression because all oi the furrow slices irom the channel oi L-4lto the ridge oi L-3 have been turned uphill. Terrace ridge L-2 is somewhat low (10 inches). whereas L-3 and L-4 are a good I6 inches high. An extra backiurrow on L-2 with dead iurrow in the channel would increase the height to a saie 15 to I8 inches. This practice has been followed on L-3. lOW rainfall years. Residue handling was artific- ial in 1949 and probably not as effective as with good subsurface plowing. Studies continued since 1945 showed that good terrace maintenance on standard Nichols (drainage) type terraces (16) is obtained by the following practices: plowing so a backfurrow falls on the terraceridge; leaving a dead furrow in the terrace channel; and turning all furrow slices uphill in the interval between terraces. Terrace maintenance without plowing the land uphill between terraces has tended to leave an undesirable low place midway between terraces. This may be avoided in part by shifting the po- sition of the dead furrows in the channel and be- tween terraces year after year. Some care and skill by the operator are required to obtain a de- sirable cross section by this method. Uphill plow- ing is simpler and better, but reversible disk plows Figure 43. Newly planted cotton in strips alternating with Mustang oats and Hubam. Erosion control and pro are good on I to 3 percent slopes (Class II land). But on slopes oi 3 to 4 percent (Class III, Austin clay). rills and f gullies have formed. . 30 are not now available for uphill plowing. y, a low area is developed. between terraces, of the land slope is increased. This caus creased soil movement and exposure of subs well as inconvenience in land preparation‘ management. A Even with a desirable terrace cross se Figure 43, there is an increase in slope pet from the top of one terrace ridge to the bot . the channel of the terrace below. In this fi the original land slope was 3.8 percent. I well-maintained terraces it now averages 7.3 cent from ridgetop to channel bottom of the. lower terrace. Uphill plowing counteracts.‘ tendency for this increased percent of s10‘ cause greater erosion. j Re-plowing a second backfurrow on th race ridge with dead furrow in the channel, i; the first plowing, was tested as a means of a taining adequate terrace height. This was I factory but generally not necessary. Settl race heights of 15 to 18 inches have been tained in most cases by a single backfurro the ridge. Three years of stripcropping results We ported previously on the field-scale plots P (18). It is now possible to add 3 more making a total of 6 years of records, summa‘ in Table 11. Details by plots and slopes are y, in Figures 23 through 34. Stripcropping s, considerable reduction of soil loss, especiallf the 3 percent slope. Water loss differences Table ll. Average annual soil and water losses contoured rotation and a similar rotation cropped. 6 plots each. 1939-44 Average Average annual - Plots slope Cropping Treatment rainiall Runoii ' Percent Inches Inches O 2 3-year rotation, Contoured 36.14 1.76 cotton, oats. corn 2 Stripcropped 36.14 1.67 3 " Contoured 36.14 3.14 3 Stripcropped 36.14 2.55 rorog itthe stripcropped plots. The difference is n the 2 percent slope. ' fs discussed in previous publications (18, "ll and gully erosion were not stopped by i‘ opping on the 3 percent slope. A big ad- fe of well-maintained terraces over strip- 'ng is the prevention and control of gullies. tier, when terraces are not supported by y maintenance and by good cropping prac- p, hey often break during critical periods of p rainfall and intensify gully formation. é this standpoint, stripcropping introduces Hazards. stripcropping is being used successfully on area on the station, with a 2-year rotation ton, oats with Hubam. During the past few } of comparatively low rainfall, some rill eros- yd small gullies have formed where the slopes tween 3 and 4 percent. On slopes of 2 to 3 nt, erosion does not appear serious. The i; are approximately 90 feet wide. Uneven j: is taken up by the strip of oats with clover. opography is comparatively uniform, which ssary for satisfactory stripcropping. Preparation and Management cubsoiling was tested at several locations and ~ were discussed in a previous publication The only effect noted on water intake was rary and was not considered worthwhile. ifrecently, chiseling to about 1O or 12 inches een practiced with chisels mounted on a ster-type of trash-mulch tool carrier. The _ purpose of this work has been to break up ‘il in dry weather so it can be plowed with Qrface sweeps. The chisels can be pulled in jgure 44. Subsurface or trash-mulch plowing is a ting new practice for economy. efficiency and conser- i’ in the Blackland. Figure 45. Subsurface plows (used to the north and west) are readily adapted to Blackland conditions. When the ground is very dry. it is necessary to break the soil with chisels before plowing. Deep-furrow or hard-ground drilling of small grain and fertilizer is another promising trash-mulch practice. This same carrier can be used with the deep-furrow drill. soil that is essentially air dry and is difficult to plow. Subsurface (or “plowpan”) shattering when the soil is quite dry is more likely to be beneficial than when the soil is moist. Even so, the only effects observed from chiseling have been temporary. This soil slakes thoroughly in water, either in the laboratory or in the field, and there seems to be good reason to conclude that most of Figure 46. Deep-furrow, hard-ground drill that is doing a good job of putting small grain and fertilizer 3 to 4 inches deep into hard, dry ground. This drill, with shoe-type openers and spring shanks. is useful for drilling into biennial clover. established grass, lanes or heavy residues of any kind. 31 the influence of chiseling is lost with the first soaking rains. The properties of shrinkage and swelling are developed to a high degree in the Blackland clay soils (21). Volume changes of more than 25 per- cent have been measured with standard 3-inch cores in drying from saturation to complete dry- ness. It seems inevitable that such volume changes will repeatedly break dense soil layers of the upper profile into blocks, in much the same manner as a chisel. In the laboratory, the soil volume begins to reduce almost immediately as water is lost from a saturated core or lump, and in the field visible shrinkage cracks appear when the soil is still well above the wilting range of moisture content. Subsurface plowing, or trash-mulch tillage, has not given conclusive evidence regarding its value in the Blackland. However, considerable experience has been obtained with tools and meth- ods similar to those used in the Amarillo area (20) and elsewhere. These tools can be used in the Blackland Prairie. Residues left at the sur- face appear to give significant soil protection and maximum opportunity for infiltration (6, 12, 18). The soil layer that is lifted and shattered by sub- surface sweeps is loose and in an excellent con- dition to receive water. In addition to possible soil and water conservation benefits, there may be practical advantages that favor certain trash- mulch methods, strictly from the standpoint of economical production. Subsurface plowing has been satisfactory after all of the major crops, i.e., cotton, corn, small grain, sorghum grain, sor- ghum hay (redtop cane), sweetclover and fescue- grass sod. Deep-furrow drilling of small grain and fertilizer into hard ground with shoe-type openers on spring shanks also has been success- ful. The drill can be mounted on the same carrier used for subsurface plowing, chiseling or field cultivating. Trash-mulch is“ now being compared t, plowing on gauged terraces, to determine i fects on runoff. And on large, field-scale; O and P, trash-mulch plowing is used on all in connection with studies of the amount, t bution and influences of different types of? dues in three cropping systems. On these plots, and on other plots studied, the subsu plow has extra advantages. It represents a venient method for avoiding high and low within plots. With other plowing, the dead; rows and backfurrows create these difficult Major uncertainties about trash-mulch ing involve questions of J ohnsongrass contr the economy of bedding before planting row i It appears that Johnsongrass can be cont satisfactorily, especially when land is su a plowed early before severe summer dry pet The necessity of bedding for row crops re uncertain. If necessary, land that has been surface plowed can be bedded as well as any i, plowed ground, but this is more expensive» bedding without plowing. Preliminary tes planting without bedding have been satisfa j, Trash-mulch plowing without bedding is the method being studied that may prove to bej cheaper and better for conservation and pr tion than the farm practice of bedding an bedding for row crop production. 7' Crop Production Cotton Yields and Root Rot Highest yields of cotton on the statio , being obtained in rotations where cotton f0 small grain or fescuegrass with Hubam or v These rotations are partly an outgrowth of i runoff-erosion studies which showed the e, tiveness of small grain and grass for conserv of water and soil. Recent plot rotation data , averageyield increases of 100 to 150 poun; Figure 47. Blackland clay soil breaks into large clods like this when turned with a disk plow while the soil is ve The clods are too coarse for dry planting oi small grain. They slake readily when rains come and tend to form a l crust that is only slowly permeable to water. Subsurface plowing shatters the soil into smaller lumps and leaves in the surface. 32 i figure 48. Crop rotation plots with cotton following various close-growing or soil-improving crops. One of the best is for yield, root-rot reduction. and conservation is cotton following Mustang oats with Hubam sweetclover. Minimum f- has been obtained where cotton follows fescuegrass alone or with annual legumes. Icotton per acre for the rotations over con- us cotton (17). There has been some tend- l. for a reduction in cotton root rot where the in follows 1 year of small grain with Hubam l: ch, or 2 years of fescuegrass, alone or with or vetch. iflCotton yield apparently has been increased »_- soil-conserving practice of contouring. Con- t yield increases of as much as 200 pounds d cotton per acre have resulted from spac- ltton plants at 2 to 4 inches in 40-inch rows spacings of 8 to 12 inches. Yield, conserva- inland mechanical harvesting are favored by simple, inexpensive practice. Direct fertilization of cotton on the station ‘hown little or no effect in standard rotations e 40 pounds of P205 per acre are used with mall grain and clover preceding the cotton. f-station work, on land that has been crop- iontinuously without fertilizer, a response een obtained to combined treatments of ni- and phosphorus (11). g Yields in small runoff-erosion plots, comparatively I yield levels of 23 bushels per acre were ob- if during 20 years of continuous cropping to with no fertilizer. The organic matter con- f the surface and subsurface soil at the end e 20-year period was 2.0 percent. Results "about the same on one plot of Houston Black and one plot of Austin clay. In field plots, ierage corn yield of 29 bushels per acre was J ed on Houston Black clay during a differ- g-year period. Final soil organic matter per- ‘ges were 2.5 in the surface and 2.3 in the rface. No distinct yield trends with time jevident in any of these tests of continuous (29). Higher corn yields are obtained by improved ids, closer plant spacing, crop rotation with corn following phosphated sweetclover (either alone or with small grain or grass), limiting corn production to Well-adapted land and phosphate and nitrogen fertilizer, if needed. During the past 6 years of subnormal rain- fall, average corn yields on the station have been near 45 bushels per acre. On level Houston Black clay, the yields have been near 55 bushels. Com- parisons indicate that Houston Black clay yields about 5 to 8 bushels per acre more than Austin clay with similar management (9). Moisture studies show that Houston Black clay on the sta- tion holds from 2 to 5 percent more available wa- ter than Austin clay. An average difference (3.5 percent) means that Houston Black clay can store about 0.5 inch of water per foot more than Aus- tin clay. Grain Sorghum Yields The production pattern with grain sorghum is similar to that for corn. If anything, the grain sorghum yield has been less responsive to increase than corn. This is probably because grain sor- ghum is grown more often on sloping or depleted land than is corn. Crops following grain sor- ghum may tend to need nitrogen fertilizer more than after corn, and certainly more than after cotton. Close stands, vigorous growth and heavy residues, characteristics that go with high yields per acre, also are the characteristics for the best prevention of runoff, erosion and soil depletion. Small Grain with Sweetclover Fall-seeded oats, barley and wheat, with phos- phate fertilizer and sweetclover, have become the backbone of station conservation and production. The largest acreage is oats, with barley next and wheat grown only to a limited extent. These are multiple-purpose crops. In cool weather small grain constitutes the main grazing. By early March, it is necessary to remove cattle from areas 33 Where maximum grain production or a heavy hay yield is expected. Some fields are grazed out com- pletely to provide an abundance of pasture dur- ing March, April and May. Small grain yields have been increased con- sistently by improved varieties, phosphate fertili- zation and deep drilling. Oats, in particular, seems to profit from deep drilling which prevents germination from early fall showers before the ground has enough deep moisture to permit con- tinuous growth. Nitrogen fertilizer helps to give quicker ground cover and more winter grazing. On the station, nitrogen is used sparingly because of dependence on sweetclover, and the fact that heavy winter growth by small grain tends to darn- age sweetclover stands and growth. In dry periods, small grain profits from level, moist soil, i.e., Class I land, Houston Black clay or bottomland. But on the average, small grain yields are less sensitive to soil and slope than row crops. Average yields of leading varieties in va- riety trials during the past 4 years (10) have been: Mustang oats, 62 bushels; Quanah wheat, 21 bushels; and Cordova barley, 38 bushels. These trials have been on Class I or Class II land, Hous- ton Black clay. Field yields have averaged about 2O percent less than the variety trials. A part of the difference is loss during harvest, which at present seems unavoidable, either with direct combining or by windrowing followed by pickup with a combine. Grazing returns from small grain and sweet- clover reached highs of 342 pounds of steer gain per acre in 1946-47 and 339 pounds in 1952. The average for oats in 1952 was 275 pounds. The lowest, on Austin clay, Classes III and IV 198 pounds. clover in 1952 gave 260 pounds of steer ga' acre, or essentially the same as oats. Wh never grazed completely because of the smallji age. Winter grazing on small grain reac high of 17 8 pounds of steer gain per acre o‘ with clover before March 1, 1946. The avf for several years, without nitrogen fertili about 60 pounds per acre. Steer gain pe from all fields of biennial sweetclover on t barley stubble ranged from 2O to 65 pou l 1952, and from 31 to 60 pounds in 1953. i These returns per acre give a good indi of the value of crops that provide excellep protection and water conservation during th" ical spring period of highest rainfall. At n‘ prices for beef and other animal products/t turn per acre appears generally competitive? the net return from cash crops. On Class I11 Class IV land, Austin clay, Houston Black and Houston clay (not represented on th tion), the soil-conserving combinations of i‘ grain with sweetclover are in an especially f, able economic position in comparison with? crops. 1 Other Grazing Crops and Beef Production Proper land use as now practiced has l the use of a strip of bottomland along Boggy for permanent pasture. l cultivated crops. It is mostly Class V (wet l The main perennial grasses are Bermudagr the lowest parts and buffalograss on higher areas. Cool season grasses, Texas Winter Figure 49. In extreme cases. phosphate fertilizer makes the difference between conservation and production, or l‘ Winter-killing of oats was severe on this depleted Austin clay soil where no phosphate was used. Sweetclover an other crops tend to need moderate fertilization with phosphate on lime-rich Blackland soils. 34 Complete grazing of barle Overflow and local spots prevent the successful use of this Ian 3. igure 5U. Dense soil cover oi fall-drilled oats with sweetclover being grazed with choice steer calves in conservation g system on Class III land. Oats and clover are the backbone oi year-round grazing and conservation in the Blackland. ‘pa leucotricha) , rescuegrass (Bromus cathar- ) and little wild barley (H ordeum pussillum) , " contribute to the total growth and the length ge grazing season. During 6 years 0f record this pasture has given profitable returns of fpounds of steer gain per acre at an average 30f gain of 1.0 pound per head per day. Rapid , of gain are obtained from early growth in ih and April. During midsummer, when gains lower than 1.0 pound per head per day, it is ly better to depend on supplemental grazing. I%As shown by small plots, soil erosion is in- ficant with good grass cover. Water intake fnds greatly on grazing intensity, especially g g Wet periods. With good grazing manage- ", shrinkage, earthworms and roots keep the are soil open and receptive to water. On the .1 ge, there is more runoff from grazed graves re than from small runoff plots. Careful ng management is the key to high water in- jyand to high returns per acre, year after year. e grazed conservatively, permanent grasses “A survived and produced well during recent mely dry years. he station maintains one 8-acre native grass re, consisting of little bluestem (Andropogon 'rius), big bluestem (A. furcatus), Indian- , (Sorghastrum nutans), side-oats grama lteloua curtipendula) , Texas wintergrass l leucotricha), wild alfalfa (Psoralea tenui- ), catclaw sensitive brier (Mimosa biunci- i, yellow neptuni ( N eptunia Zutea) and many minor species. The 5-year average return 1' re, 1947-51, was 90 pounds of steer gain at te of 1.6 pounds per head per day. Recent- is pasture has been grazed in accordance its growth by species, as recommended by O (1) rather than on an arbitrary schedule. flyears by this method gave 142 pounds of A gain per acre in 1952 at 2.3 pounds per head per day, and 152 pounds in 1953 at 2.5 pounds per head per day. Johnsongrass with sweetclover or Johnson- grass with small grain and sweetclover is a val- uable conservation grazing crop. Its full poten- tialities have not been realized because of the damage by J ohnsongrass as a weed in row-crop farming. Also, Johnsongrass often dies under normal grazing. Two years of results on eroded, sloping land (Classes II and III, Austin clay) gave an average return of 160 pounds of steer gain per acre at a rate of 1.4 pounds per head per day from oats and Hubam drilled into J ohn- songrass. Use of Johnsongrass with sweetclover, or with other species, probably is more attractive on land that is too sloping for much cotton or corn (Classes III and IV). In rotations with grain sorghum for farm use as feed, there appears to be little need to control J ohnsongrass completely if the land can be used for grazing combinations during 1 or more years before each crop of grain sorghum. A rotation of this type used success- fully on the station on Class II and Class III land, Houston Black clay and Austin clay, consists of" 1 year of grain sorghum followed by 2 years of barley and sweetclover with the J ohnsongrass. This is a cheap and profitable rotation when graz- ing and grain are balanced with the livestock load on the farm. Sudangrass, sweet or common, is one of our best summer grazing crops for year-round graz- ing systems. The 6-year average acre return has been 309 pounds of steer gain at an average rate of 1.9 pounds per head per day. This grazing is especially valuable because it comes in hot, dry weather when other grazing is scarce. A No runoff and erosion measurements are available for Sudangrass planted in 40-inch rows. 35 returns of more than 200 pounds oi steer gain per acre. Where contour planted and not overgrazed, it gives better control than corn or cotton. Trash- mulch methods, minimum land preparation and minimum cultivation may give better conserva- tion with Sudangrass. However, at present this crop is grown like other row crops, in 2 or 3-year rotations following 1 or 2 years of soil-conserving small grain with clover. Other grasses for conservation and produc- tion have been studied and tested, both in small plots and in field areas. Fescuegrass (Ky. 31 or Alta) is being used to some extent for cool-season grazing or hay. It can be established consistently from fall or winter drilling. Yields are low but, in combinations with sweetclovers or alfalfa, the total legume and grass yield may be satisfactory. The root growth of fescuegrass has a strong con- Figure 52. Feedlot finishing for maximum profit is an essential part of a well-balanced conservation beei-produ plan. Plenty of hay and grain for cattle finishing and wintering can be produced on typical Blackland. 36 \ Figure 51. Sudangrass for summer supplementary grazing is an important part of year-round grazing in conse farming systems. Sudangrass is grown in rotation with small grain and sweetclover on Class II and Class III landp. ditioning effect on the soil. It may find a W use with legumes, especially on moist sites. I KR bluestem (Andropogon ischaevnum v is a warm-season grass that can be establi successfully by drilling in rows in the spring; persists and thickens under varied conditions 7 management. Highest grazing returns have g obtained when cool-season clovers are grown KR bluestem for early grazing. Its use is re mended in combination with clovers on shalt severely-eroded or steeply-sloping soils. I w»- * g Buffelgrass (Pennisetum ciliare), Cauca bluestem (Andropogon caucasicus) and blue r icum (Panicum antidotale) are three of the p, promising introduced grasses now being tes However, the only good stands obtained have .... .. “A Hm M . A. _ . b ,plots, and hay yields have not been equal ngrass. There is no assurance that these fintroduced grasses, except Bermudagrass, 7 find a prominent place in Blackland ag- V Consistent and quick establishment, ity t0 compete with Johnsongrass are Ystics needed but still are not entirely r by any of the numerous Warm-season ‘that have been tested at this station. ; various intermediate or tall native gras- is area are too slow in establishment for fort-time crop rotations. For permanent eture or grass hay (other than low-lying ‘ftable for Bermudagrass), Johnsongrass ‘firiative grasses probably are the best spe- _Wn. It takes several years to get Well- ed stands of the tall native grasses. Then essary to follow proper tall grass grazing management (1). The most satisfactory native grasses to establish include: Indiangrass (Sor- ghastrum nataus), little blustem (Andropogon scoparius), big bluestem (A. furcatus), side-oats grama (Bouteloua curtipenduia) and switchgrass (Panicum virgatum). For close grazing on dry sites, the best na- tive grass that can be seeded successfully is buffalograss (Buchloe dactyloides). There is hope of finding other grasses that will improve conservation and production in the Blackland, but more attention is being given to improved management and treatment of the gras- ses that We now have and Whose good and bad characters are known. Johnsongrass, Bermuda- grass and tall native grasses are the most prom- ising for grassland improvement through improv- ed management. 37 (1) (2) (3) (4) (5) BIBLIOGRAPHY Allred, B. W. 1950. Practical Grassland Management. Sheep and Goat Raiser Magazine Press. San Angelo, Texas. Baird, Ralph W. 1950. Rates and Amounts of Runoff for the Blacklands of Texas. USDA Technical Bulletin N0. 1022. Baver, L. D. 1940. Soil Physics. New York. Blaney, Harry F., and Morin, Karl V. 1942. Evaporation and Consumptive Use of Wa- ter Formulas. Trans. Am. Geophys. Union, part 1:76-83. Blaney, Harry F., and Criddle, Wayne D. 1950. Determining Water Requirements in Irri- gated Areas from Climatological and Irrigation Data. USDA SCS-TP-96. John Wiley and Sons, Inc., (6) Borst, Harold L., McCall, A. G., and Bell, F. G. 1945. Investigations in Erosion Control and the Reclamation of Eroded Land at the Northwest Appalachian Conservation Experiment Station, Zanesville, Ohio, 1934-42.USDA Technical Bulletin No. 888. (7) Browning, G. M. 1939. Comparison of The Dry Combustion and Rapid Titration Methods for Determin- ing Organic Matter in Soil. Soil Sci. Soc. Amer. Proc. (1938) 3:158-161. (8) Carter, W. T. 1931. The Soils of Texas. TAES Bulletin 431. (9) Collier, J. W. 1951. Corn Fertility Studied at the Blackland Station, 1949-1951. TAES Progress Report 1418. (10) Collier, J. W., and Atkins, I. M. 1952. Small Grain Variety Tests at the Blackland Experiment Station, 1949-52. TAES Progress Report 1503. (11) Cook, E. D., Smith, R. M., and Thompson, D. O. 1953. Cotton Report for the Blackland Experi- ment Station, 1952. TAES Progress Report 1553. (12) Duley, F. L., and Kelley, L. L. 1941. Surface Condition of Soil and Time of Ap- plication as Related to Intake of Wa- ter. USDA Circular No. 608. (13) Elder, W. R. 1951. Factors Affecting Rate of Water Intake in Texas Blacklands. Jour. of Soil and Water Conservation 6:195-197, 199. (14) Ensminger, L, E., and Larson, H. W. E. 1944. Carbonic Acid Soluble Phosphorus and Lime Content of Idaho Soils in Rela- tion to Crop Response to Phosphate Fertilization. Soil Sci. 58:253-258. (15) Fuhriman, D. K., and Smith, R. M. 1951. Conservation and Consumptive Use of Wa- ter with Sugar Cane Under Irrigation in the Soil Coastal Area of Puerto Rico. The J our. of Agr., University of Puerto Rico, Rio Piedras. (16) Henry, Jerome J. 1937. The Nichols Terrace: An Improved Chan- nel-Type Terrace for the Southeast. XXX \ USDA Farmers Bulletin 1790. Q17) Heré/iéyfiz. J., and Cook, E. n. 1953. Crop Rotation and Cotton Root-Rot Con- trol Studies at the Blackland Experi- ment Station, 1948-52. TAES Progress Report 1588. (13) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) <30) (31) (32) (33) i‘ Hill, H. 0., Peevy, W. J., McCall, A. s., an Bell, F. G. 3 1944. Investigations in Erosion Control :1 lamation of Eroded Land at th land Conservation Experiment j Temple, Texas, 1931-41. USD nical Bulletin 859. (Cooperati Texas Agr. Exp. Station.) l Hill H. O. 1946. Erosion with Strip Cropping and) ing in the Texas Blacklands. ~ SCS-Tp-72. Johnson, Wendell C. 1950. Stubble-Mulch Farming on Whea the Southern High Plains. US cular No. 860. { Johnston, J. R., and Hill, H. O. 1944. A Study of the Shrinkage and- ‘ Properties of Rendzina Soils. Soc. Amer. Proc. 9:24-29. l" Marshall, R. M. l 1 Soil Conse, 1950. Land Capacity Guide. Service, Fort Worth, Texas ( \ service use only). f, i,‘ Miller, M. F. { 1936. Cropping Systems in Relationto i? 1 Control. Missouri Agr. Exp. Bulletin 366. Musgrave, G. W. _ 1953. Estimating Evapotranspiration. l: servation Service. In process j lication. 7 Peech, Michael, and English, Leah. 1944. Rapid Microchemical Soil Tests. 57:167-195. Smith, D. D., and Whitt, D. M. 7i 1947. Estimating Soil Losses from Field of Claypan Soil. Soil Sci. ‘I Amer. 12:485-490. f Smith, R. M., and Cernuda, C. F. . 1951. Some Applications of Water-Drop. ity Testing to Tropical Soils of‘. iRlligo. Soil Sci. No. 5, Volume Smith, R. M., and Samuels, George 1 1950. A System of Soil Profile Characte ~ Jour. of Soil and Water C0ns_ 5:158-164, 198. I Smith, R. M., Thompson, D. 0., Collier, J. Hervey, R. J . 1954. Organic Matter, Crop Yields and in the Texas Blacklands. Soil f’ No. 5, Volume 77: ...... ..- ....... .. Sreenivas, L., Johnston, J . R., and Hill, H. ii i 1947. Some Relationships of Vegetation Q Detachment in the Erosion s Soil Sci. Soc. of Amer. Proc, 474. , Tippit, O. J., and Jones, J. H. 1953. Soil Conservation Management Sy Beef Production in the Black Texas. TAES Misc. Publicati i». Jhl- . _ "-, qu ‘e, ‘~ -<- »- .1 Yoder, R. E. I; 1936. A Direct Method of Aggregate .3 and a Study of the Physical i Erosion Losses. Jour. Am‘ Agron. 28:337-351. 1' Zingg, A. W. 1940. Degree and Length of Land S10“ Affects Soil Loss in Runoff. tural Engineering 21:3-8. A > "-- ion to Slope Length ;- Field-scale plots, O and P, were established in 1939. -= plots are 432 feet long and 151 feet wide. Indivi- il plots range from 1.39 to 3.01 percent slope. Thus, l: from these plots are not comparable directly with plot data. Moreover, cotton and corn on the field- ie plots have been bedded on the approximate contour ad of being planted essentially flat, as on the small ts. Other data and interpretations from this station V) indicate that contour bedding may reduce soil losses percent or more in small plots, especially on slopes of rcent or less and for storms of short duration and low nsity. This is about the maximum control from con- y-Hng reported by others (26). On field areas, where ‘touring is necessarily imperfect, the erosion control H of contouring appears to be smaller than indicated gsmall plot data. JAs an approximate check on likely slope length ef- J, it may be of value to compare the losses from the w scale and the small plots, with the best available 4 ctions for contouring and for slope percent (or degree . ope). Considering the 10-year period, 1942-51, the 12 6- runoff plots (432 feet long) showed an average an- p runoff of 2.0 inches and an annual soil loss of 3.7 l; per acre, on an average slope of 2.37 percent, while -- or cotton. During the same period, all of the small : in corn and cotton on a 4 percent slope of Austin , slope length 72.6 feet, gave average annual runoff _.1 inches and average soil loss of 11.7 tons per acre. i rotations were essentially the same on the small and W large plots. None of the corn or cotton was grown l grass sod. On the 72.6-foot plots with 4 percent y, the soil loss per inch of runoff was 2.9 tons per I’ on the 432-foot plots with 2.37 percent it was 1.9 ‘per inch of runoff. When corrected to a 4 percent p by the formula of Zingg (33) and confirmed by i: (26)—that soil loss is proportional to slope per- 1,50 the 1.4 power—the predicted soil loss for the 432- “plots, if on a 4 percent slope, would be 7.8 tons per tor 3.9 tons per inch of runoff, as compared with a w ed total soil loss of 11.7 tons per acre, or 2.9 tons (ch of runoff on the 72.6-foot plots. If a contour ation is credited with approximately a 50 percent re- (n in soil loss, the predicted loss for the 432-foot if planted flat to corn or cotton, becomes 15.6 tons ‘re. This credit to contour bedding and planting somewhat high because the contouring is not per- "=1 the furrows break in low spots, as is common for eas. These corrections for slope percentage and I touring place the soil losses on 432Y-foot plots in m order of magnitude as losses on 72.6-foot plots. p‘ might be considerably higher if runoff from the ~- was equal to that on the short plots, for erosion ‘h of runoff (with comparable slope) seems higher ' long than on the short plots. However. it is evi- - the time factor favors infiltration on long slopes. is more time for water to soak in as it flows over ' slope. This is, generally recognized (3, 6, 18, 26, \ i sidering absolute erosion per acre, a slope length ‘i 432:72.6, or 6. seems associated with a soil loss i, not more than 15.6:11.7, or 1.33. On this basis, 3; the length of a slope might be expected to in- (soil loss per acre by about 5 percent. an amount p‘ small compared to the error in most erosion “ments. Actually this amount is probably well the error of our corrections for slope percentage contouring. (the central Blackland area. on slopes of less than >5 percent, it often is observed that soil erosion is Appendix severe on the upper portion of slopes but is not evident in mid or lower-slope positions. It appears that colluvial deposits are common on long slopes on the uplands much farther up the heads of drainageways and further up on long slopes than is common in many humid areas farther east. Rills or small washes often occur close to the break from ridges to slopes even though there is no appreciable watershed above the wash to supply accumulated water.“ Blackland soil, when bare cultivated or fallow, is picked up quickly and easily by raindrop splash and by running water. The same tendency has been confirmed by de- tailed water drop studies (30). The same thing is sug- gested by the tendency toward formation of long, collu- vial slope deposits. on upper slopes, no additional soil detachment is likely down the slope unless slope degree increases. Moreover, as time permits extra infiltration on long slopes and re- duces runoff volume, the tendency would be for upper slope solids to be dropped on lower slopes even though no decrease in slope percentage occurs. These general observations and measurements as well as the data presented, are not considered precise or in- clusive enough to justify an absolute statement that sheet erosion is greater or less on long or on short slopes in this area. There is, perhaps, some evidence in favor of a slight increase in soil loss per acre with increasing slope length, as found at other locations. However, the expon- ent of 1.6 for C (slope length) in the formula by Zingg (33) is higher than indicated by average longtime small- plot data at this location. The longest record (21 years) with slope lengths indicates an exponent of 1.1. Shorter time periods indicate variable exponents from 0.9 to 2.4. Calculated comparisons from field-scale plots suggest an exponent of 1.1. Considering the several lines of evidence mentioned, it is apparent that factors sometimes consider- ed of minor importance, such as approximate contouring or slightly increased infiltration, can easily overshadow effects of slope length on sheet erosion on gentle slopes in the Blackland. In collecting basins, on the other hand, or where water becomes confined and forms gullies, the length of run may be much more important because of greatly increased volumes of water on the eroding area. Conclusions About Slope Length Small-plot studies over a 20-year period at Temple in- dicate that on the Blackland soils represented, on a 4 per- cent slope, soil erosion losses are influenced only to a very limited extent by length of slope. This small plot result is supported by data from large, field-scale plots and from observations on field areas. Factors thought to account for the small or insignifi- cant influence of slope length at Temple are: Increased time for infiltration on the low- er parts of long slopes which tends to decrease runoff on long slopes as compared with short slopes. Soil profiles with meduim or high water intake capacities during most rains. This is strongly influenced by shrinkage whenever the soil is below saturation as well as by soil structure and cropping practices. Surface soil which is easy to disperse and detach ( 30). thus permitting sheet water to pick up a full load in a short distance. “These observations are supported bv the observations and experience of W. R. Elder, soil scientist, SCS Operations, who has for several years studied this aspect of soil conservation in the Texas Black- lands. 39 If runoff water gets its load quickly Table 12. Rainiall summary by months and years. 1942-53. compared with the average from 1931-41. and the 41-year ave from 1913-53 Year Ian. Feb. Mar. Apr. May lune Iuly Aug. Sept. Oct. Nov. Dec. 1942 0.37 1.48 0.87 6.38 6.63 3.14 0.16 3.46 6.85 3.33 1.97 2.00 1943 0.92 0.02 3.26 1.53 3.52 1.08 5.36 0.36 3.53 1.19 1.75 1.97 1944 5.80 4.74 4.11 1.90 12.91 3.84 0.35 2.17 3.22 0.26 6.80 4.71 1945 2.98 5.26 2.85 7.74 2.42 4.39 0.23 4.18 1.74 3.33 0.61 2.93 1946 4.06 3.43 3.17 4.77 7.85 3.00 0.98 2.74 6.64 1.16 6.26 2.93 1947 4.52 0.62 3.48 4.43 5.25 0.50 0.95 3.94 0.45 0.23 2.01 2.62 1948 1.84 1.99 1.35 2.91 3.06 3.51 1.44 0.59 0.67 0.93 0.68 1.44 1949 3.29 2.11 3.01 6.53 0.50 5.30 2.37 0.59 1.36 4.92 0.10 3.48 1950 1.04 4.37 0.27 5.05 3.24 2.77 0.95 0.31 2.99 1.32 0.38 0.05 1951 1.59 2.64 1.69 2.72 7.39 2.54 0.10 0.04 6.27 1.66 1.09 0.41 1952 0.46 3.51 2.75 5.64 5.39 1.49 0.76 T 0.55 0.00 5.18 5.38 1953 0.97 1.23 1.66 2.61 7.72 1.03 2.48 2.57 2.18 8.44 1.40 2.62 1942-53-12-year average 2.32 2.62 2.37 4.35 5.49 2.72 1.34 1.75 3.04 2.23 2.35 2.55 1931-41—l1-year average 2.93 2.27 2.09 3.10 4.13 3.46 3.01 1.09 2.71 2.00 2.93 3.33 1913-53—4l-year average 2.53 2.34 2.26 4.16 4.77 2.78 1.85 1.92 3.36 2.83 2.84 2.90 Table 13. Average monthly temperatures‘ at Temple. Texas Monthly averages of daily temperatures 1913 to 1951 10-year average. 11-year average. 39-year average 39-year average 39-year average t Month 1942-51 1931-41 maximum minimum maximum 6. --- Ian. 48.4 49.8 59.9 36.7 48.3 Feb. 53.5 52.7 64.6 40.5 52.6 Mar. 59.6 59.9 71.8 46.4 59.1 Apr. 67.7 67.2 79.3 54.7 67.0 May 74.2 74.0 84.9 62.6 73.8 Iune 81.0 80.6 91.9 69.8 80.8 Iuly 84.0 83.4 95.5 72.0 83.8 Aug. 84.6 84.1 96.3 71.8 84.1 Sept. 78.2 79.5 90.2 66.6 78.4 Oct. 70.5 71.5 82.2 56.9 69.5 Nov. 59.7 57.7 70.4 45.9 58.2 Dec. 52.1 52.2 62.3 39.4 50.8 Annual average 67.8 67.7 79.1 55.3 67.2 1 Temperatures shown in degrees Fahrenheit. Table 14. Evaporation from a iree water surface‘ at Temple. Texas Extremes of absolute—daily evaporationiduring 37_years 10-year 11-year 37-year average. average. average. Maximum Minimum Month 1942-51 1931-41 1915-51 Year Day Amount Year Day Ian. 1.924 1.957 2.062 1938 31 0.310 1943 13 Feb. 2.250 2.403 2.537 1927 21 .523 1948 23 Mar. 4.020 4.348 4.184 1950 27 .440 1947 5 Apr. 4.490 5.219 4.888 1948 1 .662 1949 21 May 5.122 5.939 5.664 1929 2 .526 1942 18 Iune 6.409 6.825 6.899 1926 16 .479 1950 3 Iuly 7.520 7.568 7.895 1926 1 .588 1926 14 Aug. 7.915 7.635 7.871 1929 5 .525 1939 2 Sept. 5.650 6.094 5.890 1924 1 .457 1930 30 Oct. 4.323 4.681 4.567 1927 25 .516 1942 29 Nov. 3.329 3.012 3.061 1950 24 .347 1936 1 Dec. 2.262 2.201 2.220 1940 17 .553 1946 27 Annual average 55.314 57.882 57.738 1 Standard 6-foot diameter U.S. Weather Bureau pan. Table 15. Miles oi wind movement at Temple. Texas Extremes—38-year period 10- ear 11- ear 38-year . . . ' aveirage. avei-rage. average. Maxlmum Mlmmum Prev - '_ Month 1942-51 1931-41 1914-51 Year Day Movement Year Day Movement dire - Ian. 5256 5036 4732 1929 5 566 1928 l0 8 No ' Feb. 5011 5586 4834 1929 9 535 1923 11 15 No - Mar. 6204 6950 5985 1932 5 640 1925 24 13 So -, Apr. 5929 6233 5437 1936 6 563 1927 10 17 May 5260 5166 4618 1929 2 562 1915 17 17 Iune 5156 4458 4219 1928 18 436 1918 20 14 Iuly 4316 4035 3697 1939 3 390 1926 29 8 Aug. 4479 3925 3603 1915 17 482 1926 1 ll Sept. 3913 3990 3372 1939 29 450 1927 27 9 Oct. 4084 4320 3627 1926 13 563 1924 22 5 Nov. 4766 4931 4161 1929 13 530 1926 10 4 Dec. 4890 4941 4450 1940 27 492 1927 24 16 Annual average 59264 59571 52735 " Extremes March 5. 1932——640 Nov. 4. 1 40 l6. Record of amount and intensities of all individual storms of 1.0 inch or more. 1942-53. at the Blackland station. Temple. Texas. These storms which amount to about 50 percent oi the total rainfall. caused more than 75 per- cent ot the total water and soil losses Maximum intensities Maximum intensities 5-minute l5-minute 30-minute 2-hour S-minute 15-minute 30-minute 2-hour Amount period period period period Date Amount period period period period Inches — — — — Inches per hr. — — — — Inches — — — — Inches per hr. — — — — I 1947 » 7.5 2.55 2.40 1.55 1.14 0.55 Ian. 17 1.24 0.45 0.40 0.54 0.15 2.2525 2.25 2.75 1.52 0.95 0.55 Mar. 15 1.40 0.95 0.54 0.52 0.55 7.5 1.57 1.50 1.50 1.42 0.45 Apr. 12 1.55 5.50 2.55 1.45 0.57 .11 1.19 4.52 1.54 0.95 0.27 Apr. 19 1.55 7.20 4.40 5.24 0.54 15.111 5.15 5.24 2.54 2.24 1.22 May 9 1.00 1.20 0.75 0.44 0.27 ' 0 1.21 5.12 2.00 1.90 1.50 May 15 1.45 5.00 4.05 2.45 0.72 3.10.11 1.07 1.05 0.55 0.52 0.55 May 20 1.55 4.50 4.00 2.55 0.55 1'15 1.57 5.00 4.25 2.70 0.75 Aug. 15 1.15 4.20 2.50 1.95 0.55 ".7-5-9 5.17 5.50 2.55 2.15 0.55 Aug. 25 1.55 1.20 0.72 0.52 0.25 9-20 1.59 2.15 1.44 1.52 0.45 1948 Apr. 15 1.25 2.04 1.20 1.20 0.44 ‘.24 2-38 334 258 232 [L91 Apr. 25 1.01 1.20 0.92 0.64 0.25 18 L51 2A0 L36 L08 [L36 May 18 1.33 2.40 2.00 1.80 0.67 yuan L62 L92 [L96 [L70 0.31 Iune 28 3.20 3.60 2.56 2.48 1.48 40-11-12 3.29 3.60 2.88 1.80 0.75 1949 l” 1-65 1-"8 "-88 0-95 "-41 Feb. 25 1.15 0.50 0.40 0.25 0.27 '25-25-27.25-29 5.00 1.55 1.54 0.90 0.55 Man 21 L97 334 m4 ZJQ L95 12-13 1-15 1-32 1-24 1-22 "-44 Apr. 24 2.42 4.55 5.24 2.12 0.72 .26 1-118 "-69 "-48 "-38 9-21 Apr. 25 1.59 4.05 2.75 1.44 0.57 - Iune 14 2.55 5.50 5.24 2.50 0.55 V 2m ‘L84 052 0A2 M6 Iune 22 1.52 5.95 5.04 2.52 0.51 < 1a1y 51 1.25 5.00 1.75 1.25 0.51 1'14 1'24 0'00 0'24 0'20 0'00 Oct 21 117 2.25 1.44 0.92 0.55 1'04 0'00 0'00 0'42 0'02 Oct. 24 2155 5 12 2 00 2.00 0.95 1.45 2.75 2.12 1.45 0.45 ' ' ' ' 1.05 2.40 1.55 0.95 0.55 1950 '15 1.42 5.50 2.12 1.50 0.52 Feb. 9 1.19 1.55 0.50 0.55 0.24 w 1.12 1.50 1.55 1.05 0.47 Feb. 12 1.40 4.44 5.52 2.05 0.55 1.50 1.55 1.45 1.12 0.40 Apr. 15 1.15 1.05 0.75 0.55 0.55 2.22 5.00 2.05 1.40 0.79 Apr. 15 2.05 4.55 2.40 1.55 0.57 5.52 5.00 5.50 5.10 1.05 May 15 1.14 4.50 5.54 2.05 0.57 1.07 5.24 2.52 1.50 0.45 Iune 5 1.55 1.20 0.72 0.55 0.25 1.04 1.55 1.20 1.20 0.44 Sept. 10 1.55 5.00 4.00 2.44 0.51 1.02 2.04 0.92 0.55 0.24 Oct. 19 1.24 0.50 0.45 0.55 0.24 1.02 5.25 5.04 1.72 0.51 1951 2'10 2'00 2'00 2'20 0'01 Ian. 15 1.27 4.50 2.55 1.50 0.59 1'45 2'40 1'04 1'08 0'70 Feb. 15 1.55 2.40 1.00 0.55 0.42 1'11 2'00 1'52 0'02 0'41 Apr. 29 1.72 2.40 1.75 1.44 0.75 1'70 0'90 0'50 0'40 0'20 May 15 1.59 2.55 1.92 1.50 0.72 1'22 0'40 0'24 0'10 0'11 Iune 5 1.05 0.45 0.40 0.52 0.21 2'00 2'00 2'00 1'40 0'00 Sept. 15 5.05 4.20 5.50 5.50 1.45 1-92 1'92 1'04 1'20 0'02 Sept. 25 1.55 4.55 2.50 1.95 0.57 Oct. 25 1.27 1.44 1.25 0.92 0.49 1.55 1.05 0.75 0.54 0.55 1952 m5 L44 L03 (L72 OJQ Feb. 24-25 1.41 0.72 0.45 0.40 0.22 L22 L44 [L92 [L92 [L41 Mar. 9-10 1.26 2.88 2.28 1.28 0.40 5J9 432 L92 2373 L35 Apr. ll 1.17 1.44 0.72 0.48 0.32 L55 L53 L40 L24 (L53 Apr. 19-20 1.26 1.68 0.88 0.64 0.21 L15 336 Z32 L44 [L45 Apr. 21-22 1.87 1.08 0.88 0.64 0.38 L03 L36 M8 M0 M3 May 17-15 2.10 4.05 2.24 1.52 0.40 L51 2_ 16 L12 0.70 M; May 24-25 2.01 5.55 2.05 1.52 0.55 May 27-25 1.12 0.45 0.40 0.55 0.14 Oct. 22-25-24 5.75 2.40 1.55 1.55 0.57 5:111:11: 1:: 2:2: 1;: $1.: :1: 3:4; 522g [11:22 E24; Dec. 29-50 2.15 1.55 0.54 0.25 0.20 1.55 2.55 2.00 1.45 0.55 1953 1.10 0.48 0.32 0.32 0-21 Mar. 5-9-10-11 1.01 0.50 0.40 0.40 0.15 1.06 2.64 1.60 1.20 0.48 Apr. 25-24 1.50 2.15 1.44 1.25 0.45 2.79 7.44 6-08 3.40 0.99 May 11 5.55 4.50 2.15 1.44 0.90 1.04 3.60 1.80 1.22 0.52 May 14-15 2.00 2.54 2.15 1.25 0.52 1.56 3.60 3.16 1.92 0.62 Iune 12 1.05 2.40 1.92 1.45 0.51 1.38 2.40 1.76 1.06 0.42 Iuly 12 1.25 5.50 5.55 2.44 0.52 2.52 1.92 1.72 1.54 0.75 Aug. 19-20 2.42 1.92 1.55 0.95 0.55 1.55 5.00 ' 2.15 1.54 0.55 Sept. 5 1.27 4.05 5.20 1.54 0.50 1.45 5.55 2.55 1.55 0.55 Oct. 22-25 5.50 5.12 1.44 1.12 0.50 2.41 4.52 5.50 2.90 1.20 Oct. 25-25 4.50 4.05 2.72 2.55 0.92 1.05 1.52 0.92 0.72 0.25 Nov. 5 1.20 0.50 0.55 0.40 0.15 1.44 2.25 1.05 0.74 0.57 Dec. 1 - 1.55 0.95 0.54 0.54 0.52 Table 17. Annual summary of rainfall. runoff and soil loss for all areas under measurement at the Blackland E i“ Station, Temple. Texas. 1931-51 ' Yield of Depth Soil Plot or Plot or watershed Winter Crop crop Rain- of loss per watershed characteristics and treatments Year cover harvestedl per acre fall runoff acre i Bu. or lbs. — — Inches — — — — — Tons " 1931 Corn 32 bu. 23.4 0.7 4.9 1932 do 27 1.3 4.1 19.8 1933 do 24 25.7 5.5 19.9 1934 do 11 29 7 5.4 33.8 1935 do 29 46 7 9.2 44.7 1936 do 32 39.9 7.4 39.3 Area 1/200 acre. 6 by 36.3 feet. 1937 do 36 28.6 1.3 4.4 Land slope. 4 percent. 1938 do 28 27.6 2.6 7.5 Soil. Austin clay. 1939 do 29 23.8 2.9 11.1 Cropping practice. continuous corn with 1940 do 13 39.9 7.4 9.4 1 furrows and rows down slope. 1941 do 4 43.8 10.1 33.9 Planted flat without bedding. 1947-52. 1942 do 8 36.1 9.4 12.5 In Iuly 1951 a 4-ton mulch of straw was applied. 1943 do 26 24.6 2.3 3.7 There was no runoff after mulching. 1944 d0 l4 50.1 8.8 14.3 1945 do 25 37 2 5.1 5.3 1946 do 29 45 8 8.5 14.1 1947 do 23 27 2 4.4 8.3 1948 do 19 19 0 2.2 1.8 1949 do 27 32.3 6.5 4.0 1950 do 22.4 2.4 1.6 do 20 18.6 2.9 2.7 201/2—year average . . . . . . . . . . . . . . . . . . . . . . . 32.9 5.3 14.5 1931 Corn 32 bu 23.4 0.7 1.6 1932 do 26 31.3 3.3 20.6 Area 1/50 acre. 6 by 145.2 feet. 1933 do 26 25.7 3.6 11,8 Land slope. 4 percent. 1934 do 11 29.7 4.6 27,3 2 Soil. Austin clay. 1935 do 33 46.7 7.0 31.4 Cropping practice. continuous corn. with furrows 1936 do 29 39.9 7.5 37,6 and rows down slope. 1931-44. 1937 do 33 28.6 0.7 3.1 . 1938 do 26 27.6 1.9 9.4 1939 do 29 23.8 1.6 6.3 1940 do 12 39.9 6.9 14.6 1941 do 22 43.8 8.3 43.6 1942 do 5 36.1 7.2 22.3 1943 Corn 31 bu 24.6 1.8 4.1 1944 l/z Year do 32.7 8.1 27.7 l31/z-year average . . . . . . . . . . . . . . . . . . . . . . . 33.6 4.7 19,4 1945 Cotton 263 lbs. 37.2 4.3 7,7 Since 1944. rotation. cotton. Hubam. with 1946 Hubam 1296 45.8 0,5 0,3 rows down slope or flat. 1947 Cotton 208 27.2 2.3 3,3 Since 1946. all crops were planted flat without 1948 Hubam 210 19.0 0.2 0,0 furrows. 1949 Cotton 461 32.3 2.9 2.3 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 2.0 2,7 Since 1949. rotation. corn. oats. planted flat. 1950 Oats 22.4 0.4 0.2 1951 Corn 60 bu. 27.7 2.9 1.9 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 1.6 1,0 1931 Corn 38 bu 23.4 1.0 2.5 , 1932 do 8 31.3 3.5 19.0 1933 do 29 25.7 4.8 14.7 ‘ 1934 do 14 29.7 4.8 39.2 Area 1/100 acre. 6 by 72.6 feet. 1935 do 33 46.7 7.4 29.1 e Land slope. 4 percent. 1936 do 36 39.9 6.5 38.6 i 3 Soil. Austin clay. 1937 do 30 28.6 1.1 4.2 , Cropping practice. continuous corn. with 1938 do 32 27.6 2.3 12.6 I furrows and rows down slope. 1939 do 39 23.8 2.7 14.2 1940 do 12 39.9 6.6 13.7 i 1941 do 26 43.8 8.4 38.8 ’ 1942 do 7 36.1 8.4 22.0 '" 1943 do 32 24.6 2.2 4.5 1944 do 19 50.1 7.9 24.8 i 1945 do 21 37.2 4.1 7.5 Y 1946 do 28 45.8 8.5 20.4 7. Since 1946. planted flat with no furrows. 1947 Corn 29 bu. 27.2 4.0 11.7 ' 1948 do 11 19.0 2.2 3.0 7 1949 do 30 32.3 6.3 10.4 , 5-year average (1945-1949) . . . . . . . . . . . . .. 32.3 5.0 10.6 - 1950 do 22.4 3.1 2.4 ‘ 1951 do 26 27.7 4.4 4.2 #1 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 3.8 3.3 f 21-year average (1931-1951) . . . . . . . . . . . . .. 32.5 4.8 16.1 f 1931 Corn 36 23.4 0.5 0.8 ‘ 1932 Oats Oats 75 31.3 0.0 0.0 . 1933 Cotton 335 lbs. 25.7 2.4 5.2 1' 1934 Corn 18 bu. 29.7 ' 3.9 22.6 7 Area 1/100 acre. 6 by 72.6 feet. 1935 Oats Oats 46 bu. 46.7 0.1 0.4 . Land slope. 4 percent. 1936 Vetch Cotton 240 lbs. 39.9 7.9 54.9 4 Soil. Austin clay. 1937 Vetch Corn 38 bu. 28.6 1.9 5.5 ,- Cropping practice. rotation cotton. corn. oats. 1938 Oats Oats 67 27.6 0.1 0.1 _| Rows down slope. 1939 Cotton 237 lbs. 23.8 2.0 7.3 ’ 1940 Corn 14 bu. 39.9 6.2 13.7 Y7 1941 Oats Oats 72 43.8 0.6 0.3 .1" 1942 Cotton 273 lbs. 36.1 4.8 11.9 e 1943 Corn 43 bu. 24.6 1.4 2.6 Q 1944 Oats Oats 32.7 0.1 0.1 i. 131/z-year average . . . . . . . . . . . . . . . . . . . . . . . 33.6 2.4 9.3 , 1945 Cotton 320 lbs. 37 2 2.4 3.8 ' Since 1944. rotation cotton. oats (H). 1946 Oats (H) 35 bu. 45.8 0.1 0.2 rows down slope or flat. 1947 Cotton 300 lbs. 27.2 3.3 16.5 1948 Oats (H) 26 bu. 18.9 0.6 0.6 1949 Cotton 342 lbs. 32 3 3.6 17.1 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32 3 2.0 7.6 qHTl-‘Iubam; (E) Evergreen; (C) Sweetclover. 42 :17. Annual summary of rainfall. runoff and soil loss for all areas under measurement at the Blackland Experiment Station. Temple. Texas. 1931-51 (Continued) Yield of Plot or watershed Winter Crop crop Rain- characteristics and treatments Year cover harvested per acre fall Bu. or lbs. — — Inches — — — — — Tons — -— — Since 1949. rotation oats (H). corn planted flat. 1950 Oats (H) 22.4 1. 3.1 1951 Corn 56 bu. 27.7 2. 1.2 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 1. 1.5 1931 Corn 34 23.4 0. 2.9 1932 Oats Oats 57 31.3 0. 2.3 1933 Cotton 361 lbs 25.7 3. 3.7 1934 Corn 15 bu. 29.7 13. 0.4 Area 1/100 acre. 6 by 72.6 feet. 1935 Oats Oats 40 46.7 0. 0.9 Land slope. 4 percent. 1936 Cotton 320 lbs. 39.9 15. 0.4 Soil. Austin clay. - 1937 Corn 29 bu. 28.6 2. 2.6 Cropping practice. rotation cotton. corn. oats. 1938 Oats Oats 50 27.6 0. 1.1 l93l rows down slope. 1939 Cotton 212 lbs. 23.8 0. 3.6 Rows on contour. 1932-44. 1940 Corn 13 bu. 39.9 5. 1.2 1941 Oats Oats 61 bu. 43.8 0. 0.4 1942 Cotton 251 lbs. 36.1 2. 1.3 1943 Corn 38 bu. 24.6 2. 2.3 1944 Oats Oats 32.7 0. 0.4 l31/2-year average . . . . . . . . . . . . . . . . . . . . . . . 33.6 3. 2.4 1945 Cotton 301 lbs. 37.2 7. 1.9 1946 Oats 31 bu. 45.8 0. 1.1 Since 1944. crop rotation cotton. oats 1947 Cotton 252 lbs 27.2 16. 0.5 rows down slope or flat. 1948 Oats 28 bu. 18.9 0. 0.7 1949 Cotton 352 lbs. 32.3 13. 0.4 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 7. 3.2 Since 1949. crop rotation corn. oats (E) 1950 Oats (E) 22.4 0. 1.6 planted flat. ~ 1951 Corn 51 bu. 27.7 3. 1.2 2-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 25.1 2. 1.3 1931 Grass None None 23.4 (2 1932 do do do 31.3 (2 1933 do do do 25.7 (2 1934 do do do 29.7 (2 Area 1/ 100 acre. 6 by 72.6 feet. 1935 do do do 46.7 0. 2.4 Land slope. 4 percent. 1936 do do do 39.9 0. 1.4 Soil. Austin clay. 1937 do do do 28.6 (2 Cropping practice. continuous Bermudagrass. 1938 do do do 27.6 0. 2.8 clipped. 1939 do do do 23.8 0. 5.0 1940 do do do 39.9 (2 1941 do do do 43.8 0. 0.2 1942 do do do 36.1 0. 0.1 1943 do do do 24.6 1944 do do do 50.1 0. 0.1 1945 do do do 37.2 0. 0.1 1946 do do do 45.8 U. 0.2 1947 do do do 27.2 1948 do do do 19.0 1949 do do do 32.3 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 0.1 1950 do do do 22.4 1951 do do do 27.7 2-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 25.1 21-year average . . . . . . . . . . . . . . . . . . . . . . . . . 32.5 0. 0.2 1931 Cotton No rec. 23.4 0. 2.2 1932 Corn 32 bu. 31.3 19. 0.6 1933 Oats Oats 20 25.7 0. 1.0 1934 Cotton 250 lbs. 29.7 19. 0.4 1935 Vetch Corn 36 bu. 46.7 37. 0.5 Area 1/100 acre. 6 by 72.6 feet. 1936 Oats Oats 38 39.9 p_ 3. 2.8 Land slope. 4 percent. 1937 Vetch Cotton 344 lbs. 28.6 5. 5.1 H Soil. Austin clay. _ 1938 Corn 34 bu. 27.6 14. 0.6 4 Croopping practice. rotation cotton. corn. 1939 Oats Oats 58 23.8 0. 1.7 " oats. Rows down slope. 1940 Cotton 302 lbs. 39.9 13. 0.2 1941 Corn 34 bu. 43.8 26. 0.3 1942 Oats Oats 10 36.1 0.1 0.4 1943 Cotton 463 lbs. 24.6 3.3 1.8 1944 Corn 32.7 35.6 0.4 l31/2-year average . . . . . . . . . . . . . . . . . . . . . . 33.6 13.3 0.4 1945 Oats 39 bu. 37.2 0.4 0.2 Since 1944. crop rotation cotton. oats. 1946 Cotton 92 lbs 45.8 34.4 0.6 rows down slope or flat. 1947 Oats 17 bu. 27.2 1.0 0.7 1948 Cotton 216 lbs 19.0 - 9.6 3.8 1949 Oats 70 bu. 32.3 0.5 0.5 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 9.2 3.5 Since 1949. crop rotation corn. oats (E) 1950 Corn 22.4 0.8 1.7 planted flat. 1951 Oats 27.7 0.2 0.8 . 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.5 1.3 1931 Corn 34 bu. 23.4 0.7 1.6 1932 Oats Oats 71 31.3 0.4 4.4 _ 1933 Cotton 300 lbs 25.7 7.9 3.4 ‘ 1934 Corn 16 bu. 29.7 15.7 0.4 i Area 1/100 acre. 6 by 72.6 feet. 1935 Oats Oats 49 46.7 0.8 1.0 9 Land slope. 4 percent. 1936 Cotton 270 lbs. 39.9 53.3 0.7 ‘* Soil. Austin clay. _ 1937 orn 32 bu. 28.6 6.3 3.1 Cropping practice. rotation cotton. corn. oats. 1938 Oats Oats 48 bu. 27.6 0.1 0.7 1931 rows on contour. 1939 Cotton 263 lbs. 23.8 8.1 4.2 1932-41 rows down slope. 1940 Corn 15 bu. 39.9 18.1 0.2 1941 Oats Oats 66 43.8 0.4 3.7 1942 Cotton 257 lbs. 36.1 11.1 0.2 1943 Corn 41 bu. 24.6 2.8 2.1 1944 Oats Oats 32.7 0.2 0.5 l3l/g-year average . . . . . . . . . . . . . . . . . . . . . . . 33.6 9.3 3.7 Table 17. Annual summary of rainfall. runoff and soil loss for all areas under measu rement at the Blackland ~-_ ,1» ‘ Station. Temple. Texas. 1931-51 (Continued) ’ ¢ Yield oi Depth Soil Plot or Plot or watershed Winter Crop crop Rain- o loss per watershed characteristics and treatments Year cover harvested per acre fall runolf acre Bu. or lbs. — — Inches -— — —- — — Toni 1945 Oats 30 bu. 37.2 0.9 0.1 _ 1946 Cotton 107 lbs. 45.8 4.8 18.8 Since 1944. crop rotation cotton. oats (H). 1947 Oats 21 bu. 27.2 0.8 0.9 rows down slope or ilat. 1948 Cotton 250 lbs. 19.0 2.5 6.9 1949 Oats 78 bu. 32.3 0.5 0.3 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 1.9 5.4 Since 1949. crop rotation corn. oats (H) 1950 Corn 22.4 0.4 0.4 planted flat. 1951 Oats (H) 27.7 0.0 0.0 Z-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.2 0.2 1931 Oats Oats No rec 23.4 0.1 0.2 1932 Cotton do 31.3 2.2 9.2 1933 Corn 26 bu. 25.7 3.7 11.5 1934 Oats Oats 13 29.7 0.5 1.0 1935 Vetch Cotton 360 lbs 46.7 6.5 27.3 Area 1/100 acre. 6 by 72.6 ieet. 1936 Corn 45 bu. 39.9 8.6 52.5 Land slope. 4 percent. 1937 Oats Oats 36 28.6 1.7 2.9 9 Soil. Austin clay. 1938 Cotton 340 lbs. 27.6 3.9 16.0 Cropping practice. rotation cotton. corn. oats. 1939 Corn 45 bu. 23.8 2.5 11.8 Rows down slope. 1940 Oats Oats 22 39.9 7.3 13.5 1941 Cotton 540 lbs 43.8 7.6 30.4 1942 Corn 7 bu. 36.1 7.8 20.7 1943 Oats Oats 32 bu. 24.6 0.0 0.0 1944 (1/z Year) Cotton 32.7 10.2 35.9 131/z-year average , . . . . . . . . . . . . . . . . . . . . . . 33.6 4.6 17.3 1945 Hubam 965 lbs. 37.2 2.7 1.2 1946 Cotton 90 45.8 5.6 21.7 Since 1944. crop rotation cotton. Hubam 1947 Hubam 410 27.2 1.2 0.8 rows down slope or flat. 1948 Cotton 241 19.0 1.2 2.8 1949 Hubam 240 32.3 0.6 0.7 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 2.2 5.4 Since 1949. crop rotation corn. oats. 1950 Corn 22.4 0.2 0.4 planted flat. 1951 Oats 27.7 0.0 0.0 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.1 0.2 1931 Corn 30 bu. 23.4 0.3 0.4 1932 Oats 64 31.3 0.0 0.0 1933 Oats Vetch A._W. peas Vetch Cotton 311 lbs. 25.7 0.7 0.8 1934 Corn 16 bu. 29.7 2.9 6.7 Area 1/100 acre. 6 by 72.6 feet. 1935 Oats Oats 57 46.7 0.0 0.1 Land slope. 4 percent. 1936 Vetch Cotton 345 lbs. 39.9 4.6 11.1 10 Soil. Austin clay. 1937 Corn 27 bu. 28.6 1.3 2.0 Cropping practice rotation cotton. corn. oats. 1938 Oats Oats 63 27.6 0.1 0.0 Rows on contour from 1931-44. 1939 Cotton 333 lbs. 23.8 0.2 0.6 1940 Corn 13 bu. 39.9 5.8 7.4 1941 Oats Oats 27 43.8 1.7 0.3 1942 Cotton 252 lbs. 36.1 2.7 4.6 1943 Corn 44 bu. 24.6 1.1 2.3 1944 (1/2 year) Oats 32.7 0.2 0.1 131/z-year average . . . . . . . . . . . . . . . . . . . . . . . 33.6 1.6 2.7 1945 Corn 29 bu. 37.2 2.7 4.2 1946 Cotton 69 lbs 45.8 5.1 24.9 Since 1944. crop rotation cotton. corn. 1947 Corn 17 bu. 27.2 2.7 12.2 rows clown slope or flat. 1948 Cotton 150 lbs 19.0 2.2 7.6 1949 Cotton 256 32.3 2.9 13.6 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 3.1 12.5 Crop rotation continuous oats (E). 1950 Oats (E) 22.4 0.5 0.7 1951 Oats (E) 27.7 0.0 0.0 Z-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.3 0.4 1931 Corn 8 bu. 23.4 0.3 , 0.4 1932 Oats Oats 23 31.3 0.7 1.2 1933 Cotton 93 lbs. 25.7 5.5 30.4 1934 Corn 00 29.7 3.9 11.7 Area 1/100 acre. 6 by 72.6 feet. 1935 Oats Oats 22 bu. 46.7 9.5 7.1 Land slope. 4 percent. 1936 Cotton 110 lbs. 39.9 9.6 60.1 11 Soil. Austin clay: top 15 inches removed. 1°37 Corn 12 bu. 28.6 3.0 10.3 Cropping practice rotation. cotton. corn. oats. 1938 Oats Oats 30 27.6 5.4 4.5 Rows down slope or flat. 1939 Cotton 122 lbs. 23.8 3.0 15.4 - 1940 Corn 6 bu. 39.9 10.7 19.0 1941 Oats Oats 22 43.8 11.5 7.2 1942 Cotton 55 lbs. 36.1 7.9 20.5 1943 Corn 12 bu. 24.6 2.9 4.3 1944 Oats Oats 32.7 3.5 0.6 131/z-year average . . . . . . . . . . . . . . . . . . . . . . . 33.6 5.7 14.3 1945 Hubam 340 lbs. 37.3 3.2 2.3 1946 Cotton 22 45.8 9.6 29.0 Crop rotation cotton. Hubam. 1947 Hubam 180 27.2 3.7 3.4 1948 Cotton 8 19.0 2.7 6.9 1949 Hubam 90 32.3 6.6 8.7 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 5.1 10.1 Crop rotation continuous oats (E). 1950 Oats (E) 22.4 1.1 0.5 1951 Oats (E) 27.7 0.1 0.1 Z-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.6 0.3 1931 1932 Cotton (3) Cane (3) 20.5 (1) (1) 1933 Cotton (3) Sudan (3) 25.7 (l) (2) 44 .1 Annual summary of rainfall. runoff and soil loss for all areas under measurement at the Blackland Experiment Station. Temple, Texas. 1931-51 (Continued) Soil loss Yield of Depth Soil per acre Plot or watershed Winter Crop crop Rain- of loss per inch of characteristics and treatments Year cover harvested per acre fall runoff acre runoff Bu. or lbs. — — Inches — — -— —- —- Tons — — — 1934- Cotton (3) Oats Oats (3) 29.7 (1) (2) Area 0.0463 acre. 12 by 168 feet. 1935 Cotton 317 lbs Land slope. 31/; percent. Oats Oats 42 bu 46.6 0.2 0.1 0.3 Soil. Austin clay. 1936 Cotton 217 lbs _ Cro ping practice. strip-cropped. beginning at Cane 3) 39.9 1.3 3.3 2.5 ottom of plot. 1937 Cotton 212 lbs 24-foot resistant crop, 60-foot cotton. Sudan 3 tons 28.6 0.1 0.3 2.1 24-foot resistant crop. 60-foot cotton. 1938 Cotton 241 lbs Rows on contour. 1931-44. Oats Oats 65 bu. 27.6 0.2 0.2 1.1 1939 Cotton 203 lbs Cane 5 tons 23.8 0.2 0.7 4.5 1940 Cotton 252 lbs Sudan 3 tons 39.9 0.5 0.7 1.3 1941 Cotton 324 lbs Oats Oats 61 bu. 43.8 0.3 0.2 0.8 1942 Cotton 211 lbs Cane 5 tons 36.1 1.4 2.1 1.5 1943 Cotton 408 lbs Sudan 2 tons 24.6 0.1 0.1 1944 (1/2 year) Cotton Oats 32.7 2.5 2.1 0. l2l/z-year average . . . . . . . . . . . . . . . . . . . . . . . 34.5 0.6 0.8 1.4 1945 Alfalfa 1 ton 37.2 3.2 3.0 0.9 1946 Cotton 122 lbs. 45.8 3.8 19.4 5.0 Since 1944. crop rotation cotton. oats. alfalfa. 1947 Oats 36 bu. 27.2 0.3 0.2 0.8 Rows down slope or flat. 1948 Alfalfa 1 ton 19.0 0.4 0.8 2.0 1949 Cotton 451 lbs. 32.3 1.5 4.5 3.1 S-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 1.8 5.6 3.1 Crop rotation corn. oats (E). 1950 Corn 22.4 1.4 4.2 2.9 1951 Oats (E) 44 bu. 27.7 0.1 0.1 1.2 Z-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.8 2.2 2.8 1931 1932 Cotton (3) 20.5 1.6 3.7 2.3 1933 do (3) 25.7 1.7 1.8 1.1 1934 do (3) 29.8 0.0 0.2 6.3 1935 do 282 lbs 46.7 3.8 14.6 3.8 Area 0.0847 acre. 22 x 168 feet. 1936 do 222 39.9 3.9 18.7 4.7 Land slope. 31/; percent. 1937 do 218 28.6 0.0 0.1 2.9 Soil. Austin clay. 1938 do 250 27.6 1.6 8.8 5.4 Cropping practice. continuous cotton. 1939 do 210 23.8 0.7 2.4 3.5 Hows on contour. 1931-44. 1940 do 213 39.9 0.2 0.6 2.9 1941 do 320 43.8 1.5 6.1 4.0 1942 do 244 36.1 2.4 3.9 1.6 1943 do 506 24.6 0.0‘ T 1944 do 170 50.1 6.9 22.8 3.3 1945 do 222 37.2 2.7 11.0 4.1 1946 do 111 45.8 3.6 13.3 3.8 Since 1844. rows down slope or flat. 1947 do 229 27.2 3.4 10.5 3.1 1948 do 220 19.0 2.2 5.0 2.3 1949 do 328 32.3 2.3 8.1 3.5 S-year average . . . . . . . . . . . . . . . . _ _ _ , , , _ _ _ _ 32,3 2,8 9,6 3_4 l7l/g-xear average . . . . . . . . . . . . . . . . . . . . . .. 33.9 2.2 7.5 ' 3.4 _ 19 Oats (E) 22.4 0.7 0.7 0.9 Crop rotation corn. oats (B). oats (E). 1 1 Oats (E) 27.7 0.0 0.0 0.2 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.4 0.3 0.9 133i 3 CONOI! ( ) 20.5 0.8 13.7 16.7 1933 do (3) 25.7 4.1 6.4 1.6 1934 do (3) 29.7 5.2 13.4 2.5 1935 do 226 lbs 46.7 7.5 23.9 3.2 Area 0.0309 acre. 8 x 168 feet. 1936 do 230 39.9 7.7 31.7 4,1 Land slope. 31/2 percent. 1937 do 302 28.6 0.3 0.4 1.4 Soil. Austin clay. 1938 do 227 27.6 3.1 12.0 3.8 Cropping practice continuous cotton. 1939 do 187 23.8 2.3 7.3 3.2 Rows down slope or flat. 1940 do 207 39.9 6.1 14,0 2,3 1941 do 288 43.8 7.3 29.2 4.0 1942 do 218 36.1 2.7 6.3 2.3 1943 do 412 24.6 1.8 3.0 1.7 1944 do 140 50.1 9.8 26.8 2.7 1945 do 164 37.2 5.1 13.1 2.6 1946 do 49 45.8 7.1 19.4 2.7 1947 do 202 27.2 3.2 8.1 2.5 1948 do 189 19.0 2.3 10.7 4.6 1949 do 281 32.3 3.6 7.7 2.2 S-Year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 4.3 11.8 2.8 171/z-year average . . . . . . . . . . . . . . . . . . . . . . . 33.9 4.5 14,0 3_1 Since 1949. crop rotation corn. oats 1950 Oats 1:‘. 22,4 _ with Evergreen clover. 1951. Corn( ) 44 bu. 27.7 Z-year average . . . . . . . . . . . . . . . . . . . . . . . .. 25.1 0.4 0.3 0.8 1931 . 1932 Cotton (3) Area 0.0847 acre. 22 by 168 feet. Cqne (3) 205 (l) (2) Land slope. 31/2 percent. 1933 Cotton (3) Soil. Austin clay. _ Oats Oats (3) 25.7 ( 1) (2) Cropping practice. strip-cropped 1934 Cotton (3) beginning at bottom of plot. Guar (3) 29.7 0.0 0,3 13,0 24 feet resistant crop. 60 feet cotton, 24 feet 1935 C911“; 24g 11,5 resistant crop. 60 feet cotton. Sudan (3) 46.7 2.0 1,9 0,9 Rows on contour. 1931-44. 1936 Cotton 225 Oats Oats 46 bu 39.9 1.4 1.3 0.9 45 Table 17. Annual summary of rainfall. runoff and soil loss for all areas under measurement at the Blaclcland Station, Temple. Texas. 1931-51 (Continued) Yield of Depth Soil Plot or v Plot or watershed Winter Crop crop Rain- of loss per watershed characteristics and treatments Year cover harvested per acre fall runoff acre Bu. or lbs. — — Inches — — - -— — To 1937 Cotton 262 lbs. Sudan 3 tons 28.6 0.3 0.7 1938 Cotton 221 lbs. Cane 6 tons 27.6 1.2 2.7 1939 Cotton 186 lbs. Oats Oats 25 bu. 23.8 0.0 0.0 1940 Cotton 207 lbs. Cane 6 tons 39.9 0.2 0.2 1941 Cotton 286 lbs. Sudan 3 tons 43.8 0.8 1.8 1942 Cotton 234 lbs. Oats Oats No yld. 36.1 1.0 0.7 1943 Cotton 446 lbs. Cane 3 tons 24.6 0.1 0 1 1944 Cotton Sudan 32.7 5.7 0.0 121/2-year average . . . . . . . . . . . . . . . . . . . . .. 31.1 1.1 1.5 1945 Oats 40 bu. 37.2 0.9 0.1 1946 Alfalfa 2 tons 45.8 2.2 0.9 Since 1944. crop rotation cotton. oats. 1947 Cotton 225 lbs. 27.2 2.7 5.3 alfalfa. Rows down slope or flat. 1948 Oats 47 bu. 19.0 0.3 0.2 1949 Alfalfa 1 ton 32.3 0.3 2.1 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . 32.3 1.3 1.7 Crop rotation corn. oats (E). oats (E). 1950 Corn 22.4 0.8 1.1 1951 Oats (E) 27.7 0.1 0.0 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.4 0.6 1932 Cotton (3) Sudan (3) 20.5 (1) (2) 1933 Cotton (3) Oats Oats (3) 25.7 (1) (2) 1934 Cotton (3) Sudan (3) 29.7 0.1 0.2 1935 Cotton 220 lbs. Cane (3) 46.7 1 1 0.9 1936 Cotton 221 lbs. Sudan (3) 39.9 1.1 0.6 1937 Cotton 438 lbs. Oats Oats 22 bu. 28.6 0.1 0 l Area 0.0503 acre. 13 by 168 feet. 1938 Cotton 217 lbs. Land slope. 31/2 percent. I Sudan 5 tons 27.6 0.8 1.4 16 Soil. Austin clay. 1939 Cotton 189 lbs. Cropping practice. strip-cropped Sudan 3 tons 23.8 0.1 0.2 beginning at bottom of plot. 1940 Cotton 245 lbs. 24 feet resistant crop. 60 feet cotton. 24 feet Oats Oats 14 bu. 39.9 0 5 0.6 resistant crop. 60 feet cotton. 1941 Cotton 310 lbs. Rows on contour. 1931-44. Cane 6 tons 43.8 0.7 1.6 1942 Cotton 220 lbs. Sudan 3 tons 36.1 1.1 0.7 1943 Cotton 431 lbs. Oats Oats 7 bu. 24.6 0.1 1944 Cotton Cane 32.7 5.7 6.4 12.17-year average . . . . . . . . . . . . . . . . . . . . .. 34.5 0.9 1.1 1945 Cotton 228 lbs. 37.2 4.2 6.1 1946 Oats 39 bu. 45.8 0.2 0.1 Since 1944. crop rotation cotton. oats. alfalfa. 1947 Alfalfa 2 tons 27.2 0.2 0.4 Rows down slope or flat. 1948 Cotton 172 lbs. 19.0 1.1 1.3 1949 Oats 79 bu. 32.3 0.1 0.0 5-year average . . . . . . . . . , . . . . . . . . . . . . . . . . 32.3 1.2 1.6 Crop rotation corn. oats (E). oats (E). 1950 Oats (E) 22.4 0.1 0.0 1951 Corn 45 bu. 27.7 0.4 0.3 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 25.1 0.2 0.2 1933 Cotton (3) Vetch Cane (3) 25.2 1.2 0.7 1934 Cotton 176 lbs. Vetch Sudan (3) 30.1 0.3 0.5 1935 Cotton 164 lbs. Vetch Sudan (3) 45.3 5.2 2.5 1936 Cotton 160 lbs. Vetch Sudan (3) 39.0 2.3 0.9 1937 Cotton 327 lbs. Area 0.0505 acre. 17 by 129.5 feet. Vetch Sudan 4 tons 29.2 1.0 0.6 Land slope. 2 percent. 1938 Cotton 292 lbs. 17 Soil. Houston Black clay. Oats Oats 78 bu. 27.6 0.9 0.3 Cropping practice. strip-cropped beginning 1939 Cotton 266 lbs. at bottom of plot. Cane 1 ton 24.4 0.4 0.2 30 feet resistant crop. 99.5 feet cotton. 1940 Cotton 333 lbs. Rows on contour. 1931-44. Sudan 2 tons 39.9 0.6 0.4 1941 Cotton 303 lbs. Oats Oats 23 bu. 43.4 1.3 0.4 1942 Cotton 203 lbs. Cane 4 tons 37.2 2.9 1 7 1943 Cotton 478 lbs. Sudan 1 ton 24.2 0.1 0.1 1944 (1/2 year) Cotton Oats 32.8 5.0 2.5 lll/z-year average . . . . . . . . . . . . . . . . .~ . . . . . . 34.6 1.8 0.9 1945 Oats (H) 42 bu. 37.9 4.1 1.2 1946 Oats (H) 42 bu. 45.0 0.1 0.1 Since 1944. crop rotation continuous 1947 Oats (H) 27 bu. 28.4 0.4 0.1 oats (Hubam). Rows flat. 1948 Oats (H) 5bu. 19.6 0.4 0.1 1949 Oats (H) 69 bu. 32.8 1.1 0.5 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.7 1.2 0.4 46 1,7. Annual summary oi rainiall. runoft and soil loss for all areas under measurement at the Blackland Experiment ' Station. Temple. Texas. 1931-51 (Continued) Soil loss Yield oi Depth Soil per acre Plot or watershed Winter Crop crop Rain- o1 loss per inch of characteristics and treatments Year cover harvested per acre tall runotl acre runott _‘ Bu. or lbs. — -—- Inches — — — — — Tons — — — . Crop rotation corn. oats (E). 1950 Oats (E) 1-3 0-7 0-4 U-s i 1951 Corn 30 bu. 27.5 0.6 0.4 0.6 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 24.4 0.7 0.4 0.6 1933 Grass None None 25.2 (1) (2) 1934 do do do 30.1 (l) (2) 1935 do do do 45.3 1.3 0.4 0.3 Area 0.0286 acre. 9 by 138.35 ieet. 1936 do do do 39.1 (1) (2) Land slope. 2 percent. 1937 do do do 29.2 (1) (2) Soil. Houston Black clay. 1938 do do do 27.6 0.2 0.0 0.1 Cropping practice. continuous 1939 do do do 24.4 ( 1) (2) Bermuclagrass. clipped. 1940 do do do 39.9 (1) (2) 1941 do do do 43.4 2.2 0.3 0.1 1942 do do do 37.2 0.2 0.1 0.3 1943 do do do 24.2 (1) (2) 1944 do do do 50.2 1.3 0.1 0.1 1945 do do do 37.9 1.6 0.2 0.1 1946 do do do 45.0 0.3 0.2 0.6 1947 do do do 28.4 (1) (2) 1948 do do do 19.6 0.2 0.1 0.3 1949 do do do 32.8 0.3 0.0 0.1 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.7 0.5 0.1 0.2 1950 do do do 21.3 (1) (2) 1951 do do do 27.5 (1) (2) 2-year average . . . . . . . . . . . . . . . . _ . . . . . . .. 24.4 0 0 19-year average . . . . . . . . . . . . . . . . . . . . . . . . . 33.1 0 4 0.1 0.2 1933 Cotton No rec. 25.2 1.5 2.8 1.9 _ 1934 Corn 22 bu. 30.1 2.6 7.4 2.8 J 1935 Oats Oats 42 bu. 45.3 1.1 0.8 0.7 c Area 0.0286 acre, 9 by 138.35 feet. 1936 Cotton 413 lbs 39.0 6.2 17.2 2.8 ' Land slope. 2 percent. 1937 Corn 37 bu. 29.2 0.8 1.1 1.3 f. Soil. Houston Black clay. 1938 Oats Oats 71 27.6 0.1 0.1 0.6 ‘ Cropping practice. 3-year rotation 1939 Cotton 230 lbs 24.4 1.4 2.2 1.5 _ cotton. corn. oats. 1940 Corn 34 bu. 39.9 2.9 3.7 1.3 Rows down slope. 1941 Oats Oats 46 bu. 43.4 0.9 0.4 0.4 I 1942 Cotton 236 lbs 37.2 4.8 12.7 2.6 ~" 1943 Corn 28 bu. 24.2 1.0 1.5 1.5 1944 Oats Oats (1/2 yr.) 32.8 4.1 1.4 0.3 lll/z-year average . . . . . . . . . . . . . . . . . . . . . . . 34.6 2.4 4.4 1.9 . 1945 Oats 24 bu. 37.9 2.9 0.9 0.3 I; Crop rotation continuous oats. 1946 Oats 38 45.0 0.4 0.2 0.6 '~ Rows tlat. 1947 Oats 25 28.4 0.1 0.1 0.4 1948 Oats 41 19.6 1.0 0.7 0.7 1949 Oats 45 32.8 1.0 0.5 0.5 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.7 1.1 0.5 0.4 Crop rotation corn. oats (E). oats (E). 1950 Corn 21.3 0.7 0.4 0.6 1951 Oats (E) 27.5 0.5 0.3 0.5 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 24.4 0.6 0.3 0.5 1933 Corn 27 bu. 25.2 2.6 2.9 1.1 1934 Oats Oats 28 bu. 30.1 0.9 1.2 1.3 1935 Cotton 735 lbs 45.3 6.8 11.5 1.7 Area 0.0286 acre. 9 by 138.35 feet. 1936 Corn 49 bu. 39.0 5.7 13.6 2.4 i Land slope. 2 percent. 1937 Oats Oats 50 29.2 0.2 0.4 2.1 , Soil. Houston Black clay. 1938 Cotton 289 lbs. 27.6 3.4 9.0 2.7 "; Cropping practice. 3-year rotation 1939 Corn 38 bu. 24.4 1.0 1.1 1.1 7 cotton. corn. oats. 1940 Oats Oats 20 39.9 4.0 2.4 0.6 » Rows down slope. 1941 Cotton 301 lbs. 43.4 6.0 10.0 1.7 " 1942 Corn 31 bu. 37.2 4.8 11.2 2.3 1943 Oats Oats 39 24.2 0.1 0.2 1.4 1944 (1/2 year Cotton 32.8 10.0 24.8 2.5 lll/z-year average . . . . . . . . . . . . . . . . . . . . . . 34.6 4.0 7.7 1.9 1945 Corn 26 bu 37.9 3.9 3.6 0.9 Cro ing rotation continuous corn with 1946 " Corn 36 45.0 2.8 3.5 1.3 ,_ u am clover winter green manure. 1947 Corn 26 28.4 0.9 0.6 0.7 . Rows down slope or flat. 1948 Corn 24 19.6 1.1 1.1 1.0 ' 1949 Corn 37 32.8 2.6 3.7 1.4 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . 32.7 2.3 2.5 1.1 1950 Corn 21.3 0.4 0.2 0.6 ~ i Crop rotation corn. oats (E). 1951 Oats (E) 27.5 0.5 0.4 0.7 1952 Corn 32 bu. 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . 24.4 0.5 0.3 0.6 1933 Oats Oats 16 bu. 25.2 1.7 2.2 1.3 1934 Cotton 254 lbs. 30.1 3.9 12.3 3.1 1935 Corn 43 bu. 45.3 9.1 17.0 1.9 Area 0.0286 acre. 9 by 138.35 feet. 1936 Oats Oats 40 39.0 2.0 1.1 0.6 Land slope. 2 percent. 1937 Cotton 474 lbs. 29.2 0.3 0.4 1.2 ; Soil. Houston Black clay. 1938 Corn 49 bu. 27.6 2.5 6.4 2.5 i Cropping practice. 3-year rotation 1939 Oats Oats 54 24.4 ( 1) (2) cotton. corn. oats. 1940 Cotton 234 lbs. 39.9 4.3 3.8 0.9 Rows down slope. 1941 Corn 36 bu. 43.4 5.5 11.7 2.1 1942 Oats 37 37.2 0.1 0.2 1.4 1943 Cotton 378 lbs. 24.2 1.2 2.1 1.7 1944 (1/2 year) Corn 32.8 8.7 18.0 2.1 lll/z-year average . . . . . . . . . . . . . . . . . . . . . . 34.6 3.4 6.5 1.9 1945 Cotton 342 lbs 37.9 4.9 7.6 1.5 Since 1947. crop rotation continuous with 1946 Cotton 06 45.0 4.1 6.2 1.5 ubam clover for winter green manure. 1947 Cotton 237 28.4 2.6 5.4 2.1 Rows flat. 1948 Cotton 157 19.6 2.1 3.0 1.4 1949 Cotton 376 32.8 4.5 9.8 2.2 S-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.7 3.6 6.4 1.8 ah Q Yield of Depth Soil Plot or Plot or watershed Winter Crop crop Hain- o loss per watershed characteristics and treatments Year cover harvested per acre fall runoff acre _ ‘ ' Bu. or lbs. - — Inches — — - — — Tons " Crop rotation. corn. oats (E). oats (E). 1950 Oats (E) 21.3 0.4 0.2 1951 Corn 44 bu. 27.5 0.8 0.4 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 24.4 0.6 0.3 1933 Corn 26 bu 25 2 2.9 5.1 1934 do 0 l 3.1 6.1 1935 do 93 45.3 6.2 12.4 Area 0.0286 acre. 9 by 138.35 feet. 1936 do 39 39.0 6.5 18.9 Land slope. 2 percent. 1937 do 35 29.2 0.5 0.9 22 Soil. Houston Black clay. 1938 do 34 27.6 2.6 7.4 Cropping practice continuous corn. ‘ 1939 do 29 24.4 1.0 1.4 Rows down slope. 1940 do 31 39.9 4.5 4.9 1941 do 24 43.4 5.5 13.5 1942 do 29 37 2 7.3 14.1 1943 do 29 24 2 1.5 3.8 1944 do 18 50.2 9.4 22.4 Since 1947. rows flat. 1945 do 22 37.9 4.8 11.3 1946 do 23 45.0 6.5 10.8 1947 do 27 28 4 2.8 4.5 1948 do 14 19 6 2.1 3.1 1949 do 21 32 8 4.2 8.8 5-year average . . . . . . . . . . . . . . . . 21 bu 32 7 4.1 7.7 8-year average . . . . . . . . . . . . . . . . 23 34.4 9.8 17-year average (1933 to 1949) 34.1 4.2 8.8 1950 Oats (E) 21.3 0.7 0.4 Crop rotation corn. oats (E). oats (E). 1951 Oats (E) 27.5 0.2 0.1 1952 Corn 31 bu. 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . 24.4 0.5 0.3 Area. 1.5 acres. 151 by 432 feet. 1939 Cotton 787 lbs. 22.8 0.7 0.9 Land slope. 2.31 percent. 1940 Oats 23 bu. 40.5 4.4 3.0 P-l Soil. 100% Houston Black clay. 1941 Corn 39 41.3 5.1 5.9 Cropping practice 3-year rotation cotton. oats. corn. 1942 Cotton 494 lbs. 36.3 3.3 2.7 Guide lines 108 feet apart. 1943 Oats 31 bu. 25.1 0.5 0.2 Rows on contour. 1944 Corn 14 48.8 4.6 11.7 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 35.8 3.1 4.1 1945 Oats 21 bu. 37.8 4.0 0.9 Crop rotation oats. corn. Hubam. 1946 Corn 31 43.3 2.7 1.8 Conventional plowing. 1947 Hubam 380 lbs. 26.3 0.7 0.2 1948 Oats 19.8 1.0 1.5 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . 31.8 2.1 1.1 Crop rotation cotton. oats (clover). 1949 Cotton 33.1 2.2 4.0 Residue turned under. 1959 0015 (c) 21-7 U-Z 0-1 1951 Cotton 26.6 0.8 2.2 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.1 1.1 2.1 1939 Corn 35 bu. Oats Oats 42 Area 1.5 acres. 151 by 432 feet. Cotton 612 lbs. 22.8 0.0 0.0 Land slope. 2.31 percent. 1940 do 572 P-2 Soil. 100% Houston Black clay. Corn 34 bu. Cropping practice 3-year rotation Oats Oats 19 40.5 3.7 1.2 cotton. oats. corn. 1941 do 33 Strip-cropped 36-foot strips. - COttOn 554 lbs. Guide lines 108 feet apart. Corn 36 bu. 41.3 3.7 2.1 Rows on contour, 1942 Cotton 542 lbs. Corn 21 bu. Oats 20 36.3 2.4 1 9 1943 Cotton 412 lbs. Corn 22 bu. Oats 31 25.1 0.3 0 2 1944 Cotton 256 lbs. Corn ll bu. Oats 25 48.8 3.7 4.6 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 35.8 2.3 1.7 1945 Corn 23 bu. 37.8 3.8 4.3 Crop rotation oats. corn. Hubam. 1946 Hubam 355 lbs. 43.3 3.7 1.6 Residue on surface. 1947 Oats 22 bu. 26.3 1.3 0.4 1948 Corn 19.8 0.4 0.6 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 31.8 2.3 1.7 Crop rotation cotton. oats (clover). oats 1949 » Cotton ‘33.1 0.8 1.7 (clover). 1950 0615 (C) 21.7 0.1 0.1 Residue removed. 1951 Cotton 26.6 0.7 0.9 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.1 0.5 0.9 1939 Oats Oats 49 bu. Cotton 804 lbs Corn 36 bu. 22.8 0.1 0 l 1940 do 32 Area 1.5 acres. 151 by 432 feet. Oats Oats 40 Land slope. 2.78 percent. Cotton 409 lbs. 40.5 3.3 1.5 P-3 Soil. 77% Houston Black clay. 23% Austin clay. 1941 do 427 Cropping practice. 3-year rotation Corn 28 bu cotton. oats. corn. Oats 57 41.3 4.0 1.6 Strip-cropped. 36-foot strips. 1942 Cotton 522 lbs. Guide lines 108 feet apart. Corn 29 bu. Rows on contour. Oats 25 36.3 2.9 1.5 1943 Cotton 502 lbs. Corn 25 bu Oats 25 25.1 0 6 0 3 1944 Cotton 272 lbs. Corn 16 bu. Oats 20 48.8 4.3 2.9 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 35.8 2.5 1.3 48 Table 17. Annual summary of rainfall. runoff and soil loss for all areas under measurement at the Blackland E - i Station. Temple. Texas, 1931-51 (Continued) p. Annual summary of rainfall. runoff and soil loss for all areas ‘under measurement at the Blackland Experiment Station. Temple, Texas, 1931-51 (Continued) .3 Soil loss .‘ Yield of Depth Soil per acre Plot or watershed Winter Crop crop Rain- of loss per inch of _ characteristics and treatments Year cover harvested per acre fall runoff acre runoft Bu. or lbs. -— — Inches — — —- — — Tons —— — —— 1945 Hubam 130 lbs. 37.8 4.5 2.4 0.5 t Crop rotation Hubam. oats. corn. 1946 Oats 28 bu. 43.3 1.2 0.1 0.1 Residue on surface. 1947 Corn 3 26.3 1.5 1.0 0.7 1948 Hubam 19.8 0.5 0.3 0.6 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 31.8 1.9 1.0 0.5 Crop rotation cotton. oats (clover). 1949 Cotton 33.1 3.0 4.3 1.4 Residue on top. 1950 Oats (C) 21.7 0.2 0.1 0.6 1951 Cotton 26.6 1.3 2.5 1.9 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.1 1.5 2.3 1.5 Area. 1.5 acres. 151 by 432 feet. 1939 Corn 29 bu. 22.8 0.7 2.5 3.7 Land slope. 3.01 percent. 1940 Cotton 561 lbs. 40.5 4.6 13.6 3.0 Soil. 44% Houston Black clay. 56% Austin clay. 1941 Oats Oats 43 bu. 41.3 4.4 4.6 1.1 Cropping practice.,3-year rotation cotton. 1942 Corn 25 36.3 3.4 11.8 3.4 1 . oats. corn. 1943 Cotton 536 lbs. 25.1 0.7 2.4 3.5 " Guide lines 108 feet apart. 1944 Oats 28 bu. 48.8 3.7 2.2 0.6 ‘ ROWS 0n Cvntwr- 6-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 35.8 2.9 6.2 2.1 1945 Hu m 1 1 . . . . . Crop rotation Hubam. oats. corn. 1946 Call’: Conventional plowing. 1947 Corn 7 bu. 26.3 1.4 3.8 2.8 1948 Hubam 19.8 0.6 0.7 1.2 11-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 31.8 1.9 2.7 1.4 Crop rotation cotton. oats (clover). 1949 Oats (C) 33.1 0.2 0.1 0.6 oats (clover). 1950 Cotton 21.7 0.5 0.6 1.4 Residue removed. 1951 Oats (C) 26.6 0.4 0.2 0.4 e 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.1 0.3 0.3 0.9 1939 Cotton 463 lbs. Corn 24 bu. Oats Oats 30 22.8 0 1 0.1 0 5 1940 do 31 _ Cotton 549 lbs ‘ . Corn 25 u 40.5 4 4 4 1 0 9 Area. 1.5 acres. 151 by 432 feet. 1941 do 24 Land slope. 3.01 percent. Oats 33 i‘ Soil. 56% Houston Black clay. 44% Austin c1a_y. Cotton 656 lbs. 41.3 3 5 3.4 1 0 ‘ Cropping practice. 3-year rotation 1942 do 374 cotton. oats. corn. Corn 19 bu. l Strip-cropped. 36-foot strips. Oats 5 36.3 4 0 2.1 0 5 1943 Cotton 288 lbs. Corn 18 bu Oats 14 25.1 0 7 1 1 1 5 1944 Cotton 182 lbs. Corn 10 bu. Oats 21 bu 48.8 4.3 7.1 1.6 6-year average . . . . . . . . . . . . . . . , . . . . . . . . . . 35.8 2.8 3.0 1.0 1945 Oats 20 bu 37.8 5.1 2.0 0.4 Crop rotation oats. corn. Hubam. 1946 Corn 21 43.3 3.7 5.0 1.4 Residue on surface. 1947 Hubam 347 lbs. 26.3 2.2 1.2 0.6 1948 Oats 19.8 0.6 0.7 1.3 4-year average . . . . . . . . . . . . . . . . . . . . . . 31.8 2.9 2.2 0.8 Crop rotation cotton. oats (clover). 1949 Oats (C) 33.1 0.0 0.0 1.0 Residue turned under. 1950 Cotton 21.7 0.2 0.3 1.2 1951 Oats (C) 26.6 0.0 0.1 2.2 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.1 0.1 0.1 1.3 g Area. 1.5 acres. 151 by 432 feet. 1939 Oats Oats 41 bu. 22.8 0.0 0.0 0.5 1 Land slope. 3.01 percent. 1940 Corn 26 40.5 6.7 10.0 1.5 ' Soil. 90% Houston Black clay. 10% Austin clay. 1941 Cotton 470 lbs. 41.3 5.2 7.4 1.4 Cropping practice. 3-year rotation 1942 Oats Oats 8 bu. 36.3 3.9 1.4 0.4 cotton. oats. corn. 1943 Corn 21 25.1 0.7 0.9 1.2 Guide lines 108 feet apart. 1944 Cotton 271 lbs. 48.8 5.2 20.0 4.0 Rows on contour. 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . 35.8 3.7 6.8 1.9 1945 Corn 16 bu. 37.8 5.3 10.1 1.9 Crop rotation corn. Hubam. oats. 1946 Hubam 267 lbs. 43.3 2.0 1.0 0.5 Conventional plowing. 1947 Oats 27 bu. 26.3 1.4 0.8 0.6 1948 Corn 19.8 0.2 2.7 14.3 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 31.8 2.2 3.7 1.7 ' Crop rotation cotton. oats (clover). 1949 Oats (C) 33.1 0.0 0.0 0.9 Residue on top. 1950 Cotton 21.7 0.2 0.1 0.6 1951 Oats (C) 26.6 0.0 0.1 2.2 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.1 0.1 0.1 0.9 Area. 1.5 acres. 151 by 432 feet. 1939 Oats 30 bu. 23.0 (1) (2) Land slope. 2.31 percent. 1940 Corn 40 40.6 0.8 0.7 1.0 Soil. 100% Houston Black clay. 1941 Cotton 948 lbs. 41.9 1.7 2.5 1.4 Cropping practice. 3-year rotation 1942 Oats Oats 7 bu. 36.4 1.2 0.5 0.4 cotton. oats. corn. 1943 Corn 22 bu. 25.1 0.3 0.2 0.7 Guide line 108 feet apart. 1944 Cotton 343 lbs. 49.4 3.3 8.8 2.7 Rows on contour. 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 36.0 1.2 2.1 1.7 1945 Oats 29 bu 38.1 3.3 0.8 0.2 Crop rotation oats. corn. clover. 1946 Corn 3 44.5 3.4 2.8 0.8 Residue on surface. 1947 Hubam 433 lbs. 27.4 0.6 0.7 1.0 Rows on contour. 1948 Oats (C) 19.6 1.2 1.5 1.3 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 2.1 1.4 0.7 Crop rotation cotton. oats (clover). 1949 Cotton 32.7 2.1 5.0 2.4 Residue on top. 1950 Oats (C) 22.0 0.1 0.1 0.8 Rows on contour. 1951 Cotton 27.1 1.3 4.6 3.4 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 1.2 3.2 2.7 49 Table 17. Annual summary of rainfall, runoff and soil loss for all areas under measurement at the Blackland E l Station. Temple, Texas. 1931-51 (Continued) Yield of Depth Soil Plot or Plot or watershed Winter Crop crop Rain- o loss per watershed characteristics and treatments Year cover harvested per acre fall runoff acre Bu. or lbs. — — Inches — — — — —- To ‘ Area, 1.5 acres, 151 by 432 feet. 1939 Corn 33 bu. 23.0 0.0 0.0 ' Land slope, 1.85 percent. 1940 Cotton 687 lbs. 40.6 1.6 0.7 O-2 Soil, 100% Houston Black clay. 1941 Oats Oats 61 bu. 41.9 3.2 0.9 Cropping practice. 3-year rotation 1942 Corn 33 36.4 1.8 1.6 cotton, oats, corn. 1943 Cotton 737 lbs. 25.1 0.0 0.0 Guide rows 108 feet apart. 1944 Oats Oats 44 bu. 49.4 2.7 0.8 Rows on contour. 6-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 36.0 1.6 0.7 1945 Hubam 123 lbs. 38.1 3.1 1.4 Crop rotation Hubam, oats, corn. 1946 Oats 28 bu. 44.5 0.7 0.1 Residue on surface. 1947 Corn 11 27.4 1.9 1.4 Rows on contour. 1948 Hubam 19.6 0.6 0.5 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 1.6 0.9 Crop rotation cotton, oats (clover), oats (c). 1949 Cotton 32.7 2.4 5.0 Residue removed. 1950 Oats (C) 22.0 0.1 0.0 Rows on contour. 1951 Cotton 27.1 0.9 1.8 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.7 1.1 2.3 1939 Oats Oats 28 bu. Cotton 566 lbs. Corn 35 bu. 23.0 0.1 0 1 1940 do 35 Oats Oats 21 Area, 1.5 acres, 151 by 432 feet. Cotton 456 lbs. 40.6 1 1 0.3 Land slope, 2.08 percent. 1941 do 621 O-3 Soil, 100% Houston Black clay. Corn 36 bu. Cropping practice, 3-year rotation Oats Oats 57 ~ 41.9 2 1 0.6 cotton, oats, corn. 1942 Cotton 624 lbs. Strip-cropped 36-foot strips. Corn 33 bu. Guide lines 108 feet apart. Oats Oats 16 36.4 1 1 1 1 Rows on contour. 1943 Cotton 480 lbs. Corn 22 bu. Oats Oats 30 25 1 0.0 0 0 1944 Cotton 412 lbs. Corn 22 bu. . Oats Oats 38 49.4 3.1 1.7 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 36.0 1.2 0.6 1945 Oats 22 bu 38.1 3.0 1.4 » Crop rotation corn, Hubam, oats (clover). 1946 Corn 34 44.5 2.1 2.1 é Conventional plowing. 1947 Hubam 553 lbs. 27.4 0.6 0.2 . 1948 Oats 19.6 0.6 0.5 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 1.6 1.0 Crop rotation cotton, oats (clover). 1949 Cotton 32.7 1.8 2.3 Residue turned under. 1950 Oats (C) 22.0 0.1 0.0 1951 Cotton 27.1 0.9 0.9 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 0.9 1.1 Area, 1.5 acres, 151 by 432 feet. 1939 Cotton 795 lbs. 23.0 0.3 0.3 Land slope, 2.08 percent. 1940 Oats Oats 23 bu. 40.6 4.2 1.4 O-4 Soil, 100% Houston Black clay. 1941 Corn 40 41.9 3.5 3.0 Cropping practice, 3-year rotation 1942 Cotton 619 lbs. 36.4 2.4 2.1 cotton, oats, corn. 1943 Oats 31 bu. 25.1 0.5 0.1 Guide lines 108 feet apart. 1944 Corn 19 49.4 4.2 5.7 Rows on contour. 6-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 36.0 2.5 2.1 1945 Corn 26 bu. 38.1 3.5 2.2 Crop rotation corn, Hubam, oats. 1946 Hubam 275 lbs. 44.5 1.9 0.6 ‘ Conventional plowing. 1947 Oats (H) 39 bu. 27.4 1.3 0.6 1948 Corn 19.6 0.2 0.2 _ 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 1.7 0.9 Crop rotation cotton, oats (clover). 1949 Oats (C) 32.7 0.0 0.0 Residue on top. 195'! Cotton 22.0 0.1 0.1 1951 Oats (C) 27.1 0.0 0.0 .1 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 0.0 0.0 5 1939 Cotton 558 lbs. Corn 33 bu. Oats Oats 29 23.0 0.1 0.2 1940 do 27 Cotton 542 lbs. Area, 1.5 acres, 151 by 432 feet. Corn 34 bu. 40.6 1.3 0.9 Land slope, 2.31 percent. 1941 do 28 O-5 Soil, 100% Houston Black clay. Oats Oats _ 63 , Cropping practice, 3-year rotation Cotton 629 lbs. 41.9 2.3 1.0 _, cotton, oats, corn. 1942 do 804 ~ Strip-cropped, 36-foot strips. Corn 28 bu. , Guide lines 108 feet apart. Oats Oats 15 36.4 1.5 17 , Rows on contour. 1943 Cotton 521 lbs. 1 Corn 17 bu. f' Oats Oats 42 25.1 0.2 0 1 f 1944 Cotton 266 lbs. _ Corn 15 bu. ; Oats Oats 28 49.4 3.7 6.5 If G-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 36.0 1.5 1.7 I 1945 Corn 17 bu. 38.1 3.4 4.8 Crop rotation corn, Hubam, oats (Hubam). 1946 Hubam 233 lbs. 44.5 4.4 3.1 Residue on surface. 1947 Oats (H) 22 bu. 27.4 1.9 0.9 1948 Corn 19.6 0.5 1.9 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 2.6 2.7 Crop rotation cotton, oats (clover). 1949 Oats (C) 32.7 0.0 0.0 Residue turned un er. 1950 Cotton 22.0 0.1 0.1 1951 Oats (C) 27.1 0.0 0.0 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 0.1 0.1 50 ‘L. .* Annual summary of rainfall, runoff and soil loss for all areas under measurement at the Blackland Experiment Station. Temple, Texas, 193l-51 (Continued) Soil loss Yield of Depth Soil per acre Plot or watershed Winter Crop crop Rain- of loss per inch of characteristics and treatments Year cover harvested per acre fall runoff acre runoff Bu. or lbs. — —1nches — — — — —- Tons — — — 1939 Cotton 596 lbs. Corn 33 bu. Oats 35 23.0 0.0 (8) 1940 do 28 Cotton 639 lbs. Area. 1.5 acres. 151 by 432 feet. Corn 37 bu. 40.6 3.5 0.8 0.2 Land slope. 1.39 percent. 1941 do 34 Soil. 100% Houston Black clay. Oats 44 Cropping practice. 3-year rotation Cotton 829 lbs 41.9 3.9 1.2 0.3 cotton. oats. corn. 1942 do 66 Strip-cropped. 36-foot strips. Corn 23 bu. Guide lines 108 feet apart. Oats 22 36.4 2.1 0.9 0.5 Bows on contour. 1943 Cotton 737 lbs Corn 27 bu. Oats 22 25 1 0.0 0 0 1 2 1944 fatten 252 lbs Corn 10 bu. Oats 27 49.4 3.9 3.3 0.8 6-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 36.0 2.2 1.0 0.5 1945 Hubam 180 lbs. 38.1 4.2 1.6 0.4 Crop rotation Hubam. oats. corn. 1946 Oats 35 bu. 44.5 0.5 0.1 0.1 Conventional plowing. 1947 Corn 16 27.4 1.3 0.9 0.7 1948 Hubam 19.6 0.1 0.1 0.7 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . 32.4 1.6 0.7 0.4 Crop rotation cotton. oats (clover). oats 1949 Oats (C) 32.7 0.0 0.0 (clover). 1950 Cotton 22.0 0.0 0.0 1.2 Residue removed. 1951 Oats (C) 27.1 0.0 0.0 3-year average . . . . . . . . . . . . . . . . . . . . . . . . . 27.3 0.0 0.0 1.3 1931 Corn 15 bu. 24.7 0.3 0.1 0.3 1932 Cotton 227 lbs 33.1 1.0 1.4 1.4 J 1933 Oats ats 6 bu. 25.3 2.2 1.8 0.8 C-5 1934 Cotton 139 lbs 29.8 1.2 2.6 2.1 : Area. 1.044 acres. 1935 Corn 17 bu. 45.9 7.6 6.3 0.8 t Length. 850 feet. 1936 Cotton 321 lbs 40.5 8.5 4.6 0.5 Vertical interval. 3 feet. 1937 Oats Oats 35 bu. 29.5 1.8 0.6 0.3 Grade. 3 inches per 100 feet. 1938 Cotton 35'] lbs 28.9 3.5 1.9 0.5 Land slope. 5.4 percent. 1939 Corn 20 bu. 22.2 0.1 0.0 0.3 Soil. 40% Houston Black clay. 1940 Cotton 408 lbs 40.9 7.8" 3.1 0.4 60% Austin clay. 1941 Oats Oats 26 bu. 40.6 6.1 1.4 0.2 Cropping practice cotton. corn. cotton. oats. 1942 Cotton 494 lbs 35.9 4.1 2.1 0.5 1943 Corn 17 bu. 25.3 1.0 0.6 0.7 1944 Cotton 258 lbs 47.9 11.2 10.9 1.0 1945 Oats Oats 20 bu. 37.8 7.2 1.1 0.1 1946 otton 154 lbs 42.5 6.0 2.4 0.4 16-year average . . . . . . . . . . . . . . . . . . . . . . .. 34.4 4.3 2.5 0,6 1947 Hubam 25.0 4.3 2.5 0.6 1948 16.9 4.2 2.4 0.6 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 20.9 4.3 2.5 0.6 1931 Corn 19 bu. 24.7 (4) 0.0 1932 Cotton 259 lbs. 33.2 1.5 0.7 0.0 1933 Oats Oats 6 bu. 25.3 2.3 1.9 0.8 1934 Cotton 128 lbs 29.7 1.4 2.9 2.1 .C-6 1935 Corn 21 bu. 45.9 7.7 7.7 1.0 Area. 1.473 acres. 1936 Cotton 383 lbs 40.5 8.6 5.6 0.7 Length. 844 feet. 1937 Oats Oats 37 bu 29.5 1.1 1.2 1.1 Vertical interval. 4 feet. 1938 Cotton 274 lbs 28.9 3.4 3.7 1.1 Grade. 3 inches per 100 feet. 1939 Corn 27 bu 22.2 0.1 0.0 0.3 Land slope. 5.4 percent. 1940 Cotton 395 lbs 40.9 7.1 3.5 0.5 Soil. 30% Houston Black clay. 1941 Oats Oats 35 bu 40.6 4.5 1.0 0.2 70% Austin clay. 1942 Cotton 339 lbs 35.9 2.8 1.7 0.6 1943 Corn 21 bu. 25.3 0.6 1.1 1.8 1944 Cotton 237 lbs 47.9 10.2 11.4 1.1 1945 Oats Oats 19 bu. 37.8 7.2 1.3 0.2 1946 Cotton 154 lbs. 42.5 4.7 2.7 0.6 l6-year average . . . . . . . . . . . . . . . . . . . . . . . . . 34.4 3.9 2.9 0.7 1947 Hubam 25.0 3.7 2.0 0.5 1948 Hubam 16.9 1.6 0.7 0.4 2-year average . . . _ . . . . . . . . . . . . . . . . . . . _ . . 20.9 2.6 1.3 0.5 1931 Corn 18 bu. 24.7 0.1 0.2 1.5 _ 1932 Cotton 468 lbs. 33.3 1.8 2.0 1.1 1933 Oats Oats 6 bu. 25.3 1.9 2.3 1.2 'C-7 1934 Cotton 155 lbs. 29.7 1.4 3.0 2.2 sI Area. 1.831 acres. 1935 Corn 21 bu. 46.0 9.7 11.5 1.2 ‘ Length. 828 feet. 1936 Cotton 320 lbs. 40.6 9.1 10.0 1.1 Vertical interval. 5 feet. 1937 Oats Oats 42 bu. 29.5 0.7 1.4 2.1 Grade. 3 inches per 100 feet. 1938 Cotton 323 lbs. 28.8 5.3 6.3 1.2 i‘ Land slope. 5.4 percent. 1939 Corn 28 bu. 22.2 0.2 0.1 0.3 ‘ Soil. 41% Houston Black clay. 1940 Cotton 381 lbs. 40.9 5.9 4.3 0.7 ' 9% Austin clay. 1941 Oats Oats 38 bu 40.6 4.1 1.3 0.3 Cropping practice cotton. corn. cotton. oats. 1942 Cotton 399 lbs 35.9 3.8 3.6 1.0 1943 Corn 19 b 25.3 0.9 1.7 2.0 1944 Cotton 279 lbs 47.9 10.1 17.9 1.8 1945 Oats Oats 23 bu. 37.8 5.8 1.2 0.2 1946 Cotton 154 lbs. 42.5 4.0 2.8 0.7 l6-year average . . . . . . . . . . . . . . . . . . . . . . . . . 34.4 4.1 4.4 1.1 1947 Hubam 25.0 3.2 2.2 0.7 1948 Oats 16.9 0.9 0.2 0.2 2-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 20.9 2.1 1.2 0.6 51 Table 17. Annual summary of rainfall, runoff and soil loss for all areas under measurement at the Blackland t; Station. Temple, Texas. 1931-51 (Continued) Yield of Depth Soil Plot or Plot or watershed Winter Crop crop Rain- of loss per watershed characteristics and treatments Year cover harvested per acre fall runoff acre Bu. or lbs. — — Inches — — — — Tons Terrace C-13 1932 Cotton 153 lbs. 33.6 2.1 1.0 Area. 3.937 acres. 1933 Oats Oats 6 b . 25.5 2.3 1.9 Length. 1.930 feet. 1934 Cotton 176 lbs 29.6 2.6 2.5 Vertical interval. 3.9 feet. 1935 Corn 18 bu. 46.4 9.1 6.5 Grade. 0-3 inches per 100 feet. variable. 1936 Cotton 404 lbs 40.8 8.8 2.4 Land slope. 4.4 percent. 1937 Oats Oats 34 bu. 29.2 1.6 0.5 Soil. 51% Houston Black clay. 1938 Cotton 254 lbs 28.3 3.0 1.8 49% Austin clay. 1939 Corn 28 bu. 22.7 0.0 0.0 Cropping practice cotton. corn. cotton. oats. 8-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 32.0 3.7 2.1 1940 Oats Oats 22 bu. Cotton 403 lbs 42.3 6.5 1.1 1941 Oats Oats 11 bu. Cropping practice cotton. corn rotated. Corn 27 40.9 6.4 1.3 Oat strip permanent. 1942 Oats Oats 9 Cotton 589 lbs 36.8 3.3 0.4 1943 Oats Oats 12 bu. Corn 21 25.2 0.2 0.0 1944 Oats Oats 5 bu. Cotton 295 lbs 48.5 9.3 4.0 5-vear average . . . . . . . . . . . . . . . . . . . . . . . . . . 38.7 5.1 1.4 1945 Corn 14 bu. 38.3 7.2 0.8 Cropping practice corn. clover. cotton. 1946 Clover 267 lbs 41.8 1.1 0.1 oat-clover. 1947 Cotton 374 25.7 1.6 0.6 1948 Oats-Clover 16.9 0.5 0.2 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 30.7 2.6 0.4 Terrace C-14 1932 Cotton 198 lbs. 33.6 2.0 1.5 Area. 4.047 acres. 1933 Oats Oats 9 bu. 25.5 2.5 2.1 Length. 1.875 feet. 1934 Cotton 211 lbs. 29.6 0.7 0.6 Vertical interval. 3.4 feet. 1935 Corn 19 bu. 46.4 11.3‘ 9.8 Grade. 3 inches per 100 feet. 1936 Cotton 232 lbs. 40.8 7.1 4.7 Land slope. 4.1 percent. 1937 Oats Oats 32 bu. 29.2 1.2 0.7 Soil. 64% Houston Black clay. 1938 otton 270 lbs. 28.3 4.9 2.8 36% Austin clay. 1939 Corn 29 bu. 22.7 0.1 0.0 Cropping practice cotton. corn. cotton. oats. 8-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 32.0 3.7 2.8 1940 Cotton 282 lbs. 42.3 8.2 2.2 1941 Corn 21 u. 40.9 9.7 3.0 Cropping practice cotton. corn. 1942 Cotton 410 lbs. 36.8 3.7 0.9 1943 Corn 18 bu. 25.2 0.3 0.1 1944 Cotton 242 lbs. 48.5 - 13.3 9.7 S-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 38.7 7.0 3.2 1945 Cotton 413 lbs. 38.3 8.7 2.3 Cropping practice cotton. oats. corn. clover. 1946 Oats Oats 33 bu. 41.8 3.6 0.8 1947 Corn 25.7 2.6 1.0 1948 Clover 16.9 0.0 0.0 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 30.7 3.7 1.0 Terrace C-15 1932 Cotton 165 lbs. 33.6 1.4 0.8 Area. 3.443 acres. 1933 Oats Oats 9 u. 25.5 2.0 1.5 Length. 1.856 feet. 1934 Cotton 179 lbs. 29.6 1.9 1.9 Vertical interval. 2.8 feet. 1935 Corn 23 bu. 46.4 10.0 7.6 Grade. 4 inches per 1G0 feet. 1936 Cotton 298 lbs 40.8 9.4 5.4 Land slope. 3.6 percent. 1937 Oats Oats 38 bu. 29.2 2.0 0.6 Soil. 85% Houston Black clay. 1938 Cotton 362 lbs 28.3 4.5 2.4 5% Austin clay. 1939 Corn 35 bu 22.7 0.1 0.0 Cropping practice cotton. corn. cotton. oats. 8-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 32.0 3.9 2.5 1940 Cotton 359 lbs 42.3 7.6 2.2 1941 Corn 25 bu 40.9 9.2 2.7 Cropping practice cotton. corn. 1942 Cotton 567 lbs 36.8 3.2 0.6 1943 Corn 20 bu. 25.2 0.3 0.1 1944 Cotton 285 lbs. 48.5 12.0 7.8 5-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 38.7 6.4 2.7 1945 Cotton 413 lbs. 38.3 8.7 2.3 Cropping practice cotton. oats. corn. clover. 1946 Oats 33 bu. 41.8 3.6 0.8 1947 Corn 25.7 2.6 1.0 1948 Clover 16.9 0.0 0.0 4-year average . . . . . , . . . . . . . . . . . . . . . . . . . 30.7 3.7 1.0 Terrace C-16 1932 Cotton 244 lbs 33.7 1.6 0.2 Area. 3.960 acres. 1933 Oats Oats 12 bu. 25.5 2.0 1.6 Length. 1.870 feet. 1934 Cotton 271 lbs 29.5 1.7 1.7 Vertical interval. 2.8 feet. 1935 Corn 26 bu. 46.5 8.7 6.7 Grade. 5 inches per 100 feet. 1936 Cotton 188 lbs. 40.8 8.6 4.2 Land slope. 3.1 percent. 1937 Oats Oats 39 bu. 29.2 1.6 0.4 Soil. 92% Houston Black clay. 1938 Cotton 355 lbs 28.3 4.5 3.1 8% Austin clay. 1939 Corn 31 bu. 22.7 0.2 0.1 Cropping practice cotton. corn. cotton. oats. 8-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 32.0 3.6 2.2 1940 Oats Oats 28 bu. Cotton 383 lbs 42.3 7.9 0.9 1941 Oats ats 38 bu. Corn 30 40.9 6.4 1.4 Cropping practice cotton. corn rotated. 1942 Oats Oats 22 Permanent oat strip. Cotton 587 lbs. 36.8 2.5 0.2 1943 Oats Oats 22 bu. Corn 18 25.2 0.3 0.1 1944 Oats Oats 14 Cotton 294 lbs 48.5 8.7 2.9 S-year average . . . . . . . . . . . . . . . . . . . . . . . . .. 38.7 5.2 1.1 52 Annual summary of rainfall. runoff and soil loss for all areas under measurement at the Blackland Experiment Station. Temple. Texas. 1931-51 (Continued) Soil loss Yield of Depth Soil per acre I Plot or watershed Winter Crop crop Rairi- of loss per inch of ’ <1 characteristics and treatments Year cover harvested per acre fall runoff acre runoff Bu. or lbs. — — Inches — — — — — Tons — — — 1945 Oats Oats 21 bu. 38.3 6.2 0.6 0.1 1946 Corn 31 41.8 2.2 0.4 0.2 Cropping practice oats. corn. clover. cotton. 1947 Clover 25.7 2.4 0.6 0.2 1948 Cotton 16.9 1.4 0.8 0.6 4-year average . . . . . . . . . . . . . . . . . . . . . . . . . . 30.7 3.0 0.6 0.2 C-17 1932 Cotton 339 lbs. 33.8 1.5 1.6 1.1 z Area. 3.778 acres. 1933 Oats Oats 12 bu. 25.3 1.5 1.0 0.7 l Length. 1.890 feet. 1934 Cotton 352 lbs. 29.6 1.7 1.2 0.7 Vertical interval. 2.9 feet. 1935 Corn 30 bu. 46.2 11.9 6.9 0.6 Grade. 0-5 inches per 100 feet. variable. 1936 Cotton 465 lbs. 40.8 6.7 4.2 0.6 Land slope. 3.2 percent. 1937 Oats Oats 54 bu. 29.3 1.2 0.3 0.3 e- Soil. 96% Houston Black clay. 1938 Cotton 306 lbs. 28.5 3.9 2.4 0.6 4% Austin, clay. 1939 Corn 4U bu. 19.4 0.0 (8) 0.6 Cropping practice cotton. corn. cotton. oats. 7.8-year average . . . . . . . . . . . . . . . . . . . . . . .. 32.4 3.6 2.3 0.6 118. Individual storm data for all storms causing runoff on Plot 3 (continuous corn) shown in comparison with Plot 6 ' (ungrazed Bermudagrass) Water and soil loss _ Intensities _ _ Plot 3 Plot 6 f all rains Rain- S-minute 15-minute 30-mi_nute c°ndm°n _ Depth of Soil loss Depth of Soil loss ’ runoff fall period period period of corn I of soil runoff per acre runoff per acre Inches — — — Inches per hr. — — — Inches Tons Inches Tons 2.55 2.40 1.68 1.14 3"-4" Wet. packed 0.532 1.35 0.042 0.01 0.73 2.52 0.92 0.52 5" Moist. crusted 0.063 0.13 2.23 2.76 1.52 0.96 5"-6" Wet. packed 0.903 1.39 0.05 0.60 5"-6" Wet. packed 0.009 0.01 1.67 1.80 1.60 1.48 8"-10" Loose cult. 0.054 0.06 1.19 4.32 1.84 0.96 8"-10" Wet 0.237 0.54 3.16 3.24 2.64 2.24 12"-14" Moist. packed 2.007 11.29 0.043 T 0.29 0.36 0.24 0.24 12"-14" Moist. packed 1.21 3.12 2.00 1.90 24"-36" Wet 0.551 2.28 0.031 T 1.07 1.08 0.88 0.82 24"-36" Wet 0.178 0.24 0.008 T 1.57 6.00 4.28 2.70 Harvested Moist 0.185 0.19 0.011 0.01 0.62 3.24 2.16 1.22 Harvested Wet. sl. packed 0.237 0.46 0.002 T 0.65 2.64 1.60 0.86 Harvested Wet 0.135 0.29 5.65 3.60 2.68 2.18 Harvested Wet. packed 3.105 3.63 0.004 T 0.52 Harvested Wet. packed 0.160 0.10 0.47 1.68 0.80 0.58 Harvested Moist 0.042 0.03 0.96 0.24 0.24 0.22 Harvested 1y 24.05 8 398 21.99 0 141 0 02 0.55 3.48 2.04 1.10 Not up Dry. loose. flat 2.38 3.84 2.68 2.32 Not up Flat. moist 1.238 2.93 1.51 2.40 1.36 1.08 2"-3" Moist. packed 0.263 0.35 0.001 T 0.44 2.16 1.08 0.56 4"-22" Moist 0.026 0.03 I 1 1.62 1.92 0.96 0.70 2'-5‘ Dry. loose 0.107 0.06 0.002 T 1.12 3.29 3.60 2.88 1.80 6'_ _ Dry. cracked 0.442 0.91 0.006 T ' 0.51 1.92 1.60 1.02 Ripening Moist. flat 0.065 0.15 0.003 T . 1.65 1.08 0.88 0.86 Ripening We_t. flat 0.026 0.02 0.017 T 1.15 1.32 1.24 1.22 Open Moist. flat 0.073 0.04 0.010 T 1.43 2.76 2.12 1.48 Open in beds Wet 0.124 0.14 0.019 0.01 0.78 1.68 1.24 0.88 Open in beds Wet 0.141 0.20 l: 23 2.09 4.08 1.96 0.96 Open in beds Saturated 0.693 1.43 0.013 0.01 1.42 3.60 2.12 1.30 Open in beds Wet 0.309 0.61 0.006 T 0.40 2.16 0.96 0.50 Open in beds Wet 0.059 0.04 0.002 T 1.21 1.80 1.68 1.08 Open in beds Wet 0.446 0.86 0.013 T 3.72 3.00 2.08 1.40 5“- " Dry 0.862 1.48 0.003 T 3.55 6.00 3.60 3.10 5"-7" Wet 1.612 13.26 0.457 0.06 0.87 0.48 0.38 0.36 5"-7" Wet 0.122 0.03 0.003 T 1.38 3.24 2.32 1.60 6"-9" Wet 0.650 0.90 0.007 T 1.68 1.92 1.64 1.20 14"-16" Moist 0.229 0.24 0 005 T 1.02 2.04 0.92 0.66 16"-18" Wet 0.056 0.04 1.02 5.28 3.04 1.72 2‘ Saturated 0.491 0.82 0.001 T 0.92 3.12 1.56 0.90 2: Saturated 0.414 0.52 0.001 T 2.75 2.88 2.80 2.30 3 Wet. loose 1.041 2.52 0.004 T 0.68 5.52 2.60 3'-4‘ Wet. packed 0.450 1.39 0.28 1.68 1.00 3'-4' We_t 0.010 0.02 1.73 2.40 1.64 Open. flat Moist 0.039 0.05 0.008 T 1.58 2.88 1.52 Open. flat S1. wet 0.140 0.18 0.010 T 2.47 1.92 1.84 Open. cloddy Wet 0.017 0.02 ._ 17 303g 7.905 24.75 0.552 0.08 2.63 1.08 0.76 0.54 Open in beds Loose. sl. wet 0.006 T 0.002 T _' 2.97 2.04 1.52 1.12 Open in beds Loose. sl.. wet 0.758 0.76 0.002 T 40.21 1.27 3.84 1.52 0.80 Open in beds Wet. packed 0.136 0.22 0.002 T l a 0.93 1.80 1.32 0.74 Open in beds Saturated 0.245 0.24 ‘ 0.21 1.32 0.48 0.28 Open in beds Saturated 0.096 0.11 0.14 0.48 0.32 0.20 Open in beds Saturated 0.009 0.01 0.42 1.32 0.96 0.68 Planted Moist. loose 0.001 T l pr. 1 1.39 1.44 0.92 0.92 3"-4" Moist. flat 0.021 0.04 ~ 5.70 4.32 2.92 2.78 4"-6" Moist. loose 1.251 2.81 0.704 0.04 0.85 5.40 2.76 1.42 12"-18" Moist. loose 0.258 2.11 0.004 T 0.87 2.04 1.60 1.38 18"-22" Moist. packed 0.233 0.28 1.65 1.56 1.40 1.24 4‘-5‘ oist 0.335 0.21 1.51 3.12 2.16 1.32 5'-6' Wet. packed 0.399 0.36 .30 1.62 3.96 2.32 1.44 Harvested. cut Dry. cracked 0.145 0.25 1.64 1.92 1.46 0.88 Open Wet 0.225 0.08 339 4.118 7.48 0.714 0.04 é- IO 53 Table 18. Individual storm data lor all storrns causing runoli on Plot 3 (continuous com) shown in comparison (ungrazed Bermudagrass) (Continued) Water and soil loss .' Intensities _ _ Plot 3 P - ; Date of all rains Rain- 5-minute 15-minute 30-minute C°nd1h°n Depth ot Soil loss Depth o! » causing runol! tall period period period of corn l of soil runolt per acre runoll " Inches — — — Inches per hr. — — — Inches Tons Inches ‘ 1946 Ian. 4 1.06 5.04 2.80 1.56 Open in beds Moist 0.183 0.15 Ian. 7-8 0.72 0.60 0.44 0.32 Open in beds Wet 0.118 0.01 Ian. 10-11 0.65 0.36 0.28 0.24 Open in beds Saturated 0.172 0.02 Ian. 14-15 1.35 0.60 0.40 0.32 Open in beds Saturated 0.331 0.02 Feb. 9 0.98 3.00 1.12 0.66 Open in beds Wet. packed 0.108 0.11 Feb. 17-18 1.50 3.12 2.00 1.20 Open in beds Wet. packed 0.299 0.43 0.009 Mar. 12-13 2.07 1.08 0.64 0.65 Planted Moist. loose 0.017 0.12 0.019 Mar. 25 0.81 1.68 0.88 0.58 -—- i- T T 0.005 Mar. 26 0.33 1.08 0.56 0.36 Up Moist. packed 0.004 T 0.003 Apr. 22-23 2.93 2.88 2.00 1.46 8"-10" Moist. loose 0.155 0.19 0.015 r. 29-30 1.09 2.64 1.60 1.20 10"-12" Moist. loose 0.182 1.27 0013 ay 3 0.42 2.16 1.08 0.62 10"-12" Wet. packed 0.053 0.12 0.002 ay 1 0.98 2.16 1.60 1.04 12" 18" Moist. loose 0.046 0.12 0.004 May 12-13 1.16 1.20 0.56 0.48 2'-3' Wet. packed 0.262 0.24 0.001 ay 1 1.99 7.44 6.08 3.40 2‘-3' Saturated 1.368 6.03 0.096 May 15-16 0.92 2.28 1.60 1.54 2'-3' Saturated 0.586 0.76 0.005 ay 24-25 0.43 1.68 1.20 0.68 3‘-4' Saturated 0.007 0.01 May 29 1.04 3.60 1.80 1.22 4‘-5' Moist. packed 0.318 1.07 May 31 1.36 3.60 3.16 1.92 4‘-5 Wet 0.821 5.68 0.010 Iune 20 0.79 1.32 0.84 0.56 5'-6‘ Moist 0.079 0.11 Sept. 12-13-14 2.73 3.00 2.16 1.64 Open Moist. cloddy 0.252 0.09 0.004 Nov. 1-2-3 1.88 3.36 2.56 1.88 Open Loose 0.479 0.20 0.006 Nov. 5-6 0.35 1.08 0.60 0.32 Open Wet 0.054 0.03 Nov. 15-16 2.68 4.32 3.60 2.90 Open Wet 1.421 2.78 0.001 Nov. 25-26 0.88 3.84 2.00 1.00 Open Wet 0.346 0.44 Dec. 9-10-11 2.60 2.28 1.08 0.74 Open Wet 0.856 0.48 T Total yearly 45.84 8.517 20.38 0.183 1947 Ian. 16-17-18-19 2.57 0.48 0.40 0.32 Open. flat Wet 0.260 0.02 ar. 12 0.93 1.68 1.12 0.88 Planted Moist. loose 0.062 0.01 0.004 Mar. 18 1.40 0.96 0.64 0.52 Planted Wet 0.120 0.04 0.003 Apr. 12-14 1.68 3.60 2.56 1.48 2"-3" Moist. loose 0.425 0.30 0.011 Apr. 19 1.68 7.20 4.40 3.24 2"-3" Wet. packed 1.322 4.87 A r. 24-25 0.73 1.44 0.88 0.50 6"-8" Wet. packed 0.055 0.11 ay 8-9 1.25 1.20 0.76 0.50 8"-10" Loose. dry 0.006 0.01 May 17-18 1.48 6.00 4.08 2.46 14"-16" Wet. packed 0.737 2.05 0.002 May 20 1.35 4.80 4.00 2.66 14"-16" Wet. packed 1.062 4.28 Total yearly 27.23 4.049 11.69 0.020 1948 Apr. 12-13 1.27 2.04 1.20 1.20 3"-5" Dry 0.107 0.06 May 18 1.33 2.40 2.00 1.60 3"-4" Moist. loose 0.615 0.73 Iune 28 3.20 3.60 2.56 2.48 6"-7" Dry. cracked 0.989 1.92 0.012 Iuly 2-3 1.00 2.16 1.28 0.96 6"-7" Wet. packed 0.526 0.33 0.009 Total yearly 18.98 2.237 3.04 0.021 1949 Mar. 20-21 2.11 3.24 2.84 2.10 Planted Dry. loose 0.650 0.85 pr. 9 0.51 3.00 1.64 0.98 2"-4" Wet. packed 0.161 0.60 Apr. 19-20 0.98 0.48 0.28 0.18 4"-6" Wet. packed 0.099 0.04 Apr. 24-25 2.61 4.56 3.24 2.12 4"-6" Wet. packed 1.136 1.80 Apr. 28 1.39 4.08 2.76 1.44 4"-6" Saturated 0.874 1.78 0.002 Iune 14 a.m. 1.32 3.60 3.24 2.50 5'-6' Dry. cracked 0.431 0.41 Iune 14 p.m. 1.21 3.34 2.72 2.04 5'-6' Wet 0.795 1.43 Iune 22-23 1.72 3.96 3.05 2.52 5'-6' Moist 1.018 2.84 0.005 Iune 24-25-26 0.73 1.08 0.60 0.32 5'-6' Wet 0.072 0.06 Iuly 3 0.53 2.52 1.68 0.98 5'-6' Moist 0.152 0.20 Iuly 31 1.23 3.00 1.76 1.26 Matured Moist 0.205 0.18 Oct. 21-22-24 4.15 3.12 2.00 2.00 Open Dry. cracked 0.727 0.21 Total yearly 32.26 6.320 10.39 0.007 1950 Feb. 9-10-11-12 2.87 4.44 3.32 2.06 Open. flat Saturated 0.351 0.26 0.002 Apr. 2 0.79 3.00 2.40 1.58 Dry. loose 0.109 0.11 Apr. 13 1.16 1.08 0.76 0.58 Dry. loose 0.185 0.05 Apr. 15-16-17 2.55 4.56 2.40 1.66 Wet 1.158 0.68 0.003_ May ll 0.72 2.88 2.00 1.06 8"-12" Moist 0.121 0.19 May 13 1.14 4.80 3.84 2.08 8"-12" Wet 0.644 0.77 0.006 Sept. 10 1.56 6.00 4.00 2.44 Open Dry. cracked 0.493 0.33 Sept. 16 0.66 1.80 1.08 0.60 Open Moist 0.045 0.03 Total yearly 22.41 3.106 2.42 0.011 1951 Apr. 29 1.72 2.40 1.76 1.44 8"-10" Dry 0.288 0.17 May 0.93 5.28 3.60 1.86 12"-14" Moist 0.498 0.66 May 5-6 1.21 2.40 2.32 1.44 12"-14" Wet. packed 0.493 0.91 May 10 0.61 2.04 1.28 1.06 12"-14" Wet. packed 0.216 0.49 May 14-15 1.89 2.88 1.92 1.50 14"-18" Wet 0.955 0.91 May 22 0.80 4.56 2.48 1.38 2'-3' Moist 0.010 0.02 May 24-25 1.25 1.92 1.60 1.28 2'-3' Wet 0.252 0.15 Iune 11 1.16 3.12 1.44 1.16 5'-6' Dry 0.209 0.18 Sept. 12-13 3.74 4.20 3.60 3.30 Harvested Dry 1.137 0.50 Sept. 25 1.33 4.56 2.80 1.98 Harvested Moist 0.350 0.17 Total yearly 27.74 4.408 4.16 54