f‘? 5' b swam- 90/ flcyumes for Soil improvement for flatten and 60m 14pm’! I958 TEXAS AGRICULTURAL EXPERIMENT STATION R. D. LEWIS. DIRECTOR. COLLEGE sTATION-, TEXAS, SUMMARY This bulletin reports the results of experi- ments conducted during 1949-55 0n the Upland Farms, College Station; on the A&M Plantation located on bottomland near College Station; and Substation No. 6, Denton, to develop more practi- cal systems of managing legumes for soil im- provement. Hairy vetch, Willamette vetch and Dixie Wonder peas as winter ‘green-manure crops be- tween annual corn corps produced only small increases in the corn yield on the Upland Farms at College Station during the 7 years. The legumes failed to produce. larger increases in corn yield mainly because of inadequate soil moisture during the fruiting and ripening period of corn (May and June), when the corn was using maxi- mum amounts of water. Rainfall in May and June influenced the yield of corn more than the treat- ments. The spacing of corn plants 18, 24 and 30 inches apart in 40-inch rows had no significant effect on the corn yield. There was no differential response of plant spacing to irrigation. Irrigation produced a marked increase in the yield of corn in 1954. Plowing under Hairy vetch, Willamette vetch, Dixie Wonder peas, Austrian Winter peas and Singletary peas preceding cotton in a 2-year rotation of cotton and corn had no significant effect on the average cotton yield on the Upland Farms for 7 years. However, Hairy vetch, Dixie Wonder peas and Austrian Winter peas produced larger yields of green matter and added more nitrogen to the _soil than Singletary peas or Willamette vetch. Thelack of rainfall was the first limiting factor in cotton production under these conditions. Legumes turned under for cot- ton had only a small residual effect on the yield of corn which followed the cotton. The applica- tion of 60 pounds of nitrogen per acre produced small but highly significant increases in the corn ACKNOWLEDGMENTS Grateful acknowledgments are made to M. J. Norris, associate agronomist, Substation N0. 23, McGregor, Texas, who conducted the work at Sub- station No. 6, Denton, Texas, in 1950-51; to J. H. Gardenhire, assistant agronornist, Substation No. yield for 1950 and 1955 and in the average for the 6 years, 1950-55,:‘-‘; r Continuous corn planted in every row fertilized with 60 pounds of nitrogen per acre the best treatment used at the A&M Plantar, This treatment produced the highest yields, ' bushels of corn on 1 acre in 2 years, as com with the next highest yield, 79.2 bushels, for _ in alternate pairs of rows in a 2-year rota r with Melilotus indica. There was no real dif ence between the 4-year average yield of unf_ lized continuous corn grown in every row grown in alternate pairs of rows. -~ Corn preceded by 1 year of fall-seeded M H‘ sweetclover and corn preceded by 2 years" spring-seeded Madrid produced almost ident average yields on the A&M Plantation. Fall ing was significantly better than spring when Madrid sweetclover was used in a 2- rotation with corn. In the 3-year rotatio years of spring-seeded Madrid sweetclover»- green manure produced a significantly hi average yield of corn than fall-seeded alfalfal hay. This difference may have been caused p by the superiority of Madrid in competing Johnsongrass infestations and by the remov the alfalfa as hay. I At Denton, Austrian Winter peas, l- Wonder peas, Hubam sweetclover and M A sweetclover in cropping systems with corn, and without nitrogen, produced significantly lo, average yields of corn than continuous corng fact, the cropping systems that included‘ Hu sweetclover for seed or Madrid sweetclover green manure produced significantly lower a age yields of corn than did continuous Furthermore, the application of 60 pounds, nitrogen per acre to corn each year, in additi ‘ the legumes, did not increase the average yie, corn. Deficiency of soil moisture was the c limiting factor in corn yields at Denton du, the period of these experiments. I 6, who carried on the work at Denton in 1952- and t0 R. L. Smith, head 0f the Statistical La atory, for statistical analysis of the results; tained 0n the Upland Farms and the A&M Play tion, College Station, Texas. ‘ HE UPLAND SOILS IN EAST TEXAS generally are w in organic matter, nitrogen, phosphorus and tash, and consequently are naturally l0W in * oductivity (1). These soils, however, respond <- soil management practices, such as fertilizers d green manures, under favorable rainfall (2, .5). p During the past 25 or 30 years, the Depart- g ent of Agronomy has conducted experiments to termine the adaptation of legumes to Texas j: to evaluate them for soil improvement for Qrious crops. Some of this work (3) showed $1 t Hairy vetch was one of the most dependable Ynter legumes for East Texas. Other Work (6) showed that plowing under airy Vetch increased the yield of cotton 40 per- ent over a period of 10 years, 1937-46, atCollege , tion. Vetch increased the cotton yield 75 to ~- percent and practically doubled the corn yield Tyler. Plowing under vetch also increased e cotton yield 75 percent at Nacogdoches. Later, some new, legumes, especially Dixie onder peas, Singletary peas and Willamette etch, became available as forage and soil-im- j ving crops. The work on soil and crop manage- was revised and expanded in 1948-49. Dixie onder peas, Willamette vetch, Austrian Winter is and Singletary peas were included, along "th Hairy vetch, in the revised work on the land Farms at College Station to evaluate .- for soil improvement. The experiments on‘ e A&M Plantation, near College Station, in- ded Dixie Wonder peas, Hubam and Madrid ‘eetclovers, alfalfa and Melilotus indica. in dif- f nt cropping systems. Somewhat similar work ‘s started at Denton in 1949 to ascertain the ‘ ue of Austrian Winter peas, Dixie Wonder *= and Hubam and Madrid sweetclovers for improvement in various cropping systems th corn. CORN ON THE UPLAND FARMS . Experiments were conducted with Hairy y. ch, Willamette vetch and Dixie Wonder peas I soil-improving crops for corn on the Upland _ ms at College Station during 1949-55. The umes were grown during the fall and winter f~- pectively, professor, associate professor and instruc- r, Department of Agronomy; junior agronomist, Sub- l tion No. 6, Denton, Texas; and farm manager, Farm rvice Department, College Station, Texas. .Cqmwwsflh"5m7Z%wnwwuaay%r6hflmrand4%mn E. B. REYNOLDS, H. E. REA, ELI WHITELEY, P. A. RICH and J. E. ROBERTS* between annual corn crops. The main objectives of the work were: to determine the relative value of these legumes as soil-improving crops, to determine whether the legumes will furnish enough nitrogen for corn and to ascertain whether there is any differential response‘ of spacing of corn plants to green manure and fertilizers. Seed of the three legumes were inoculated and planted on well-prepared seedbeds as soon as practicable after the corn was harvested. The soil was fertilized with 0-60-60 fertilizer when the legumes were planted. This fertilizer is equiva- lent to 60 pounds of phosphoric acid (P205) and 60 pounds of potash (K20) per acre. The legumes were allowed to grow until about February 15, when they were plowed under. A recommended corn hybrid was planted on the land about_Marc_h 15, the optimum planting date for corn 1n this part of Texas. CONTENTS Summary ------------------------------------------------------------------ -- 2 Acknowledgments .................... -------------------------- -- 2 Introduction ------------------------------------------------------------ -- 3 Corn 0n the Upland Farms --------------------------------- 3 Legumes and Fertility Treatments . . . . . . . . - - - - -- 4 Yield of Corn ---------------------------- ---------------------- -- 4 Effect of Legumes and Fertlllzel‘ ------------- 5 Effect of Spacing ------------------------------------------ -- 5 Effect of Irrigation ....................................... -- 5 Yield and Nitrogen Content of Legumes ...... ._ 5 Cotton and Corn in Rotation on the Upland Farms ..... -------------------------------------------- -- 5 Yield of ‘Cotton ...................... .. ---- -- 7 Yield of Corn ......... .. . ---- -- 7 Effect of Nitrogen -------------- --_--; ------ -- - ---- -- 8 Effect of Legumes and Fertllllel‘ -------------- ~- 3 Yield and Nitrogen Content of Legumes ...... .. 9 Corn on the A&M PIaIItBtiOIl ------------- -------------- -- 9 Soils and Rainfall .............................................. ~10 Yield of Corn in Different Cropping Systems ------------------------------------- ------ ~10 Effect of Row Systems on Yield of Corn ...... ..11 Corn at Denton ------------------------------------------------------ ~11 Cropping Systems ..... ------------------------------------ --11 Soils and Rainfall ---------------------------------------------- ~12 Yield of Corn .............................. --_- -------------------- ~12 Effecfof Legumes and Cropping Systems..12 Effect of Nitrogen ........................................ --13 Discussion of Results ............. ............................ --13 Literature Cited ---------------------------------------------------- ~14 aevviv Legumes and Fertility Treatments The following legume and fertility treat- ments were used in the experiment: 1. Hairy vetch fertilized with 0-60-60. 2. Hairy vetch fertilized with 0-‘60-60; 30 pounds of nitrogen per acre were applied when the corn was planted and 60 pounds were applied as a sidedressing. 3. Willamette vetch fertilized with 0-60-60. 4. Willamette vetch fertilized with 0-60-60; 30 pounds of nitrogen per acre were applied when the corn was planted and 60 pounds were applied as a sidedressing. 5. Dixie Wonder peas fertilized with 0-60-60. 6. Dixie Wonder peas fertilized with 0-60-60; 30 pounds of nitrogen were applied when the corn was planted and 60 pounds were applied as a side- dressing. 7. 0-60-60 fertilizer applied to corn. _8. 90-60-60 applied to corn; all P205 and K20 applied at planting; 30 pounds of nitrogen applied at planting and 60 pounds as a sidedressing. _ Three spacings of corn plants, 18, 24 and 30 inches between plants in 40-inch rows, were in- cluded to determine the effects of spacing on the yield of corn. These spacings provided 8,700, 6,500 and 5,200 plants per acre, respectively. The work was conducted on Lufkin fine sandy loam soil, a planosol. This soil occurs in the south- ern parts of the East Texas Timberlands, mainly in_the area known as the post oak strip. Lufkin soils occur to some extent in other parts of the TABLE 1. AT COLLEGE STATION. 1949-55 YIELD or com: WHICH RECEIVED AND WHICH DID NOT RECEIVE NITROGEN FOLLOWING LEG u... Bushels shelled corn per acre region. They are gray and rest on dense, plasti clay subsoils. They have very slow drainag‘ through the soil and on smooth flat areas th soils remain wet for long periods. Lufkin so' u: are drouthy. They are not naturally productive but, with careful treatment, moderate yields o general farm crops are obtained if moisture con ditions are favorable. Theyrésults obtained in this experiment at College Station’ should be applicable; generally to Lufkin soils throughout the regioni Yield of Corn The corn yield obtained during the 7 years or the experiment are shown in Table 1. Good yieldsf were obtained only in 1955, when the average yield of all the treatments was about 51 bushels per acre. Low to medium yields in the other? years were caused bv deficient or poor distribution, of rainfall, unavoidable lateness of planting of; replanting necessitated by corn rootworm dam: age. In 1950 medium yields, averaging about; 28 bushels for the several treatments. were caused by severe corn rootworm damage. In an adjoin- ing experiment, which suffered little or no damage by the rootworm, the average yield nearly 50 bushels per acre. . Table 2 shows that the rainfall was abovet ; long-time average of 38 inches only in 1949 an‘ 1953. Although apparently there was sufficien rainfall in June of 1949 and 1953, by the middl of June of each year there was not enough moif ture in the soil to supply the needs of the c0 during its critical period. In 1955 rains occurr in June at the time the corn plants were usi f maximum amounts of water. These timely rai , account for the higher yields in 1955, althoug the total rainfall for the years was about ._ inches below the long-time average. e Treatment 1949 1950 1951 1952 1953 1954 1955 Averag Hairy vetch plus N‘ 26.6 26.2 19.1 25.1 30.1 31.8 51.8 31.0 Hairy vetch 25.1 27.9 21.6 24.1 33.1 33.5 52.2 30.1 Average 25.8 27.1 20.3 24.6 31.6 32.7 52.0 30.5‘ Willamette vetch plus N‘ 28.9 26.3 18.4 24.0 29.7 32.3 55.1 30.6 Willamette vetch 25._6 _ 26.3 22.9 24.1 30.9 32.4 45.9 29.6 Average 27.3 26.3 20.7 24.1 30.3 32.3 50.5 30 l’ Dixie Wonder peas plus N‘ 29.7 31.2 18.5 24.6 29.2 31.5 52.2 31. Dixie Wonder peas 28.3 28.1 22.7 28.1 32.6 34.0 50.2 31. Average 29.0 29.7 20.6 26.3 30.9 32.7 51.2 31.5 l; 0-60-60 plus N‘ 27.4 34.8 18.5 24.0 30.1 31.9 55.0 31.6 0-60-60 24.5 22.5 23.1 21.6 ' 30.0 30.1 45.8 28.5 Average 25.9 28.7 20.8 22.8 30.1 31.0 50.4 30.1‘ Average with nitrogen 28.2 29.6 18.6 24.4 29.8 31.9 53.5 30.9 Average without nitrogen 25.9 26.2 22.6 24.5 31.7 32.5 48.5 30.3 L. S. D. for nitrogen: .05 NS NS 2.6 NS NS NS 4.9 NS L. S. D. for nitrogen: .01 NS NS NS NS NS ‘ NS 8.0 NS ‘Theseplots received 90 pounds of nitrogen per acre each year. i “The difference in the average yields of any two treatments must equal or exceed 1.1 bushels to give odds of 19 to 1 that s difference is real and not due to chance. 4 TABLE 2. RAINFALL IN INCHES AT COLLEGE STATION, 1949-55. AND AVERAGE FOR 65 YEARS Average 1949 1950 1951 1952 1953 1954 1955 1949-55 65 years --- uary 6.05 1.30 .61 3.95 2.13 1.12 2.35 2.50 3.25 iebruary 3.59 3.62 2.54 2.58 2.65 .83 5.56 3.05 2.92 =drch 3.05 2.84 5.44 1.57 2.44 .77 .37 2.35 2.81 pril 6.19 5.26 1.38 5.19 6.93 3.71 3.80 4.64 3.73 v cy .87 5.52 2.91 7.23 7.27 5.63 3.94 4.77 ~ 4.90 ~ e 3.98 6.26 . 1.51 .49 3.58 .14 3.00 2.71 3.17 y 3.26 2.81 .52 1.20 2.00 2.89 1.32 2.00 2.54 , ugust .89 .73 .51 T 2.95 .14 .74 .85 2.32 _ ptember 3.31 2.15 4.53 1.88 3.03 .83 1.30 2.43 2.72 r ober 8.40 .33 .53 .00 4.46 4.69 .67 2.73 2.89 vember .06 a .12 2.54 7.09 2.68 1.48 .60 2.08 3.29 ‘ cember 7.35 .10 1.34 4.47 4.49 2.73 1.64 3.16 3.78 47.00 31.04 24.36 35.65 44.61 24.96 - - 25.19 33.127 38.32 Total ect of Legumes and Fertilizer The highest average yield of corn, 31.5 _ shels per acre for the 7 years, was obtained by owing under Dixie Wonder peas, Table 1. This ield was significantly larger than the average 'elds of corn from the treatments of Willamette tch and 0-60-60. The application of 90 pounds of nitrogen per ire produced a significant decrease in the corn ‘eld for 1951 and an increase in yield for 1955. , itrogen, however, had no appreciable effect on x e average yield of corn for the 7 years, Table 1. The effects of the legumes and nitrogen on the ‘feld of corn were not enough to be of economic i, portance. i- ect of Spacing _ The three spacings of plants, 18, 24 and 30 ches, produced almost identical average yields - corn for the 7 years, Table 3. In most years, wever, moisture, not nitrogen or spacing, is the t st limiting factor in yield of corn on this soil. Apparently the soil in most years has Jrnished enough nitrogen for the population of nts provided by the spacings used. With equate moisture and higher levels of nitrogen, wever, the spacing of plants probably would ave a greater influence on yield of corn. i - ect of Irrigation _ Irrigation facilities became available in 1954 d two of the three blocks of corn in the experi- nt were irrigated June 14, 15 and 16, when the r; plants were showing great stress from lack “moisture. This irrigation was made several LE 3. YIELD OF CORN IN DIFFERENT SPACINGS AT ILLEGE STATION. 1949-55 . i; :_, ,? Spacing Yield, bushels per acre p between ‘mtslinches 1949 1950 1951 1952 1953 1954 1955 Average 18 28.2 28.6 21.2 25.5. 31.2 30.8 49.5 30.7 24 25.3 27.8 19.5 24.2 30.0 32.9 52.2 30.3 30 26.9 27.4 21.1 23.6 30.9 32.9 51.5 30.6 days too late to produce maximum yields; how- ever, the irrigated land made an average yield of 36.8 bushels per acre and the nonirrigated land, 23.0 bushels, Table 4. Spacing and application of nitrogen had no appreciable effect on yield of corn under irrigation. Yield and Nitrogen Content oi Legumes The yields of green and air-dry matter and nitrogen content of the legumes used in this Work are given in Tables 5, 6, 7 and 8. Yields of green and air-dry matter (forage) were obtained if the legumes made sufficient growth. The winter of 1948-49 was unusually severe for Central Texas, with a minimum of —-3° F. on January 31, 1949. As a result of this extremely low temperature, together with dry weather and enforced late planting, the legumes made very little growth. Only the Dixie Wonder peas made sufficient growth to estimate yields of green matter. Nor- mally these peas would have been killed by this low temperature, but they were protected by a snow cover 6 to 8 inches deep. Yields were not obtained in 1951 and 1954 because the legumes made little growth as a result of the dry weather or severe freezes or both. Willamette vetch and Dixie Wonder peas produced low yields in 1953; Hairy vetch made scanty growth but not enough to determine yields. Fairly good yields were ob- tained for the three legumes in 1955. Yields were obtained from Dixie Wonder peas during 5 of the 7 years, from Willamette vetch, 4 years and from Hairy vetch, 3 years. Dixie Wonder peas produced an average yield of 12,040 pounds of green matter per acre TABLE 4. YIELD OF CORN IN DIFFERENT SPACINGS UN- DER IRRIGATION AND ON DRYLAND AT COLLEGE STA- TION. 1954 Spacing. inches between Bushels per acre Plants in "W Irrigated Nonirrigated Average 18 33.8 24.9 30.8 24 938.8 21.5 32.8 so _ 38.1 22.5 32.9 Average 116.8 23.0 TABLE 5. YIELD OF GREEN AND AIR-DRY MATTER OF HAIRY VETCH. WILLAMETTE VETCH AND DIXIE WONDER PEAS AT COLLEGE STATION, 1949-1955 . TABLE 7. PERCENTAGE OF NITROGEN IN AIR-DRY TER IN TOPS OF LEGUMES WHEN PLOWED UNDER COLLEGE STATION. 1949-55 r Yield. pounds per acre variety Average. 1949 1950 1952 195a 1955 195“ 1952. 1955 Green matter Hairy vetch 1132012920 9.140 11.099 Willamette vetch 6.690 4.370 4.760 10.150 7.070 Dixie Wonder peas 3.260 7.340 14.470 5.740 14.310 12.040 Air-dry matter 2.250 2.440 2.250 2.313 690 2.260 1.390 900 2.590 2.140 Hairy vetch Willamette vetch 950 960 Dixie Wonder peas 520 1.440 2.390 in 1950, 1952 and 1955; Hairy vetch yielded 11,093 pounds; and Willamette vetch made 7,070 pounds, Table 5. In 1950, 1952 and 1955 Hairy vetch contained, 0n the average, 22.0 percent of air-dry matter; Willamette vetch, 21.5 percent; and Dixie Wonder peas, 18.1 percent, Table 6. On the average, Hairy vetch had a slightly higher percentage of nitrogen than Willamette vetch or Dixie Wonder peas, Table 7. These results possibly indicate that Dixie Wonder peas would be a more dependable soil- improving crop for corn than Hairy vetch or Willamette vetch because it was a more consistent yielder. But there are other factors to consider. During the 7 years of the experiment, Hairy vetch produced a total of 33,280 pounds of green matter per acre, Willamette vetch 25,970 pounds and Dixie Wonder peas 45,120 pounds. During the ex- periment the tops of Hairy vetch added 263 \ pounds of nitrogen per acre to the soil, Willamette vetch added 168 pounds and Dixie Wonder peas 261 pounds. These data reveal the hazards and difficulties involved in the use of winter annual legumes as soil-improving crops for corn. The lack of rain- fall in the fall frequently delays preparation of the land for seeding legumes. Freezing tempera- tures in the winter and lack of rainfall may result in low yields of green matter or a total failure. Rains occurring at the time the legumes should be turned under in late winter may delay turning, and consequently delay corn planting. TABLE 6. PERCENTAGE OF AIR-DRY MATTER IN TOPS OF LEGUMES WHEN PLOWED UNDER AT COLLEGE STA- TION. 1949-55 Average Avera y, Legume 1949 1950 1952 1959 1955 Legume 1949 1950 1952 1959 1955 1955 1955” Hairy vetch 21.4 19.0 25.7 22.0 Hairy vetch 90 91 82 Willamette vetch 20.4 22.0 14.5 22.2 21.5 Willamette vetch 37 31 31 69 Dixie Wonder peas 16.0 19.6 16.5 15.7 18.1 18.1 Dixie Wonder peas l7 52 73 38 81 6 . Aver Legume 1949 1950 1952 195a 1955 ’ 1 I Hairy vetch 4.01 e935 9.9a 9 Willamette vetch 9.99 9.20 4.55 9.04 9 Dixie Wonder peas 3.33 3 61 3.06 4.17 3.14 3 In this experiment the use of Hairy ve Willamette vetch and Dixie Wonder peas as -_f-._ manure crops for corn was not profitable practical. ‘a COTTON AND CORN IN ROTATION - oN THE UPLAND FARMS This experiment was conducted on the Upla Y Farms at College Station for 7 years, 1949- The objectives of the work were to determine t soil-building value of Austrian winter peas, D" Wonder peas, Singletary peas, Willamette ve v and Hairy vetch for cotton in a 2-year rotati of cotton and corn and to determine whet there is any residual effect of legumes and fe =1 lizer on the yield of corn. The work was conduc _~I on Lufkin fine sandy loam. The work involved the growing of winter ' gumes preceding cotton inla 2-year rotation wi corn in which the legume was grown each w» The legumes were inoculated and planted as e I as possible each fall and 90 pounds of availa phosphoric acid (P205) and 90 pounds of pot j (K20) per acre were applied at planting (0-90-9 The legumes were plowed under in the sp ' and followed by cotton. Corn followed the cot the second year and received only the resid I effects of the legumes and fertilizer except wh nitrogen was applied to the corn. The work w, started in the fall of 1948, with legumes be' planted on half of the land. The legumes we turned under in the spring of 1949 and cott planted on the land. Corn was planted on the =9 of the land on which no legumes were planted. i To determine the residual effects of legum and fertilizer on the yield of corn, two plots e, each legume were established in each replicatii Each plot received a 0-90-90 fertilizer per a , when the legumes were planted; in the seco TABLE 9. POUNDS or NITROGEN PER ACRE IN TOPS LEGUMES WHEN PLOWED UNDER AT COLLEGE sum 1949-55 . o jyear when the plots were planted to corn one 4 plot received a total of 60 pounds of nitrogen per acre, 30 pounds at planting and 30 pounds as a sidedressing. The other plot received no nitrogen. A The following legume and fertility treat- ‘ ments were used: 1. Hairy vetch fertilized with 0-90-90. 2. Hairy vetch fertilized with 0-90-90; 60 pounds of nitrogen per acre applied to corn the i» second year. 3. Austrian Winter peas fertilized with 4. Austrian Winter peas fertilized with 4 0-90-90; 60 pounds of nitrogen per acre applied to ; corn the second year. 5. Willamette vetch fertilized with 0-90-90. a 6. Willamette vetch fertilized with 0-90-90; ; 60 pounds of nitrogen per acre applied to corn the ; second year. 7. Dixie Wonder peas fertilized with 0-90-90. I 8. Dixie Wonder peas fertilized with 0-90- » 90; 60 pounds of nitrogen applied to corn the second year. 9. Singletary peas fertilized with 0-90-90. y 10. Singletary peas fertilized with 0-90-90; ~ 60 pounds of nitrogen applied to corn the second f year. 11. Fertilizer, 60-90-90 applied to cotton. 12. Fertilizer, "60-90-90 applied to cotton; 60 , pounds of nitrogen per acre applied to corn the second year. 13. Check, 0-90-90 applied to cotton. 14. Check, 0-90-90 applied to cotton; 60 pounds of nitrogen per acre applied to corn as sidedressing the second year. l _ Yield oi Cotton The results obtained with cotton during 1949- 55 are given in Table 9. Excellent yields for Lufkin soil were reported only in 1955, when the average yield for the seven treatments was 631 pounds of lint per acre. This high yield was due partially to the two irrigations of 2 inches each, applied July 11 and August 8. Good yields, averaging more than 400 pounds of lint per acre, were obtained in 1949, 1953 and 1954. The lowest yields were reported in 1951-52. Moisture was the first limiting factor in yields in 1951-52 as indicated by the low‘ rainfall in June, July and August, Table 2. Moisture also probably restricted yields in 1950, 1953 and 1954. Two irrigations were applied in 1954, but irriga- tion facilities did not become available until the cotton was wilting. Barely significant differences in yields be- tween treatments were found only in 1949 and 1953. No significant differences in the average yields of the several treatments were found for the 7 years. Highly significant differences in yields, however, occurred between years. From these results it is difficult to reach definite conclusions regarding the relative value of the several treatments, especially the legumes. The results seem to indicate that, the legumes furnished enough nitrogen for cotton yields up to 1 bale per acre (500 pounds of lint). The 60- 90-90 treatment produced the highest average yield, 387 pounds of lint per acre, or only 22 pounds more than the low yield of 365 pounds for the 0-90-90 treatment. This small difference in yield would hardly justify the cost of purchasing and applying 60 pounds of nitrogen. Since there were no untreated check plots in the experiment, it is not possible to determine the real effect of the 0-90-90 fertilizer, which was the basic treatment on every plot. Previous work on the same soil, however, showed that the soil responded to applications of nitrogen, phosphorus and potash for cotton. Yield oi Corn The yields of corn in this experiment were erratic and varied from year to year, depending on the amount and distribution of rainfall dur- ing the fruiting and ripening periods. The yields ranged from about 50 bushels per acre in 1950 to TABLE 9. YIELD OF COTTON FOLLOWING LEGUMES FOR SOIL IMPROVEMENT AT COLLEGE STATION, 1949-55 Treatment Pounds oi lint per acre 1949 1950 1951 1952 1953 1954 1955 Average A Hairy vetch 452 265 278 202 397 380 671 378 Willamette vetch J 389 262 254 192 399 395 615 356 Austrian Winter peas ".. 407 295 254 197 398 390 656 371 Dixie Wonder peas ti" 391 282 251 194 404 ‘380 613 359 ’ Singletary peas 449 277 274 199 413 404 684 386 60-90-90 392 288 266 202 485 444 631 387 Y 0-90-90 387 300 251 201 440 425 548 365 Average 410 - 281 261 198 419 403 631 372 a L.S.D.: .05 51 NS NS NS 82 NS NS NS .01 70 NS NS NS 150 NS NS NS TABLE 10. YIELD OF CORN GROWN IN ROTATION WITH COTTON FOLLOWING LEGUMES AT COLLEGE STATION. 19 i‘ Yield bushels per acre Treatment ' 1 1950 1951 1952 1953 1954 1955 Aver Hairy vetch‘ 53.2 8.0 6.0 20.6 5.2 42.6 2 Hairy vetch 39.1 9.4 12.0 19.6 8.9 42.6 21 Willamette vetch‘ 47.6 5.1 4.5 16.6 9.9 ;._ 45.5 21 , Willamette vetch 33.2 8.7 17.1 19.3 10.6 35.1 20. Austrian Winter peas‘ 47.8 7.0 9.9 16.8 5.7 ' 44.7 2 l‘; Austrian Winter peas 32.4 7.4 9.3 18.1 9.0 41.9 19. a Dixie Wonder peas‘ 47.1. 7.0 9.2 20.4 8.0 45.0 22. Dixie Wonder peas 30.2 11.3 10.2 18.7 8.8 40.5 2 Singletary peas‘ 51.1 6.2 9.5 19.6 5.9 42.9 2 j Singletary peas 34.8 8.4 8.9 20.3 8.0 43.4 20 ‘ 60-90-90‘ 45.4 9.0 13.9 16.0 11.1 42.9 23 60-90-90 40.6 6.3 8.1 17.1 6.4 46.1 20.9- 0-90-90‘ 55.2 7.2 10.8 17.9 9.4 45.3 24.3- 0-90-90 33.2 8.7 12.6 18.2 9.3 29.1 18.5;- Average ,1 Nitrogen 49.6 7.1 9.1 18.3 7.9 44.1 22.74‘ No nitrogen 34.8 8.6 11.2 18.8 8.7 39.8 20.3“ L.S.D. for nitrogen: .05 4.9 NS NS NS NS 2.41 1. .01 7.4 NS NS NS NS 3.30 ‘These plots received 60 pounds of nitrogen per acre. 30 pounds at planting and 30 pounds as a sidedressing. 5 bushels in 1951, Table 10. A yield of 50 bushels per acre is excellent and unusual on Lufkin soil. The good yields in 1950 resulted from fairly adequate and well-distributed rainfall in April, May, June and July. Some individual plots pro- duced yields of about 70 bushels per acre. The yield in 1950 might have been limited by the amount of nitrogen and not by moisture. The low yields in 1951-52 were caused by deficient rainfall in June and July, when the corn needed large amounts of water. The low rainfall and the low water-holding capacity of the Lufkin fine sandy loam emphasize the difficulties of pro- ducing satisfactory yields of corn on this soil. About normal yields for Lufkin soil were obtained l‘ in 1953 and low yields resulted in 1954. An average yield of about 42 bushels per acre was obtained in 1955. Effect of Nitrogen The application of 60 pounds of nitrogen per acre produced highly significant increases in TABLE 11. YIELD IN POUNDS PER ACRE OF GREEN AND AIR-DRY MATTER OF LEGUMES AT COLLEGE STATION. 194 yield of corn in 1950 and 1955 and the aver” yield during 1950-55. In 1951-54 the corn t' received nitrogen produced slightly lower yie“ than the corn that did not receive nitrogen. T _ nitrogen actually reduced the yield of corn 41 cause it produced larger vegetative growth, wh depleted the small amount of available water the soil more rapidly than the corn which did u, receive nitrogen. This small margin of water‘ the soil on the plots that did not receive nitroi resulted in a slightly higher yield on these t; The results obtained during 1950-55 sh that nitrogen increased the yield of corn in y :- of favorable rainfall, but not in years of defici rainfall. Effect of Legumes and Fertilizer Significant differences in yield of co among the legume and fertilizer treatments t’ curred only in 1950 and 1955, Table 10. Th were, however, marked differences in yie among years. .1, ‘l Average Variety _, .v 1949 1950 1952 1953 1954 1949-54 5 yo I Green matter a Hairy vetch 7.240 12,990 14.410 16.970 8.110 9.953 ll. g Willamette vetch 4.830 8.020 5.280 14.410 6.080 6.437 7.7 , Austrian Winter peas 8.530 12.400 13.280 21.000 8.260 10.578 12.6 Dixie Wonder peas 6.470 9.340 12.340 22.920 8.190 9.877 11. Singletary peas 4.480 14.000 9.430 7.590 4.370 6.645 7. ’ Air-dry matter Hairy vetch 1.670 2.780 3.530 . 1.650 2.060 2. 1 Willamette vetch 990 1.630 1.160 2.090 1.480 1.225 1.4;‘, Austrian Winter peas 1.450 2.200 1.930 2.770 1.510 1.643 ‘vi Dixie Wonder peas 1.050 1.840 2.040 3.600 1.500 1.672 l= Singletary peas 840 2.430 1.910 1.200 850 1.205 l. I ‘The legumes did not make enough growth in the winter of ‘Average for 1949. 1950. 1952. 1953 and 1954. 8 1950-51 to obtain yields. Yields are given to the nearest l0 A LE 12. PERCENTAGE OF AIR-DRY MATTER IN THE P GROWTH OF LEGUMES AT COLLEGE STATION. 1949-54 me 1949 1950 1952 195s 1954 Average - ~ vetch 23.1 21.4 24.5 16.1 20.3 21.1 A amette vetch 20.4 20.4 22.0 14.5 24.3 20.3 ' trian Winter peas 17.0 17.7 14.5 13.2 18.3 16.1 'e Wonder peas 16.2 19.7 16.5 15.7 18.3 17.3 letary peas 18.8 17.4 20.3 15.8 19.5 18.4 » Aield and Nitrogen Content o1 Legumes ~‘~ Good yields of forage were obtained in only .of the 7 years, 1950, 1952 and 1953. Medium ‘ 10W yields were obtained in 1949 and 1954. e legumes did not make enough growth in the 1 and winter of 1950-51 to determine yield. ey made fair growth in 1955, but through un- ntrollable circumstances, yields of forage were obtained. g Austrian Winter peas made the highest erage yield of green matter, 12,694 pounds per . re, for the 5 years in which yields were ob- ined, Table 11. Hairy vetch and Dixie Wonder is ranked next in yield of green matter. Hairy vetch made the highest average yield I air-dry matter, 2,472 pounds, as compared with "006 pounds 0f Dixie Wonder peas, Table 11. . The percentage of air-dry matter varied ‘idely among the five legumes and from year to Table 12. Hairy vetch had the highest erage percentage for the period, 21.1. Austrian inter peas had the lowest percentage, 16.1. ._ The percentage of nitrogen also varied con- derably among the legumes and in different ars, Table 13. During 1949-54, Hairy vetch w the highest average nitrogen content, 4.06 rcent of nitrogen in the air-dry tops. Dixie onder peas had the lowest percentage of ‘trogen, 3.51. . Hairy vetch supplied more nitrogen per acre an the other legumes because of its good yield egreen matter, high percentage of air-dry mat- tr and high percentage of nitrogen, Table 14. p or the 5 years, its tops contained. on the average, j 1 pounds of nitrogen per acre. Willamette vetch ind Singletary peas each supplied the lowest ' ount of nitrogen, 57 pounds per acre. g This experiment as a whole, including the ', d of cotton and the yields and nitrogen content g ,5 he legumes, indicates that Hairy vetch, Dixie ABLE 19. PERCENTAGE OF NITROGEN IN AIR-DRY MAT- __ - IN rop GROWTH or LEGUMES AT COLLEGE STATION. _ 9-54 gume 194911950 1952 1959 1954 Average airy vetch 3.68 4.01 4.05 4.51 4.06 4.06 . illamette vetch 3.38 3.89 3.20 4.55 3.78 3.76 . ustrian Winter peas 3.06 4.05 4.80 4.44 3.62 3.99 'e Wonder peas 3.36 3.61 3.06 4.17 3.37 3.51 _ gletary peas 3.71 3.62 4.21 4.28 3.66 3.90 TABLE 14. POUNDS OF NITROGEN PER ACRE IN TOPS OF LEGUMES AT COLLEGE STATION. 1949-54 Legume 1949 1950 1952 1953 1954 Average Hairy vetch 62 112 143 123 67 101 Willamette vetch 33 64 37 95 56 57 Austrian Winter peas 44 89 92 123 55 81 Dixie Wonder peas 35 68 62 150 51 73 Singletary peas 31 92 81 51 31 57 Wonder peas and Austrian Winter peas are more dependable soil-improving crops for cotton on Lufkin and similar soils than Singletary peas and Willamette vetch. CORN ON ‘THE A&M PLANTATION Two experiments with legumes in several cropping systems with corn were conducted on the A&M Plantation near College Station during 1950-53. One experiment involved continuous corn, corn and Dixie Wonder peas, and corn in ro- tation with Melilotus indica, Hubam and Madrid sweetclovers, and alfalfa. In the other experiment, continuous corn, with and without nitrogen, and corn in a 2-year rotation with Melilotus indica, with and without nitrogen applied to the corn at planting, were tested in two separate row systems. Dixie Wonder peas, Melilotus indica, Hubam and Madrid sweetclovers, used as fall-seeded an- nuals were planted during the last week in September, or as soon thereafter as weather con- ditions permitted. Dixie Wonder peas were plant- ed in a drill on each side of the bed as the land was bedded in the fall. The peas were turned under as green manure in the spring at the time the corn was planted. Ordinarily, no previous treatment of the pea vines was necessary to pre- pare them for being turned under. The fall-seeded sweetclovers were close- drilled on flatland and were turned under the following spring as they reached the early bloom stage. For Melilotus indica, this was about the middle of April, for Hubam the first week in May and for Madrid about the middle of May. However, it was not unusual for Hubam and fall- . TABLE 15. RAINFALL IN INCHES AT THE A&M PLANTATION NEAR COLLEGE STATION. 1950-53. AND 16-YEAR AVERAGE Average Month __i_i__ 1950 1951 1952 1953 1950-53 1941-56 lanuary 1.30 0.82 3.17 1.86 1.79 2.71 February 4.23 2.20 4.20 2.77 3.35 2.97 March 2.24 4.91 1.71 2.43 2.82 2.92 April 6.96 .86 . 4.95 8.15 5.23 3.63 May 5.11 3.60 8.14 10.87 6.93 5.54 I une 6.22 1.95 .54 4.44 3.29 3.67 Iuly 4.42 1.40 2.74 3.04 2.90 2.71 August .06 1.50 0.0 3.28 1.21 2.97 September 2.80 6.72 2.06 3.12 3.67 2.75 October .50 .92 0.0 5.55 1.74 2.32 November .39 2.35 8.48 2.39 3.40 2.92 December .2_1 1.28 5.53 4.66 2.92 3.27 Total 34.44 28.51 41.52 52.56 39.26 38.39 seeded Madrid to be turned under at the same time. Spring-seeded Madrid, used as an annual, was planted in close drills on flatland during late February or early March and was turned under for green manure the following September. Spring-seeded Madrid, used as a biennial, was left to grow through the second spring and was turned under for green manure when it reached the early bloom stage. Alfalfa was close-drilled in the fall on plowed land and was harvested for hay for two summers; then the residue was plowed under early in the second September. The legumes were seeded at the rate of 3O pounds of inoculated seed per acre and were fertilized with 60 pounds of phosphoric acid (P205) in 300 pounds per acre of 20 percent superphosphate in a band to the side and slightly below the seed drill at planting. Texas 24 corn was planted as near March 10 each year as the weather permitted. Nitrogen was used as an experimental variable. It was applied in a band 3 to 5 inches to the side and 2 to 3 inches below the corn at planting. Sixty pounds of nitrogen in the form of ammonium nitrate were used. The southern corn rootworm was con- trolled by applying 5 pounds per acre of 40 percent chlordane dust in the corn seed-furrow. Light infestations of Johnsongrass, typical of fields of Miller clay soil in the vicinity of Col- lege Station, occurred on the area at the start of the tests. These infestations increased in the various cropping systems under test. Usually, the longer the soil-improving crop was left on the land before it was turned under, the more the .. J ohnsongrass spread. Alfalfa for hay was a poor competitor with J ohnsongrass. Apparently, the spread of J ohnsongrass interfered with the maxi- mum soil-improving effects of alfalfa in cropping systems in which this crop was grown. Soils and Rainfall This work was conducted on Miller clay soil, an extensive alluvial soil in the Brazos River TABLE 16. YIELD OF SHELLED CORN PER ACRE IN CROPPING SYSTEMS WITH LEGUMES AT THE A.&M. PLANTATI NEAR COLLEGE STATION. 1950-53 Average pounds Cropping system green tops turned bottom. Miller clay is very productive ~f well drained. Although cotton is the main c grown, the soil is Well adapted to many 0t, crops, such as corn, alfalfa and sweetclov Previous work has shown that this soil is relati ly low in nitrogen and responds to applicati of nitrogen. The results of these experime should be applicable to Millerihand associated s“ in the Brazos River bottom ‘from Waco southw and probably to the same soils along the Color River east of Austin. Monthly rainfall during the 4 years of _ experiments, 1950-53, and the average for the years, 1941-56, are given in Table 15. ‘ average rainfall for these two periods 1 practically the same as the 65-year average at t Upland Farms, College Station. A Yield of Corn in Different Cropping Syste The soil-improving crops used in this t were Dixie Wonder peas as winter green man '7 between annual crops of corn; fall-seed_ M elilotus indicct, Hubam and Madrid sweetclov in separate 2-year rotations with corn; and :_ seeded alfalfa and spring-seeded Madrid Z separate 3-year rotations with corn. Table ' shows the cropping systems, the average yields g green manure preceding the corn crop and co yields obtained. = Dixie Wonder peas as a winter green-manu crop between annual crops of corn increased t 3-year average yield of corn for 1951-53 proximately 24 percent above that of continuo corn not preceded by a legume. Fall-seeded M elilotus indica, Hubam a Madrid sweetclovers in 2-year rotations with co increased the 3-year average yield of corn 67, and 85 percent, respectively, above that of c0 tinuous corn not preceded by a legume. Fall se ing was significantly superior to spring seedi when Madrid sweetclover was used in a 2-y rotation with corn. Corn preceded by 2 years of Madrid sw clover yielded 86 percent more per acre t =, continuous corn not preceded by a legume duri Bushels per acre Average 1951- l under’ 1951-52 1950 1951 1952 1959 1950-59 Continuous corn after 5 No green manure 27.9 41.5 40.7 26.5 34.1 36.2‘ Dixie Wonder peas 9.236 43.3 47.9 , 47.6 39.3 44.5 44.9 2-year rotation. corn after 1 year of : Fall-seeded Melilotus indica 38.539 78.1 62.4 65.2 54.0 64.9 60.5" Fall-seeded Hubam sweetclover 56.525 73.4 70.1 72.1 45.5 65.3 62.6 Spring-seeded Madrid sweetclover 24.943 70.9 58.2 67.1 43.3 59.9 56.2 z, Fall-seeded Madrid sweetclover 37.022 74.1 70.6 78.7 52.0 68.8 67.1: 3-year rotation. corn after 2 years of ~ Q Spring-seeded Madrid sweetclover 35.940 80.6 74.0 47.8 67.5 Fall-seeded alfalfa for hay 10.481 67.2 63.4 50.3 60.31 L.S.D.: .05 12.2 13.4 13.1 11.5 5.6 _[]1 16.9 18.5 17.8 15.6 7.5 10 tithe 3-year period 1951-53. It also significantly §outyielded corn preceded by winter peas and 2 gyears of alfalfa for hay. Corn preceded by 2 years of alfalfa for hay _ iproduced 66.6 percent more than continuous corn not preceded by a legume during 1951-53. It also outyielded corn preceded by winter peas, but did Ltnot produce a significantly greater yield than the ;other legume cropping systems. j The advantage of 2 years of Madrid sweet- lover over 2 years of alfalfa for hay in increasing f orn yields may have been due partly to the . fluperiority of Madrid in‘ competing with John- iongrass infestations. “i a iiEfiect oi Row Systems on Yield oi Corn y Two systems of rows were used in growing ‘yrn. Every row was planted to corn in one sys- jm, which is the row system used for growing jrn in most sections of Texas. Alternate pairs rows were planted to corn in the other system. hese were rotated with the adjacent pair of rows rom one season to another. Continuous corn and "orn in a 2-year rotation with Melilotus indica g ere studied in each row system. Half of each lot planted to corn each year was fertilized with 40 pounds of nitrogen per acre and the other half fthe plot received no nitrogen. Table 17 shows e treatments used, the 3-year average yield of een manure preceding the corn and the yield of . rn obtained. All the land devoted to each of the cropping stems in this test contributed to the yield of irn each year except for the 2-year corn-indict» tation in which all corn rows were planted. a _i 0 years were required for all the land in this tation to produce a corn crop. For this reason yield of corn for a 2-year period, as given in . {1 last column of Table 17, is used to show the ‘ lative merit of the various corn-producing sys- ms. On this basis, the highest yield was ob- A tained by planting corn on every row and fertiliz- ing it with 60 pounds of nitrogen per acre. This system produced a total of 112.6 bushels on an acre in 2 years. The next highest yield was 79.2 bushels obtained from corn planted in alternate pairs of rows in the corn-indica. rotation without nitrogen fertilization. Rotating alternate pairs of corn rows with M elilotus indica produced approximately the same yield as fertilizing alternate pairs of corn rows with 60 pounds of nitrogen per acre. The use of nitrogen fertilizer in rotations of corn with M elilotus indica did not increase the average yield of corn, irrespective of the row system used. This indicates that Melilotus indica furnished enough nitrogen for corn or brought about other favorable conditions for good yields. CORN AT DEN TON Previous work conducted with several le- gumes at Denton showed that sweetclovers were well adapted for forage and soil improvement in the area. The work was revised and expanded in 1949 to evaluate more fully the sweetclovers and winter peas as soil-improving crops for corn. Cropping Systems The experiment included Austrian Winter peas, Dixie Wonder peas, Hubam sweetclover and Madrid sweetclover in several cropping systems with corn. The following cropping systems were used: 1. Corn every year. 2. Corn every year with Austrian Winter peas for green manure. 3. Corn every year with Dixie Wonder peas for green manure. 4. Corn in a 2-year rotation with Hubam sweetclover for green manure. BLE 17. YIELD OF CORN PLANTED IN EVERY ROW AND IN ALTERNATE PAIRS OF ROWS IN CROPPING SYSTEMS ON H ER CLAY SOIL AT THE AcSM PLANTATION NEAR COLLEGE STATION, 1950-53 Treatments _ Average B h 1 i _ pounds, pounds Bushels, shelled corn per acre us e s ° ws 1n . corn produced ham Crops nitrogen green tops on an acre per cwre turned under- 1950 1951 1952 1955 Average in 2 em. a 1950-52 Y row Corn None 39.0 33.5 39.9 23.3 1 33.9 67.8 Corn 60 73.7 57.1 54.1 40.3 v 56.3 112.6 Corn-indica None 32.834 92.2 70.4 62.1 45.3 67.5 67.5 Corn-indica 60 33,269 92.6 64.7 64.4 44.0 66.4 66.4 59111919 Corn N599 57.9 57.5 51.7 19.9 51.4 92.9 W ' s Corri; 60 52.1 40.2 38.4 25.3 39.0 78.0 Corn-indica None 16.901 55.6 39.5 39.6 23.6 39.6 79.2 Corn-indica 60 17,530 48.0 42.8 39.2 25.1 38.8 77.6 .D.: .05 7.1 8.0 7.9 4.8 3.4 .01 9.7 10.9 10.8 6.6 4.6 léd. culated by multiplying the average yields for 1950-53 by 2. except the yield for the ‘corn-indica rotation where every row was ll 5. Corn in a 2-year rotation with Hubam sweetclover for seed. 6. Corn in a 2-year rotation’ with Madrid sweetclover for green manure. 7. Corn in a 3-year rotation with Madrid sweetclover for seed. Each crop in each cropping system appeared every year. In systems 2 and 3 the legumes were planted in the fall and turned under in late winter preceding corn. In systems 4 and 6, Hubam and Madrid sweetclovers were allowed to grow for 1 year and then turned under as green manure preceding corn. In systems 5 and 7 Hubam and Madrid sweetclovers were allowed to mature seed, which was harvested. The stubble was then turned under for soil improvement for corn. Beginning in 1951, 60 pounds of nitrogen per acre was applied to one-half of each plot of corn to determine the effect of additional nitrogen on the yield of corn. Since legumes add nitrogen to the soil and may condition it, this treatment was included to evaluate the source of legume benefits. The treatments were laid out in randomized blocks and replicated four times. Soils and Rainfall The work was conducted on Denton clay at Substation No. 6, Denton, in the Grand Prairie. Denton soils, where the surface layers are deep, are moderately productive. These soils are drouthy, especially on the shallow and more steeply sloping areas, where runoff is rapid. On such areas the thin subsoil layers do not afford a large storage of moisture. Denton clay is well * suited to cotton, corn, small grains, sorghums, sweetclovers and a few other crops. Good yields of these crops are obtained under favorable mois- ture conditions. The results of the work conducted on Denton clay at Denton should be applicable generally to this soil and similar soils throughout the Grand Prairie. TABLE 18. MONTHLY AND YEARLY RAINFALL IN INCHES AT SUBSTATION NO. 6. DENTON " The monthly rainfall at Denton for Q years, 1949-55, and the monthly average rai r for 43 years are given in Table 18. The rai for 5 of the 7 years was considerably bel‘ the 43-year average. April, May and June more rainfall than the other months. Yield of The yield of corn fluctuated from year,“ year, depending largely on the amount of rai“ fall in May, June and July. The yields in Ta 19 and the rainfall data in Table 18 indicate t the amount of rainfall in June probably was most decisive factor in corn production. é‘ usually was flowering and fruiting in June y used large amounts of soil moisture. The high. yields were obtained in 1950 and 1955 when gt rains came in May and June. Distribution of r fall apparently was a more critical factor I total rainfall. -* The total rainfall in 1950 was slightly ab“. the 43-year average of 32.25 inches, Table 18. _. rainfall during the other 5 years ranged fr about 3 to 10 inches below the 43-year average. Effect of Legumes and Cropping Systems There were no significant differences in r average yields of corn among the seven cropp'i systems during 1950-55, Table 19. Omitting ‘T, and using 1951-55, the systems of Madrid clover for green manure and Hubam sweetclo for seed produced significantly smaller aver yields of corn than continuous corn. It wo» appear that the differences in plow-up dates ‘ the legumes brought about these differences p yield. Significant differences also occur _ among the yields of corn in the other five c ’ ping systems. " The yields of corn given in Table 19 indi “ that Denton clay without any legume or fertil’ treatment is capable of producing about bushels of corn per acre with adequate moist and other favorable growing conditions. Hui and Madrid sweetclovers increased the yield f -j Average Month , 1949 1950 1951 1952 1959 1954 1955 . - 1949-55 ~49 y y, Ianuary 5.11 4.54 .59 .54 .94 1.92 1.29 2.04 February 9.05 2.20 2.29 2.00 1.07 .20 1.79 1.90 2. March 2.79 .99 .91 2.41 2.99 .79 1.47 1.71 v_ Aprn .92 4.09 1.97 9.49 4.59 2.92 1.99 9.20 9. f May 7.50 5.95 9.29 4.90 4.79 9.99 5.59 5.09 » ' Iune 9.95 4.45 5.92 .90 2.09 9.11 5.99 9.91 1a1y 2.44 5.99 1.90 1.99 2.99 .99 1.10 2.29 August 2.41 2.99 .94 .94 1.79 1.59 .94 1.42 September 4.88 3.98 2.49 .27 1.15 1.83 2.36 2.42 October 9.11 .14 2.09 .09 9.79 9.07 .79 2.29 November .00 .05 1.17 5.07 9.15 .79 .10 1.47 December 1.94 .04 .99 2.19 1.07 1.99 .70 1.15 Total 40.97 94.59 22.79 25.94 29.25 22.52 29.94 29.42 9 r 12 47 bushels to 57 or 63 bushels per acre in ~ under those particular conditions the “s added enough nitrogen or brought about f conditions in the soil that increased the f Oto 15 bushels per acre. During the other j = of the experiment the conditions were not gble enough to produce 48 bushels of corn re. Moisture and not nitrogen was the first g factor in corn yields. Three of the cropping systems apparently reduced the i; corn, as compared with the yield of con- I: corn. L o factors apparently influenced the failure ' mes to increase the corn yield. First, p" legumes usually must be turned under to - a seedbed before they produce sufficient c matter and nitrogen to have a significant on yield of corn. Second, legumes deplete f"sture reserves in the soil to such an extent f: yield of corn is depressed or is not af- . in years having below average rainfall. fr, the difficulty of establishing good a of legumes, the high seed cost and low 'elds following the legumes in this experi- 1 not justify the use of legumes solely as proving crops on the soils of the Denton - Nitrogen .5 e application of 60 pounds of nitrogen per pd no appreciable effect on the average . of corn in the several cropping systems f 1951-55. The plots that received nitrogen an average yield of 21.2 bushels and the , t did not receive nitrogen produced 20.4 Table 19. In 1951, however, nitrogen 5w a marked increase in the yield of corn. This indicates that in years with good rainfall in May, June and July, application of nitrogen probably would be beneficial. DISCUSSION OF RESULTS The results of these experiments show the limitations of using legumes as green-manure crops under limited rainfall and the relation of corn yields to the amount and distribution of rainfall. The lack of adequate soil moisture was the most critical or decisive factor in corn_and cotton yields at College Station and corn yields at Denton. The distribution of rainfall during the fruiting and ripening period had more in- fluence on yield of corn than total yearly rainfall. The intensity of rainfall also is an important factor, especially on the Lufkin soils. The surface of the Lufkin soil seals over under high rainfall intensities and slows down the infiltration rate. This causes large amounts of water to be lost as surface runoff. At lower intensities runoff may occur as a result of the low infiltration rate. The legume cropping systems increased the average yield of corn 24 to 86 percent above that... of continuous unfertilized corn at the A&M Plantation. Their use, however, could hardly be justified in view of the good yields obtained by fertilizing continuous corn with 60 pounds of nitrogen per acre each year. Legumes used for green manure consume large amounts of water in their growth. Where soil moisture is a limiting factor in plant growth, legumes will use some water that otherwise would be available for corn and cotton. This leaves the soil dry at planting time and the corn or cotton TABLE 19. YIELD OF CORN IN CROPPING SYSTEMS AT DENTON. 1950-55 _ Bushels per acre‘ Average p system _ ‘ 1950’ 1951 1952 1953 1954 1955 1950-55 1951-55‘ i tinuously 47.6 26.4 7.2 6.0 33.6 34.7 25.8 21.6 Austrian Winter f 49.1 25.6 7.9 7.8 32.9 40.1 26.2 22.8 Dixie Wonder 47.2 20.8 5.1 5.6 31.0 35.7 23.7 19.6 '- Hubam sweetclover on manure 57.4 30.6 12.4 8.9 33.0 31.3 29.1 23.2 g~ Hubam sweetclover . 55.4 27.1 3.4 3.5 28.1 30.0 24.3 18.4 * Madrid sweetclover n manure 63.2 26.4 2.7 2.6 25.6 29.6 24.1 17.3 Madrid sweetclover l“, - 57.1 34.8 8.1 5.7 30.9 34.0 28.8 22.7 above treatments: - l 9.8 6.5 5.5 4.7 NS 6.1 NS 3.2 I l 13.5 8.6 7.4 6.4 NS 8.2 NS 4.9 l, yield for ’- a ‘ n‘ "~ 30.2 6.2 5.8 30.6 33.1 21.2 1» gen 24.6 7.1 5.6 30.7 34.0 20.4 F 2.4 NS NS NS NS NS 3.2 NS NS NS NS NS _ _- treatments were not made in 1950. a oi the 60-pound nitrogen treatment applied to all plots. l oi all treatments including nitrogen and no nitrogen for the cropping system. 1s’ must depend entirely on the soil moisture made available through rainfall during the growing season. With the planting dates used at College Station and Denton, June was the most critical period in the growth of corn. The effect of the green-manure crops on the chemical and physical properties of soil also should be considered. Chemical and physical studies were made in 1953-54 on the plots in the experiments on the Upland Farms at College Sta- tion. The legumes did not seem to influence materially the physical properties of the soil.‘ The plowing under of legumes, however, increased significantly the total nitrogen and nitrifying power of the soil.’ The legume plots also contained ‘Unpublished thesis entitled, “The Effect of Green Manur- ing with Winter Legumes on some Physical and Chemical Properties of Lufkin Fine Sandy Loam,” Sibte Mehdi N aqvi, submitted to the Graduate School of the A. & M. College of Texas in partial fulfillment of the degree of Master of Science, January 1954. “Unpublished thesis entitled, “Effect of Winter Annual Legumes on Certain Chemical Properties of Lufkin Fine Sandy Loam and on the Yield of Cotton,” Jose Dula- N avarrete, submitted to the Graduate‘ School of the A. & M"; College of Texas in partial fulfillment of the requirements for the degree of Master of Science, January 1955. 14 significantly more available phosphoric acid the plots receiving only fertilizer. Similar re . were obtained in other work conducted on v same soil type at College Station during 1937 ( 7) . LITERATURE} CITED 1. Fraps, G. S. and J. F. FudgefiChemical compositio soils of Texas. Texas Agr. Expt. Sta. Bill. 549. ' 2. Reynolds, E. B., G. T. McNess, R. A. Hall, P. R. J son, R. H. Stansel, Henry Dunlavy, P. B. Bunkle, H. F. Morris. Fertilizer experiments with c Texas Agr. Expt. Sta. Bul. 469. 1932. " 3. Reynolds, E. B. Winter legumes for Texas. '-: Agr. Expt. Sta. Progress Report No. 646. 1939. 4. Reynolds, E. B. Winter legumes as soil-improving c for cotton. Texas Agr. Expt. Sta. Progress NO. 716. 1941. , 5. Reynolds, E. B. and J. C. Smith. Vetch imp V‘ soil fertility in East Texas. Texas Agr. Expt. Progress Report No. 1024. 1946. " 6. Reynolds, E. B., P. R. Johnson and H. F. i; Hairy vetch, bur clover and oats as soil-building c_ for cotton and corn in Texas. Texas Agr. Expt. a Bul. 731. 1950. 7. Reynolds, E. B. and J . C. Smith. The effects of plo under hairy vetch on the yield of cotton on Lufkin , sandy loam. J our. Amer. Soc. of Agron. 38: 1 1946. [Blank Page in Original Bulletin] State-wide Research t. "z n’; "k The Texas Agricultural Experiment Station‘ is the public agricultural research agency of the State of Texas, and is one of ten parts oi the Texas A6=M College System Location oi field research units oi the Texas Agricultural Experiment Station and cooperating agencies ORGANIZATION OPERATION Research results are carried to Texas farmers, ranchmen and homemakers by county agents and specialists of the Texas Agricultural Ex- tension Service IN THE MAIN STATION, with headquarters at College Station, are 16 subject- a ,matter departments, 2 service departments, 3 regulatory services and the ? administrative staff. Located out in the major agricultural areas of Texas are 1 21 substations and 9 field laboratories. In addition, there are 14 cooperating. stations owned by other agencies. Cooperating agencies include the Texas? Forest Service, Game and Fish Commission of Texas, Texas Prison System, j U. S. Department of Agriculture, University of Texas, Texas Technological . College, Texas College of Arts and Industries and the King Ranch. Somei experiments are conducted on farms and ranches and in rural homes. THE TEXAS STATION is conducting about 4-00 active research projects, grouped .7 in 25 programs, which include all phases of agriculture in Texas. Amongf these are: Conservation and improvement of soil Beef cattle Conservation and use of water Dairy cattle Grasses and legumes Sheep and goats Grain crops Swine Cotton and other fiber crops Chickens and turkeys Vegetable crops Animal diseases and parasites Citrus and other subtropical fruits Fish and game Fruits and nuts Oil seed crops Farm and ranch engineering Farm and ranch business Ornamental plants Marketing agricultural products Brush and weeds _ Rural home economics Insects Rural agricultural economics Plant diseases Two additional programs are maintenance and upkeep, and central services. AGRICULTURAL RESEARCH seeks the WHATS, the WHYS, the WHENS, the WHERES and the HOWS ol hundreds of problems which confront operators of farms and ranches, and the many industries depending on or serving agriculture. Workers oi the Main Station and the field units oi the Texas Agricultural Experiment Station seek diligently to tind solutions to these problems. 306161” ,5 WQJQQPCL yd jOfVlOPPOl/Ull program/i