EXPERIREEINT STATES-II LEBRARY, BUILDING. A70-1 128-10,000-L18O TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 390 DECEMBER, 1928 DIVISION OF AGRONOMY EXPERIMENTS WITH FERTILIZERS 0N ROTATED AND NON-ROTATED CROPS AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATIONSTAFFT a E ~ - - ADMINISTRATION: VETERINARY SCIENCE: A B. CoNNEn, M. S., Director *M. FRANCIS, D. V. M., Chief R. E. KARPER, M. S., Vice-Director H. SCHMIDT, D. V. M., Veterinarian A, Sl-(IIHAEDEL, S‘eicret¢g,y_ f c, k F. E . CARROLL, D. V. M., Veterinarian 1. . . OLLEMAN, n, ie er L " J. K. FRANcKLow, Assistant Chief Clerk P JsglflmfggzlégllclgcghsgDCEg-YSIOLO s’. CHESTER I-lxccs, Executive Assistant W N EZFKIEL pf, D Pjant Pathologist C. B. EBLETTE, Technical Assistant ' Laboduow ‘Technl-Eian CHENHSTRY: . . W. J. BACH, M. S., Plant Pathologist G. S. FnAPs, Ph. D., Chief; State Chemist _]_ PAUL LUSK S M Plan, pathologist Iss- ‘ESBURY- SS» 145318111!" Chem“! B. F. DANA, ‘S., Plant Pathologist WALno HsLWELKERJAssLCsiTagtI Chemist FAIFM 4ND RANCH ECONOMICS: _ VELMA GRAHAM, Assistant Chemist - P~ (“Blsamh M- S-~ Chwf . 1 H. S. Oscoon, M. S., Assistant Chemist W- E- Péul-SON- Ph- D-v Market“? Ram" T. L. OGiEn, B. S , Assistant Chemist Spéclahst ' J. G. EVANS, Assistant Chemist C- A- ONNEN- M.- $-- Fan" Management ATHAN J. STERGES, B. S., Assistant Chemist v LRgeamh Speclall-‘t . ' G. S. CRENSHAW, A. B., Assistant Chemist ' - ORY- M- 5'» Gran"? Research Ba‘ JEANNE M_ FUEGAS Assistant chemist J. F. CRISWELL, B. S., Assistant; Farm Reco »_ ‘ and Accounts Hgés-llisclgifgislsgggs’ M‘ Se" Assistant Chemist "J. N. TATE, B. S., Assistant; Ranch Recof HAMILTON P. TnAuE, Ph. D., Chief and Acaaums H. NEss, M. S., Berry Breeder RURAL HOME RESEARCH: RANGE ANIMAL HUSBANDRY: JEssiE WHITACRE, Ph. D., Chief J. M. JoNEs, A. M., Chief; Sheep and Goat Investigations J. L. LUSH, Ph. D., Animal Husbandman; Breeding Investigations STANLEY P. DAVIS, Wool Grader E1%TOMOLOGY' W. T. CARTER, B. S., Chief E. H. TEMPLIN, B. S., Soil Surveyor L. THOMAS: Ph. D., Chief; State T. C. BErrcn. B. S., Soil Surveyor H JElgggtqggfllSl B S E t ologist BéJItEQ$AGsDALE, B. S., Soil Surveyor . . no, . ., n om : R. K. FLETcnEn, M. A., Entomologist H. NEss, M. S., Chief EV. L. OKXEIEI, Jn., SS, gnitomollogistt svgxliécfiw rlglbgigaklizii.) S., Botanist RANK . ULL, . ., n omo ogis : A . . onn, . ., n omo ogis : _ F. F. BIBBY, B. S., Entomologist O. C. COPELAND, B. ., Dairy Husbandman .. S. E. MCGREGOR, Jn., Acting Chief Foulbrood POULTRY HUSBANDRY: f Ins ector _ ' R. M. SHERWOOD, M. S., hief A€%%IO£IF§WE MAcKEY, M. S., Associate Professor of Animal Husbandry Moeronn, M. S., Associate Professor of Agronomy H TA: of December 1, 1928. "Dean, School of Veterinary Medicine. "In cooperation with U. S. Department of Agriculture. "aln cooperation with the School of Agriculture. SYNOPSIS This is a report 0f experiments conducted over a period of 14 years to study the effect of fertilizers, manure, removal. 0f crop residues, and rota- tion 0n the yield of crops. The fertilizer treatments included superphos- phate; superphosphate and manure; superphosphate and cottonseed meal; manure; rock phosphate; and rock phosphate and manure. Cotton and corn were grown continuously on the same land and in rotation with oats and cowpeas. The soil responded more readily to nitrogenous than to phosphatic fer- tilizers, indicating a deficiency of nitrogen. The increases in yield, how- ever, resulting from the fertilizer treatments were not in general very profit- able. Manure was the most profitable treatment on cotton, giving an average yearly profit of $6.36 per acre. None of the fertilizer treatments applied to corn were very profitable; rock phosphate gave the largest profit, which was only 88 cents per acre a year. Superphosphate and rock phosphate were equally effective in increasing yields, but the rock phosphate was the more profitable because it was less expensive than superphosphate. The removal of crop residues over a period of 14 years has produced a slight, but not significant, decline in the productiveness of the soil. It is probable, however, that if the practice of removing the residues is con- tinued over a much longer period a significant reduction in yield will occur. Rotation produced significant increases in the yield of cotton and corn. The yield of cotton was increased 14 per cent and the yield of corn 47.5 per cent in comparison with the yield of continuous cotton and corn, re- spectively. Rotation produced larger increases in yield than fertilizer, but the largest yields were obtained where rotation and fertilizer were used together. In fact, the increase in yield resulting from the combined use of rotation and fertilizer was greater than the sum of the increases pro- duced by rotation and fertilizer when used separately. Although rotation increased the yield of cotton and corn, the average acre value of the crops grown in rotation was less than the acre value of continuous cotton. The particular rotation of cotton, cowpeas, corn, and oats, therefore, was not profitable in comparison with continuous cotton, largely on account of the low acre value of cowpeas and oats. A two-year rotation of cotton and suitable feed crops should be satisfactory. Since it is good business to produce the feed required, on the farm and since rotation increases the yield of crops, it follows that the crops grown should be included in a rotation. It is clear, therefore, that a rotation costs the farmer nothing provided he uses the most suitable crops for his purpose, and thfeiat larger yields resulting from the rotation represent so much gain or pro . CONTENTS PAGE Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 Plan of Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Size of Plats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 Fertilizer Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 Plowing the Land. . . . s,» . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Time and Method of Applying Fertilizers . . . . . . . . . . . . . . . . .. 9' t‘ Disposal of Crop Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 Influence of Rainfall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 Effect of Fertilizer on Yield of Crops . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11 Yield of Cotton in Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Yield of Continuous Cotton . . . . . . . . . . . . . . . . . . . . . . . . .. 15 Comparison of Rotated and Continuous Cotton . . . . . . . . .. 18 Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19 Yield of Corn in Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . .. 20 Yield of Continuous Corn . . . . . . . . . . . . . . . . . . . . . . . . . . .. 23 Comparison of Rotated and Continuous Corn . . . . . . . . . . .. 25 Yield of Oats in Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27 Yield of Cowpeas in Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 29 Discussion of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Efliect of Rotation on Yield of Crops . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 31 Corn . . . . . . . . . . . . . . . . . . .9 . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . 33 The Value of Crops in Rotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Summary .~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . 39 BULLETIN NO. 390 DECEMBER, 1928 EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS E. B. REYNOLDS In 1914 the Division of Agronomy, Texas Agricultural Experiment Station, began field experiments to study the effects of fertilizers, manures, green manures, and rotation of crops on the yield and other characters of crops. These experiments have been conducted at the Main Station, College Station, and at the substations in the different parts of the State. The main objects of the experiments conducted at College Station were to determine the effects of fertilizers, manure, removal of crop residues (such as corn stalks, cotton stalks), and rota- tion on yield of crops. In this Bulletin are reported the results obtained at College Station with cotton, corn, oats, and cowpeas, for the 14 years, 1914 to 1927. The field experiments at the Main Station, College Station, have been conducted on Lufkin fine sandy loam soil. The surface soils of the Lufkin series are gray to ashy gray in color, while the subsoils are gray or mottled grayish and yellowish, and range in texture from compact sand to impervious, plastic clay. The topography is either fiat, un- dulating or rolling, and this, together with the impervious nature of the subsoil, results in poor drainage both on the surface and through the soil. The poor drainage through the soil is perhaps the most character- istic feature of the Lufkin soils. Some of these soils, particularly in Brazos county, have fairly good surface drainage. The Lufkin soils are low in organic matter and. nitrogen. In the virgin state these soils are forested, the heavier types mainly with" post oak, and the more sandy types with pine and mixed hardwood. The Lufkin soils are developed more or less extensively in east-central Texas, in the western part of the section sometimes called the “flat-woods.” They occur in Angelina, Polk, Houston, Trinity, San J acinto, Walker, Montgomery, Madison, Brazos, and Grimes counties. While the Lufkin soils occur rather ex- tensively in these counties, other soils, such as the Ruston and Norfolk, also occur. The results of the fertilizer experiments on the Lufkin fine sandy loam should be applicable generally to the Lufkin soils of the re ion. g PLAN OF THE EXPERIMENT The field work consists of a four-year rotation of cotton, cowpeas, corn, and oats followed by cowpeas as a catch crop, and continuous cotton and continuous corn. Six blocks of land, each consisting of 10 one-tenth acre plats, exclusive of border or guard rows, are used. The blocks of land are designated as B, C, D, E, F, and G (Table 1). Block B has grown corn and Block G has grown cotton, every year. N 0 I T A T S T N E M 2|. R E P x E L A R U T L U 0 I R G A S A X E T 0 9 3 0 N N I T E L L U B 6 3R25m523325w 3R255225555m 3R25523325m 3R25w325:055m 02R525523055m 3R225523325w R05 2.0050250 R05 50502200 R05 2.0050550 R3: 200050300 R05 250505200 255: 2000502200 2 20022050: 5525mm 252,050: w05225m 2.02553 ww522w0m 2.022050: 552022622 252,053 m0522w0m 2002550: 552025m N 2555532 072 2505532 072 505532 072 50525532 072 505532 072 53:50.5 072 m 3R25523325m 35255252o55w 3R225525:v.25m o2R25525h55m 3R255223055m 3R25522P2055m “w 0.5532 0.5:R22 95:32 05:32 05:32 0.5552 m 555252.532 072 55055.32 072 2535R0b 072 2505532 072 505553 072 2505532 072 o 3R255223055w 35525052255055 BR2252522222325 3R255225555w 32525522525250 352.252.25.855 25R 05:32 25R 35:32 25R 35:52 25R 0252522 25R 0.5552 25R 35:R2>2 h 325255225 25m 025255225 25m 525255225 25m 025255225 25m 525255225 25m 5252555222 25m w 3555: 25R 355.5: 25R 3555: 25R 3555: 25R 35:5: 25R 0.555.: 25R 525222.525 25m 5252525225 200m 5225525525 25m 355222.552: 25m 3.25.2525 25m 35255225 200m m 2505532 072 2552R32 072 25555.5 072 25052532 072 53:50.52 072 505532 072 o2 2R9» >550 55D mm-w2|2la2 3R0 mw|w2|22m2 :02.20U mm-wTuw2a2 532500 mm-w2|2~2m2 550 2R9» >525 50250 .072 m 252m U 252m m 252m m 252m 5 252m U 252m RE .53:2:3220 5052222202 :2 25R2 .20 @2522 25R 8.5.2 .20 5o50w53:<|..2 QERH EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 7 The four-year rotation of cotton, cowpeas, corn, and oats occupies Blocks C, D, E, and F. Cotton occupied Block D in 1914, Block C in 1915, Block F in 1916, BlockE in 1917, and in 1918, the fifth year of the rotation, cotton again occupied Block D. The other crops followed in regular order. Size of Plats The plats consist of 13 rows, each row being 3 feet wide and 132 feet long. The first row and the last row of each plat serve as border or guard rows, which are discarded at harvest time. These guard rows are used to prevent the treatment on one plat from affecting the yield on adjacent plats. The area harvested on each plat, therefore, consists of 11 rows, or one-tenth acre. Fertilizer Treatments The fertilizer treatments of the experiment, as originally outlined and as conducted until 1922, are shown below. These treatments were applied to crops grown in rotation. Plat No. Treatment Per Acre 1 200 pounds superphosphate* and 100 pounds cottonseed meal 2 Crop residues removed 3 No treatment—check 4 200 pounds superphosphate 5 5 tons manure (applied to cotton only) 6 N0 treatment—check. 7 5 tons manure and _ 200 pounds superphosphate (applied to cotton only) 8 Ground rock phosphate equal to the amount of phosphoric acid in 200 pounds of superphosphate 9 5 tons manure and _ _ _ ground rock phosphate e ual to the amount of phosphoric acid in 200 pounds of superphosphate (app ied to cotton only) 10 No treatment—check *Superphp_sphate is the same as acid phosphate. The term superphosphate has been adopted by the fertilizer industry. The above treatments were applied also to the continuous cotton and corn, except that the treatments of-rock phosphate and manure were omitted entirely and the treatment of manure and superphosphate was not applied to the same plat each year; the first year it was on plat 5, the second year on plat 7, the third year on plat 8, the fourth year on plat 9, and the fifth year on plat 5 again. Since all of the treatments of the rotated and continuous crops were not comparable, as pointed out above, the plan of the experiment was changed in 1922 so as to make the treatments on all the blocks uniform. 8 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION That is, the treatment of Plat 1 on Blocks B, C, D, E, F, and G would be the same; the treatments on Plat 2 of all six blocks would be the same; u and the other plats were treated in a similar manner as shown in Table Z_ 1. The revised plan in detail is shown below and the treatments shown a are applied to each of the six blocks every year. Plat No. Treatment Per Acre 1 200 pounds superphos hate and 100 pounds cottonsee meal Crop residues removed No treatment——check 200 pounds superphosphate 4 tons manure No treatment—check QOQUPWM 4 tons manure and 200 pounds superphosphate 8 Ground rock phosphate equal to the amount of phosphorus in 200 pounds of superphosphate 9 4 tons manure and Ground rock phosphate equal to the amount of phosphorus in 200 pounds of superphosphate 10 No treatment—check It will be noted that the only difference between the old plan and the revised plan is that all of the treatments are applied to each crop every year, that rock phosphate is applied also to the non-rotated cotton and corn, and that the manure is applied at the rate of 4 tons per acre every year instead of 5 tons every four years. This treatment of manure thus supplies 16 tons of manure every four years instead of 5 tons, or more than three times as much as furnished by the original plan. It should be pointed out that 107 pounds of the ground rock phos- phate used contained the same amount of phosphorus as the 200 pounds of 16 per cent superphosphate. In the following tables reporting the yields of the crops, the amount of rock phosphate is given as 107 pounds rather than rock phosphate equal to 200 pounds of superphosphate. Plowing the Land In the earlier years of the experiment, plowing was done across the blocks, each plat being plowed as a unit, with a back furrow in the center to provide good surface drainage. This method of plowing soon provided the necessary drainage. After adequate drainage was provided on the plats, plowing was done across the plats either with a two-way plow, turning the furrow slice in one direction or with a single mold- board plow dragging around the ends, to avoid turning Within the experi- mental area. 3 EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 9 Time and Method of Applying Fertilizer and Manure The time and method of applying the fertilizer materials has been rather variable. During the first years of the experiment the fertilizer was applied along the row with a fertilizer distributor at planting time or two or three weeks after planting in the case of cotton, corn, and cowpeas. From 1922 to 1927, inclusive, the fertilizers were applied broadcast two or three weeks before planting. The materials have been applied broadcast to the oats. The manure ' has always been applied before planting and disked into the surface soil. Previous to 1922 the fertilizer was applied broadcast early in the spring to the fall-planted oats. Since 1922 the fertilizers have been applied to the land before planting the oats. Disposal of Crop Residues On Plat 2 of all six blocks the crop residues have been removed after harvesting the corn, cotton, and cowpeas and before plowing the land for succeeding crops. The oat stubble has not been removed. The oat- stubble land, however, was plowed as soon as practicable after harvest T and the land seeded to cowpeas as a catch crop for soil improvement. Influence of Rainfall The average rainfall at different places in the region, as published ‘f by the United States Weather Bureau, “Climatological Data: Texas E Section,” is given here. ‘J Av_era e j Station County Rainfa l, E Number l. Inches of Years g‘ Collegefitation . . . . . . . . . . . . . . . . . Brazos . . . . . . . . . . . . . . . . . . . . . . 38.21 38 .Hunt_sv1lle . . . . . . . . . . . . . . . . . . . . . Walker . . . . . . . . . . . . . . . . . . . . . . 42.94 44 5z 5.5.5 5H“.5 HNN N5.HH 5N.5 N55 N5.H 5H.5 55.5 5H5 NH. 5 5H.5 55.H 55.5 Ed . . . . . . . . . . . . . . . . . . . . . ..§H85o 55.H H56 H5.5 N55 55.H H“5.H“ N5 H 55.5 55.5 5N5 H5.5 55N H5.5 5H“.5 >55 . . . . . . . . . . . . . . . . . . ..H2HE8555 5N5 N5.5 N5.H H“5N NH.5 N5 H 555 5N.5 5H; HH“.5 5N.H 5H“.N 55.5 55.5H 5H.» . . . . . . . . . . . . . . . . . . . . . 135554 55H $5 5H.5 NH H 5N H N5 N 55.5 H“5 5 H“5.H“ SH“ $5 55.5 55 H 55.5 5H“ 5 . . . . . . . . . . . . . . . . . . . . . . . . 12:5 5H“.5 H5 5 55.5 55H 5N H 55.5 55.H“ 55 5H 55.5 H5.5 55N 55.5 H“5 N 55.5 NH 5 . . . . . . . . . . . . . . . . . . . . . . . . .5555 55.H“ 55H H5H“ N55 5H 5 55 5 H5.5 55 H 55.5 5N5 N5N 55H 55.HH 55.5 3.5 . . . . . . . . . . . . . . . . . . . . . . . . 1552 5N.5 55 5 5.“. H“ 55.H NN.5 H5.H“ 5N8 55 NH 55.5 N5 H 5:“ HR N 55.5 55 5H 55.N . . . . . . . . . . . . . . . . . . . . . . . 1555.5 H“5N 55.N 55.5 55.5 55N 555 55.5 5H H“ 5H“.H 55N N5.5 5H“.5 55 5 55H 5H“.5 . . . . . . . . . . . . . . . . . . . . . . ..HH85H>H .N 5N.5 HN.5 N5.5 H55 55H“ 5H.H“ 55.H 55.5 55.5 55.H“ HN.N 55.5 555 55N . . . . . . . . . . . . . . . . . . . . . ..D5HEH5~H 5N.5 55.H 5H“ NNH H“N H“ 5N 5 55.5 55.N 55.5 NH H“ 55H 55H 55.5 55.N .55 . . . . . . . . . . . . . . . . . . . . . .5§HHH£. H5 5 55.5 55 5 55.5 5H.5 55H“ NH.5 HRHH NN5H 5H“.5H 55H“ 55.5 55.5 NH“.NH $.35 H5=5HH< H55 5H5, .255 S5 135B 55.55 5N.HH“ 55.5“ NH“.H5 55.55 25H“ 55.5H“ 5N.5H“ 55.5“ 55.55 55.H“5 55.5H 55.5N N5.5H“ N555 . . . . . . . . . . . . . . . . . . . . . . . 155a 558525 NN5H 5N5H 5N5H H“N5H 5N5H NN5H HN5H 5N5H 5H5H 5H5H 25H 5H5H 5H5H H“H5H 5252 535355 Kmmfi o5 Hi2 dofimum 555525 Himiwwww wcvfiiwmxm 0H3 5N 5on2: E zficfimlum 535M. N m T A T S T N E M I R E P X E L A R U 5 U >5 w R G A S A X E T O, 9 3 O. N N I T E L L U B 10 EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 11 EFFECT OF FERTILIZERS ON YIELD OF CROPS The effect of fertilizers on the yield of each crop is discussed sep- arately. The yield of crops grown in rotation and the yield of crops grown continuously on the same land are also considered separately. Then the results of the two systems of cropping are brought together and compared directly. Cotton» The experiment included cotton grown in rotation and cotton grown on the same land every year. In any year the same variety of cotton was used in both systems of cropping. The same variety, however, was nottused every year of the experiment. The Hendricks variety was planted in 1916, while Lone Star or strains of Lone Star have been grown in the test since 1916. The spacing of cotton has varied some- what during the experiment, but for any year the spacing was the same for both rotated and continuous cotton. In most years the spacing was p one plant every 12 inches in the row, but in 1923 the spacing was 18 ‘inches. The spacing of 12 inches in rows 3 feet apart provides 14,520 plants per acre. The rotated cotton was a failure in 1920, due pri- marily to late germination of the seed, and, as a consequence, the cotton failed to mature before frost. Yield of Cotton in Rotation The results secured with rotated cotton are presented in Table 3. Only five of the treatments occurred every year of the experiment. Of these five treatments, the application of 4 tons of manure and 200 pounds superphosphate* made the highest average yield, 204 pounds of lint per acre for the 14 years. The treatment of 4 tons of manure made about as large yield, 201 pounds per acre. For the 13 years, 1914 to 1927, omitting 1920, the treatment of cottonseed meal with superphosphate produced an average yield of 205 pounds of lint; manure with superphosphate, 220 pounds; and the p manure alone, 216ipounds of lint per acre. These were the only treat- ments that produced yields significantly greater than the yield of the " plats which received no treatment, according to Student’s method. As pointed out in Table 4, the chances, or odds, are 105.9 to 1 that the difference in the yield produced by the treatment of manure and super- iphosphate and the yield produced by the untreated plats is significant. ‘ Usually it is considered that the odds must be 22 or more to 1 to indi- cate a significant difference. It seems certain, therefore, that this differ- ence in yield is due to the treatment and not to chance or difference in soil. ‘ w, ",vr‘,m,.,,..,. . - ‘Previous to 1922 this treatment consisted of 5 tons of manure and 200 pounds of superphosphate and was applied to cotton only, the other crops in the rotation receiv- g the residual effect. Since 1922 the treatment has been 4 tons of manure a.nd 200 unds of superphosphate and has been applied to each of the four crops in the rotation. 12 BULLETIN N0. 39o, TEXAS AGRICULTURAL EXPERIMENT STATION 6N2 MGSQMEQV: _NN . . . . . . . . . . .. N 2 NNN N2 NNN N2 NNN N2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2252. 2:: N owmnnmcsn xooh N5 >2 2N .. . . . . .. N2 NNN 32 SN N2 NNN N2 NNN . . . . . . NN . . . . . . . . . . . . . . . . . . . .. 2222325.» N2: .2: .2: NNN NNN SN 2N NNN N2 NNN SN NNN N3 NNN NN NN NNN NNN 2N zémaNwonNhwNi .2: NNN @2585 Ncoa w» NNN 2N SN 2N Nwm NNN NNN NNN NNN 3N3 3N NN NN NNN NNN NNN . . . . . . . . . .2255 2.8 N NNN N2 N2 N2 NNN SN 2N NNN NNN N2 5N E NN NNN NNN SN {BNNNNNNNENNE .2: 8N NNN N2 N2 .23 2N N2 5N 2N NNN NS SN NN NN 2N NNN NNN .. . . NRENIENENNN: oz N2 N2 N2 NS NNN SN m3 N2 NNN NN N2 E NN 2N 2N NNN . . 622.82 NNNENN: N20 2N NNN 22 N2 NNN NNN SN NNN NNN N: 3N NS NN NNN NNN SN . . NNNNNNQNNHNNE .2: NNN _ 13E wowmsofioo in: OOH .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 .23 E2 iN2 NN2 .53 NN2 NN2 3&3 NN2 NN2 3N2 22 22 22 22 £2 32 N54 6m E2262 |NN2 132 1E2 325822.32 23522.2 oww$>< 304 Sm ~54 Mo $250k E 32> SZNEQE §mm~ 3 32 aofifiw wmw=oU 3N uflwa-SMQQNQ gunman-h.“ E uoghoo 2.3.x?“ No Hzotrlkm 03mm. duced by superphosphate and rock phosphate. EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 13 The data in Table 3 show there was little difierence in the yields pro- The yields of these treat- gments were not significantly greater than the yield of the plats which freceived no treatment, during the siX years, 1922 to 1927, inclusive. i All o1": the treatments except superphosphate and the untreated check .174 pounds of lint per acre and the plats with ‘ ilats made significantly larger yields than the plats from which the crop ._residues were removed. The check plats produced an average yield of the residues removed ,produced 163 pounds per acre for the 14 years. While this is a diifer- _.ence of 11 pounds per acre a year, 1 {shown by the odds in Table 4. Table 4.—-—Comparison by Student's method t is not statistically significant, as of_ yields of rotated cotton treated with different ‘f Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . rt1 zers. N0. of _ Years Greater Yield Smaller Yield Odds Treatments Were Compared jCottonseed meal and superphosphate. No treatment . . . . . . . . . . . . . . . . 35.8 : 1 13 No treatment . . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 4.3 : 1 13 Superphosphate . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 3.5 : 1 13 . anure . . . . . . . . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 65.0 : 1 13 _ anure and superphosphate. . . . . . . . . No treatment . . . . . . . . . . . . . . . . 105.9 : 1 13 .= ' ock phosphate . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 2.9 : 1 9 > ' ock phosphate and manure . . . . . . . . No treatment . . . . . . . . . . . . . . . . 2.9 : 1 7 Cottonseed meal and superphosphate. Crop residues removed . . . . . . . . 210.0 : 1 13 f ttonseed meal and superphosphate. Superphosphate . . . . . . . . . . . . . . 17.7 : 1 13 anure and superphosphate . . . . . . . .. Cottonseed meal and super- phosphate . . . . . . . . . . . . . . . . . 5.7 : 1 13 Cottonseed meal and superphosphate. Rock phosphate . . . . . . . . . . . . . . 1.0 : 1 9 JRock phosphate and manure . . . . . . . . Cottonseed meal and super- ;' phosphate . . . . . . . . . . . . . . . . . 1 .0 : 1 7 ..- Manure. . . . ., . . . . . . . . . . . . . . . . . . . . .. Cottonseed meal and super- phosphate . . . . . . . . . . . . . . . . . 33.7 : 1 13 . Superphosphate . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 5.5 : 1 13 . Manure and superphosphate . . . . . . . . Crop residues removed . . . . . . . . 78.5 : 1 13 f‘ Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 66.2 : 1 13 , Rock phosphate . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 34.4 : 1 9 ‘ Rock phosphate and manure . . . . . . . . Crop residues removed . . . . . . . . 16.6 : 1 7 iTVIanure . . . . . . . . . . . . . . . . . . . . . . . . . '. . Superphosphate . . . . . . . . . . . . . . 37.2 : 1 13 Manure and superphosphate . . . . . . . . . Superphosphate . . . . . . . . . . . . . . 42.4 : 1 13 ‘j Rock phosphate . . . . . . . . . . . . . . . . . . .. Superphosphate . . . . . . . . . . . . . . 1.9 : 1 9 i Rock phosphate and manure . . . . . . . . Superphosphate . . . . . . . . . . . . . . 2.7 : 1 7 ,;Manure and superphosphate . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 14.7 : 1 9 , Manure and superphosphate . . . . . . . . . Rock phosphate and manure. . . 7 .5 : 1 7 ;_Rock phosphate and manure . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 4.8 : 1 6 liManure . . . . . . . . . . . . . . . . . . . . . . . . . . . Rock phosphate and manure. . . 19 .9 : 1 6 ; Manure and superphosphate . . . . . . . . . Manure . . . . . . . . . . . . . . . . . . . . . 1.0 : 1 13 Rock phosphate . . . . . . . . . . . . . . 42.5 : 1 9 The treatment of 4 tons of manure made the highest average yield, .268 pounds of lint per acre, for the six years, 1922 to 1927. Manure with superphosphate ranked second, with an average yield of 255 pounds G1‘ acre. This, small difierence in yield is not significant. manure, however, was the most profitable treatment, as will be shown The 14 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION later.‘ The manure alone made significantly larger yields than th' treatment of cottonseed meal and superphosphate. i The results in Table 3 show that manure alone was the best treatmen i‘; used. The results also show that nitrogen in the form of manure pro duced larger yields than phosphoric acid, either in the form of super-f phosphate or rock phosphate. This is confirmed further by the fac that the addition of superphosphate to the manure or superphosphate with cottonseed meal did not produce larger yields than the manure. alone. Apparently the soil did not respond readily to applications of i phosphoric acid as indicated by the yields of rotated cotton. , In the preceding paragraphs the fertilizer treatments were discussed in relation to yield. It is desirable to know also the profits or lossesj that may be expected from the use of fertilizers. Accordingly, the profits and losses resulting from the fertilizer treatments used were ’ computed. The losses or gains produced by the treatments were deter- mined by subtracting the cost of the fertilizer from the value of the l’ increase produced by the treatment. T The prices of cottonseed meal and superphosphate were taken from ‘l Texas Station Bulletins 298, 312, 322, 335, 346, and 368. The manure .- was figured at $1.25 a ton. Rock phosphate is usually not sold on the retail market and for this reason retail prices are not available. Some‘ A rock phosphate, however, was bought at $12.00 a ton in 1925 and this price was used in calculating the profit or loss resulting from rock phosphate. The estimated price of cotton for December 1 of each year. as given in the year books of the United States Department of Agricul- 7. ture were used in computing the value of the cotton. Table 5 gives the _. profits or losses resulting from the different fertilizer treatments during l the six years, 1922 to 1927, inclusive. Table 5.-—-Profit or loss per acre attributable to different fertilizer treatments applied to < cotton 1n rotation. Fertilizer Treatment 1 922 1 923 1 924 1 925 1 926 1 927 Average Dollars Dollars Dollars Dollars Dollars Dollars Dollars _ 100 lbs. cottonseed meal ' l 200 lbs. superphosphate . . -4.88 -0.48 -4.40 3.46 -1.29 3.82 —0.63 Crop residues removed. . . —5.41 -4.26 —12.10 1.11 2.48 -0.77 —3.16 200 lbs. superphosphate.. . —2.32 -2.34 —2.30 -0.68 0.99 -2.12 —l .46 4 tons manure . . . . . . . . . .. -—4.76 22.06 7.54 ~0.37 6.02 13.14 7.27 ‘i’ 4 tons manure ‘Z00 lbs. superphosphate... . —3 .56 34.61 —7 .30 —7 .35 —2. .07 12. .18 4.42 107 lbs. rock phosphate . . 7.10 -0.65 -0.65 -0.65 4.64 7.46 2.87 107 lbs. rock phosphate 4; tons manure . . . . . . . . . . . 2.34 -5 . 65 —5.65 -5 .65 1.05 6.32 -1.21 l The application of 4 tons of manure made an average profit of $7.27 p per acre, and was the most profitable treatment used. Manure with EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 15 superphosphate was the next most profitable treatment, producing an average yearly profit of $4.42 per acre. Rock phosphate at the rate of 107 pounds per acre (equivalent t0 the phosphoric acid in 200 pounds of 16 per cent superphosphate) made a profit of $2.87 per acre, as com- pared with an average loss of $1.46 per acre for superphosphate. The other treatments were used at losses ranging from $0.63 to $3.16 per acre. Yield of Continuous Cotton The yields of cotton grown on the same land every year, that is, con- tinuous cotton, are shown in Table 6. Yields were obtained from only five of the eight treatments every year, since the treatments of manure alone, rock phosphate, and manure and rock phosphate began in 1922. The application of 200 pounds of superphosphate made the highest average yield, 193 pounds of lint per acre, for the 14 years of the experi- ment. The treatments of cottonseed meal with superphosphate and manure _with superphosphate ranked next with an average yield of 182 and 180 pounds of lint per acre, respectively, for the 14 years, and the same average yield, 181 pounds, for the 13 years. There were no sig- nificant differences in the yield of these three treatments as shown by the odds in Table 7. The yields of these treatments were significantly greater than the yield of the check plats which received no treatment and were also greater than the yield of the plats from which the residues were removed. The plats with the crop residues removed made an average yearly yield of 157 pounds, of lint per acre for the 14 years and the check plats which received no treatment made an average yearly yield of 161 pounds. This slight difference in yield was not significant, as shown in Table 7, indicating that the removal of crop residues for a period of 14 years did not produce a significant decline in the pro- ductiveness of the soil. In fact, for the last six years the average yields were practically identical, being 176 and 177 pounds per acre, re- spectively. The superphosphate made an average yield of 207 pounds of lint per acre and the rock phosphate made 212 pounds for the six years, 1922 to 1927, inclusive. The difierence in yield was not significant as shown by the odds in Table 7. During the six years, 1922 to 1927, the manure alone produced the highest average yield, 225 pounds of lint per acre. This yield was sig- nificantly greater than the yield of 206 pounds made by the manure and superphosphate. It was the best and one of the most profitable treatments used, as was also the case with the rotated cotton. The profits resulting from the fertilizer treatments applied to cotton grown on the same land every year during the six years, 1922 to 1927, are shown in Table 8. The profits or losses in this table were deter- mined by subtracting the cost of the fertilizer treatment from the value. of the increase produced by the treatment. N m T A T S T N E M I R E P x E L A R U T L U C TL R G A S A x E T 0 9 3 O N N I T E L L U B 16 6N2 “E2569, woN . . . . .. a2 mom av vmN ovN m2 .. . . . . . .. . . . . . . . . . . . .. .. . .9E%%wfia¢no~w a $23 xuou i: >2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .QMNSQ |mO£Q.v~OO.~ .2: >2 woN 22 62 . w2 3m F. 3N vmN moN m2 >2 m2 mm 2N mNN m2 8m . . . . .32.“ - onauonsw d5 ooN 0.22222 mac“ w mNN ............NoN >wm ow 2N wwN 2N .. .. . .. . . . . ......v.5:wEwno¢¢ >oN a: .22 o2 mNm >m NNN 8N mmN w: N>N 22 m> fi, 2m 2N >wN . . . . . . 68am . Lmonnhonsm .2: ooN >2 wfi 22 m2 wwN mm m2 NmN $2 m2 2N E2 ww 3 2N m2 >mN . . . . . . 52$ Ififinfiwob oZ w: 3; >2 N2 wwN >m o2 wwN m2 om N2 m. w> >m \ 5N woN wwN . . . . . 602.5 L3 monwmwou Q80 2N 22 N2 m2 5m .6 NmN 8N 5N o2 m2 mm mw Nm >mN 3N Now . . . . . . 6222a . . aofirofi.» .9: ooN 13E uoomqofioo d“: o2 .23 .25 .23 .23 .2: .22 .2: .23 .2: .2: AAA .22 .312 .23 .54 .22 .25 >N2 *>N2 >N2 |NN2 L22 l22 >N2 wN2 mN2 2N2 mN2 NN2 2N2 oN2 22 22 >22 22 22 22 I maqozimohn. ponmihoh omm~o>< .83 5m E3 a. 2.5.8 E 22> dZwEQE .>N2 3 22 dowfim owozoU G unofitoano kwuzfihow E nofioo wnoscfiaoo mo E2 F.1d 03am. EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 17 Table 7.—Comparison by Student’s method of yields of continuous cotton treated with different fertilizers. _ No. of _ Years Greater Yield Smaller Yield Odds Treatments ere Compared Cottonseed meal and superphosphate. No treatment . . . . . . . . . . . . . . . . 47.9 : 1 14 No treatment . . . . . . . . . . . . . . . . . . . . . . Crop residues removed._ . . . . . . . 4.0 : 1 14 Superphosphate . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 385.8 : 1 14 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . N0 treatment . . . . . . . . . . . . . . . . 118.5 : 1 6 Manure and superphosphate . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 38.7 : 1 14 Rock phosphate . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 19. 1 z 1 6 Rock phosphate and manure . . . . . . . . No treatment . . . . . . . . . . . . . . . . 37. 1 : 1 6 Cottonseed meal and superphosphate. Crop residues removed . . . . . . . . 123.1 : 1 14 Superphosphate . . . . . . . . . . . . . . . . . . .. Cottonseed meal and super- phosphate . . . . . . . . . . . . . . . . . 5.0 : 1 14 Manure . . . . . . . . . . . . . . . . . . . . . . . . . .. Cottonseed meal and super- phosphate . . . . . . . . . . . . . . . . . 7.7 : 1 6 Cottonseed meal and superphosphate. Manure and superphosphate. . . 1.0 : 1 14 Cottonseed meal and superphosphate. Rock phosphate . . . . . . . . . . . . . . 3.2 : 1 6 Cottonseed meal and superphosphate. Manure and rock phosphate. . . 14.6 : 1 6 Superphosphate . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 177.7 -: ~1 ‘ 14 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 51.7 : 1 6 Manure and superphosphate . . . . . . . . . Crop residues removed . . . . . . . . 43.2 : 1 14 Rock phosphate . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 10.7 z 1 6 Rock phosphate and manure . . . . . . . . Crop residues removed . . . . . . . . 15.4 : 1 6 Manure . . . . . . . . . . . . . . . . . . . . . . . . . .. Superphosphate . . . . . . . . . . . . .. 9.2 : 1 6 Superphosphate . . . . . . . . . . . . . . . . . . . . Manure and superphosphate. . . 6.6 : 1 14 Rock phosphate . . . . . . . . . . . . . . . . . . . . Superphosphate . . . . . . . . . . . . . . 2.0 : 1 6 Superphosphate . . . . . . . . . . . . . . . . . . . . Rock phosphate and manure.. . 1.0 : 1 6 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Manure and superphosphate. . . 75.5 : 1 6 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 15.8 z 1 6 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Manure and rock phosphate. . . 18.6 : 1 6 Rock phosphate . . . . . . . . . . . . . . . . . . . Manure and superphosphate. . . 2.9 : 1 6 Rock phosphate and manure . . . . . . . . Manure and superphosphate. . . 1 .0 : 1 6 Rock phosphate . . . . . . . . . . . . . . . . . . . Rock phosphate and manure. . . 2. 1 : 1 6 Table 8.—Profit or loss per acre attributable to different fertilizer treatments applied to continuous cotton. Fertilizer Treatment 1922 1923 1924 1925 1926 1927 Average Dollars Dollars Dollars Dollars Dollars Dollars Dollars 100 lbs. cottonseed meal 200 lbs. superphosphate.. . 8.52 —2.61 5.46 -3.02 6.27 2.08 2.78 Crop residues removed. . . —4.47 10.94 —2.69 0.74 0.00 —3.09 0.24 200 lbs. superphosphate.. . 19.07 -1 .12 5.32 -1.61 1.53 0.20 3.90 4tons manure . . . . . . . . . .. 12.63 5.94 1.27 3.70 5.69 3.49 5.45 4 tons manure 200 lbs. superphosphate.. . 7 .02 —6.73 -3.72 -7.35 —0.99 0.60 -1 .86 107 lbs. rock phosphate. .. 18.62 -0.65 5.62 —0.65 9. 18 2.82 5.82 107 lbs. rock phosphate 4 tons manure . . . . . . . . . .. —-0.48 —3.22 4.65 —5.65 2.45 —0.25 —0.42 Rock phosphate produced the greatest profit, $5.82 per acre, and the manure alone produced the second largest gain, $5.45 per acre, for the six-year period. Superphosphate made an average yearly gain of $3.90 per acre and the cottonseed meal and superphosphate $2.78 per acre. 18 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION Manure with superphosphate andmanure With rock phosphate were l the only treatments that were used at a loss. The former made a yearly loss of $1.86 per acre for the siX years, while the latter produced an average yearly loss of $0.42 per acre. These two treatments pro- duced the same average yields and the diiference in the losses was caused mainly by the difference in cost of the superphosphate and rock phos- phate. Comparison of Rotated and Continuous Cotton In the preceding paragraphs the results obtained with rotated and continuous cotton were discussed separately. The average yields and profits resulting from the different treatments on both the rotated and continuous cotton are brought together in Table 9, so that the results of the two methods may be compared more readily. The average yields of lint produced by the several treatments in both rotated and continuous cotton for 13 years and for six years are given in Table 9. ' Table 9.-—Comparison of yields and profits per acre attributable to fertilizer treatments applied to rotated and contlnuous cotton. Average Profit Average Yield of Lint Per or Loss from Acre for . Fertilizer Treatment for Fertilizer Treatment 13 Years 6 Years Six Years, 1914-1927 * 1922-1927 1922-1927 Con- Con- Con- Rotated tinuous Rotated tinuous Rotated tinuous Pounds Pounds Pounds Pounds Dollars Dollars 100 lbs. cottonseed meal - 200 lbs. superphosphate . . . . . . . . . . . 205 181 218 217 —0.63 2.78 Crop residues removed . . . . . . . . . . . . 175 154 195 176 —3. 16 0.24 No treatment—check . . . . . . . . . . . . . 188 158 206 177 . . . . . . . . . . . . . . . . 200 lbs. superphosphate . . . . . . . . . . . 190 186 . 209 207 -—1.46 3.90 4 tons manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 225 7.27 5.45 4 tons manure 200 lbs. superphosphate . . . . . . . . . . . 220 181 255 206 4.42 -1 .86 107 lbs. rock phosphate . . . . . . . . . . . . . . . . . . . . . . . . . . . 216 212 2.87 5.82 107 lbs. rock phosphate . . . . . . . . . . . . . . . . . . . . . . . . . . . 221 206 —1.21 —0.42 4 tons manure Average . . . . . . . . . . . . . . . . . . . . . 196 172 224 , 203 1 .01 1.99 *Omitting 1920 on account of failure of rotated cotton. As an average of all the treatments, the rotated cotton produced 196 pounds of lint per acre a year, or 24 pounds per acre more than the con- tinuous cotton, for the 13 years. For the six years, 1922 to 1927, in-I elusive, the rotated cotton produced an average yield of 224 pounds per acre, or 21 pounds more than the continuous cotton. There was only one treatment, the manure with superphosphate, that produced sig- nificantly larger yields when applied to the rotated cotton than it did EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 19 on continuous cotton, according to Student’s method as shown in Table 10. In this case the odds or chances are 81 to 1 that the yield. of the rotated cotton, 220 pounds per acre, was greater than the yield of 181 pounds for the continuous cotton. During the six years, 1922 to 1927, inclusive, the treatment of manure alone produced an average yield of 268 pounds of lint per acre when applied to rotated cotton and 225 pounds on continuous cotton. This is a difference of 43 pounds per acre a year, which is not significant according to Student’s method on account of the fact that the rotated cotton did not produce consistently larger yields than the continuous cotton and to the short period of years; yet. in farm practice this difference in yield Would be considered significant. Tablelwr-Comparison by Studenfs method of yields of cotton grown continuously on the same land and in rotation receiving fertilizer treatments. No. of . Years Greater Smaller Odds Treatments Treatment Yield Yield Were Compared Cottonseed meal and superphosphate. . . . Rotated Continuous 6.2 : 1 13 Crop residues removed . . . . . . . . . . . . . . . . . Rotated Continuous 7 .42 : 1 13 No treatment . . . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 19.06 : 1 13 Superphosphate . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 1.0 z 1 13 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 8.38 z 1 6 Manure and superphosphate . . . . . . . . . . . . Rotated ‘ Continuous 81.4 : 1 13 Rock phosphate . . . . . . . . . . ._ . . . . . . . . . . . . Rotated Continuous 1.0 : 1 6 Rock phosphate and manure . . . . . . . . . . . . Rotated Continuous 1.91 : 1 6 The average profits and losses produced by the different treatments during the six years, 1922 to 1927, inclusive, are shown in Table 9. As mentioned previously, the gains and losses were found by subtracting the cost of the fertilizer from the value of the increase produced by the treatment. The manure was the most profitable treatment used, since it made a profit of $7.27 per acre on rotated cotton and $5.45 per acre on continuous cotton. The treatment of rock phosphate alone, however, made the largest profit, $5.82 per acre, on the continuous cotton. Corn Rotated corn and continuous corn were included in the experiment, as was pointed out in discussing the plant of the experiment. The same ‘variety of corn was not grown in the experiment every year. Fentress Strawberry was planted in 1914, 1923, and 1924c. Mosby’s Prolific was grown in 1916 and 1917. Surcropper was planted in the experiment four years, 1919, 1920, 1921, and 1922, while Chisholm was included in 1926 and 1927. Usually the stand of corn was one plant every 3 feet in the row, or 4840 plants per acre. The corn in the experi- ment was a complete failure in 1917 and 1925 on account of extreme drouth. These two years are considered, however, in computing the average yields during the period of the experiment. V20 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION Yield of Corn in Rotation The yields obtained with the corn in the rotation are shown in Table 11. It will be observed that yields were obtained from only four of the eight treatments for the 12 years. Reasonably good yields were made in 1916, 1921, 1922, and 1927. Excellent yields resulted in 1919 and 1920, considering the fact that the soil is naturally not very productive. Yields below the average for the 14 years were made in 1918, 1923, 1924, and 1926. As mentioned above, the corn was a failure in 1917 and 1925, on account of drouth. The treatment of 100 pounds of cottonseed meal and 200 pounds of superphosphate made the highest average yield, 25.9 bushels, during the 14 years of the experiment. This yield is significantly greater than the yield of the untreated check plats, the yield of the plats treated with superphosphate alone, and greater than the yield of the plats on which the residues (cotton stalks, corn stalks, etc.) were removed. (See Table 12.) During this period the untreated check plats produced an average yield of 21.8 bushels per acre and plats with the crop residues removed made 21.2 bushels per acre; while for the last six years of the experiment the former produced an average yield of 21.5 bushels and the latter 20.2 bushels per acre. This small difference in yield is not significant from a statistical standpoint; yet it shows that the removal of crop residues is reducing slightly the productiveness of the soil. v During the nine years, 1918 to 1927, excluding 1925, the treatments of cottonseed meal with superphosphate and manure alone made the highest average yield, 30.8 and 30.7 bushels per acre, respectively. The manure reinforced with 200 pounds of superphosphate gave the next highest yield, 28.2 bushels per acre. Superphosphate made an average yield of 26.8 bushels, as compared with 24.3 bushels per acre for the rock phosphate. All of the treatments were applied to the corn during the six years, 1922 to 1927, inclusive, but the corn was a failure in 1925 on account of drouth and this year is not included in the average. The treatment of manure alone produced the highest average yield, 27.2 bushels per acre, while the application of cottonseed meal and superphosphate ranked second with a yield of 26.0 bushels. This difference in yield, 1.2 bushels, is not significant. The application of 200 pounds of super- phosphate gave a yield of 22.7 bushels per acre for the five years. The addition of 100 pounds of cottonseed meal per acre to the superphosphate increased the yield from 22.7 to 26.0 bushels per acre, which is a sig- nificant increase. The yields of the different treatments on rotated corn show that manure alone made the highest yield, but it was unprofitable as will be shown later. The large yield of the manure appears to be due to the nitrogen in the manure since the addition of superphosphate to manure did not increase the yield. That this larger yield is due to the nitrogen is indicated further by the fact that the addition of cotton- seed meal to superphosphate produced significant increase in yield over lw-unfllhllk.’ ‘ "~'...‘-XM -§ EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 21 ANQ m¢5:Eo** ENE 2a 22 M55580," oNN mimN . . . . . . . . . . iwgmN wdN w.oN 9mm NAM wSN 0.5m 9mm 0.8 . . . . . . . . . . . . . . . . . . . . . . . . 1135555 53v 3.35.555 xuoh d5 hem “NAN mJNN . . . . . . . . . . ..m.mm o.oN #2 Q: w.mN mam 5mm E8 m4; ma.“ . . . . . . . . . . .. ..<..E=%o=@ #255521 HAN N.wN . . . . . . . . . . 1W8 N.wN oAN >55 o.wN 9X“ 3% Yam wdl 5mm . . . . . . . . . . .. ..@..@€wo£:@@=w.2=¢¢~ 325E mag w NBN “tom . . . . . . . . . . 15mm mNN mioN v.2 5mm mmm miwm mfim ohm wdm . . . . . E . . . . . . . . . . . . . . ..o.5:mEw5o~v nNN w? N.wN mNN new ma; 9: 5x2 wan Yo» NNw wan i: mam mam 92 ..B.£%.5@$@=m.w£o¢~ mAN 53 mam wAN mam W2 m5: wd “.8 5mm 523 52$ mp2 5.0m NAN mm: . . . . . . . . . ..fi6c5mo.s~ oZ N.oN wéN 52$ NAN w? 50m 5.3 E wan méN miom E3 98 mam wew. m.mN ...u@>oEo5 83.5mm: 530 odN wan Ndm mam mam 9mm Q2 ohm ma». 90¢ 511m >3 mNN ~25 9mm Eww ..Q..@.5QEOEQEQQE..AQ_ 8N 13E uoowcofioo a5 oom 5m .5m 5m 5m 5m .5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m $82 aim»; vim»: R2 |NN2 $22 n32 LE2 R2 $2 “N2 mNmm Nfl: 5.; 0N2 22 22 £2 n23 32 owm$>< . EQEHQQEH Eonmmiom ®.~O< 59m mmvnmsm 5m 623505 Ow 5055mm QWQZOQ ad. HQQEMQQQKQ hofimfiwm GM 5.5a UQHNQOM wO O~QGP 22 the superphosphate alone. BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION From these results it is concluded that the soil needs nitrogen first, responding readily to cottonseed meal, and manure, and that phosphoric acid did not increase the yield of corn appreciably. Table 12.—-Comparison by Student’s method of yields of rotated corn treated with different fertilizers. No. of _ Years Greater Yield Smaller Yield Odds Treatments Were Compared Cottonseed meal and superphosphate. Crop residues removed . . . . . . . . 1865.8 : 1 12 Cottonseed meal and superphosphate. No treatment . . . . . . . . . . . . . . . . 67.8 : 1 12 Cottonseed meal and superphosphate. Superphosphate . . . . . . . . . . . . . . 40.2 : 1 12 Cottonseed meal and superphosphate. Manure . . . . . . . . . . . . . . . . . . . . . 1.0 : 1 10 Cottonseed meal and superphosphate. Manure and superphosphate. . . 3.7 : 1 10 Cottonseed meal and superphosphate. Rock phosphate . . . . . . . . . . . . . . 35.7 : 1 1O Cottonseed meal and superphosphate. Rock phosphate and manure. . . 77 .3 : 1 9 No treatment . . . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 2.1 : 1 12 Superphosphate . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 4.9 : 1 12 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 25.4 : 1 10 Manure and superphosphate . . . . . . . . Crop residues removed . . . . . . . . 28.3 : 1 l0 Rock phosphate . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 1.8 : 1 10 Rock phosphate and manure . . . . . . . . Crop residues removed . . . . . . . . 2.4 : 1 9 Superphosphate . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 15.8 : 1 12 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 38.1 : 1 10 Manure and superphosphate . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 8.9 : 1 10 No treatment . . . . . . . . . . . . . . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 2.8 : 1 10 No treatment . . . . . . . . . . . . . . . . . . . . . . Rock phosphate and manure. . . 1.9 : 1 9 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Superphosphate . . . . . . . . . . . . . . 29.8 : 1 10 Manure and superphosphate . . . . . . . . . Superphosphate . . . . . . . . . . . . . . 3.9 : 1 10 Superphosphate . . . . . . . . . . . . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 5.4 : 1 10 Superphosphate . . . . . . . . . . . . . . . . . . . . Rock phosphate and manure. . . 3.3 : 1 9 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Manure and superphosphate. . . 4.7 : 1 10 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 21.6 : 1 10 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Rock phosphate and manure. . . 21.0 : 1 9 Manure and superphosphate . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 34.2 : 1 10 Manure and superphosphate . . . . . . . . . Rock phosphate and manure. . . 15.9 : 1 9 Rock phosphate and manure . . . . . . . . Rock phosphate. . . . . . . . . . . . . . 2.2 : 1 9 The money value per acre of the increase in yield of rotated corn produced by the several treatments after subtracting the cost of the fer- tilizer is shown in Table 13. The application of 107 pounds of rock phosphate was the most profitable treatment used, but it produced an average profit of only 48 cents per acre. This treatment Was used at a loss two of the five years, but made a small profit the other three years, which resulted in an average gain of 48 cents per acre for the five years. The manure alone produced large enough increases in yield to pay. for its cost two of the five years, but the losses during the other three years caused an average loss of 19 cents an acre a year. The other treatments were used at losses ranging from 75 cents to $3.84 per acre for the five vears. EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON—ROTATED CRUPS 23 Table 13.——Profit or loss per acre attributable to fertilizer treatments on rotated corn. Fertilizer Treatments 1922 1923 1924 1926 1927 Average- Dollars Dollars Dollars Dollars Dollars Dollars 100 lbs. cottonseed meal 200 lbs. superphosphate . . . . . . . . . . . 1 .35 0.16 —4.40 2.05 —2.93 -0.75 Crop residues removed . . . . . . . . . . . . -1 .08 -—4.40 -2 . 75 2.58 —1 . 63 -1 .46 200 lbs. superphosphate . . . . . . . . . . . 0.92 -0.74 —1.64 -2 .25 -1 .99 -—1 . 14 4tons manure . . . . . . . . . . . . . . . . . .. 2.47 2.90 -1.15 —1.10 —4.09 -0.19 4 tons manure 200 lbs. superphosphate . . . . . . . . . . . —7.32 -4.44 —2.79 0.19 ~4.84 —3.84 107 lbs. rock phosphate . . . . . . . . . . . -0.65 0.85 1.00 1.87 -0.65 0.48 107 lbs. rock phosphate 4 tons manure . . . . . . . . . . . . . . . . . . . —5 .23 -1.55 -1 .58 —2.77 -5.65 —3.36 Yield of Continuous Corn The yields secured with corn planted every year on the same land are reported in Table 14. Results were obtained from five of the eight treatments every year of the experiment. The corn was a failure, how- ever, in 1917 and 1925, and consequently no yields are reported for these years. While the yield of continuous corn is considerably lower than the yield of the corn grown in rotation, the effects of the fertilizer treatments are somewhat similar. The yields produced by the treatments of cotton- seed meal with superphosphate and superphosphate with manure were the same, 16.5 bushels per acre, for the 14 years, 1914 to 1927, inclusive. During this period the plat with the crop residues removed produced an average yield of 15.5 bushels per acre, or 1.0 bushel more than the plats which received no treatment, but the difference is not statistically significant according to Student’s methods, as shown in Table 15. Since the treatments of manure, rock phosphate, and manure and rock phosphate were included only during the last six years of the work, average yields were computed for all of the treatments for this period, omitting 1925 because the corn was a failure on account of drouth. The treatments of manure alone, manure with superphosphate, and manure with rock phosphate made almost identical average yields, 18.4, 18.8, and 18.2 bushels, respectively, for the five-year period. Super- phosphate with cottonseed meal produced an average yield of 15.1 bushels per acre. Superphosphate produced a slightly smaller average yield than rock phosphate, but the difference in yield was not significant. The removal of crop residues apparently has not decreased the yield of continuous corn. For the 14 years of the experiment the average yield of the plat with the residues removed was 15.5 bushels per acre as compared with 14.5 bushels for the untreated check plats, the differ- ence being due largely to the higher yield of the former in 1916, 1919, and 1920. The average yields of the plats with the residues removed and the non-treated check plats were identical for the five years, 1922, 1923, 1924, 1926, and 1927. N 0 I T A T S T N E M I R E P X E L A R w L U c I R G A S A X E T 0 9 3 0 N N I T w L U m. 24 6N3 35:80,. .22 E8 22 285x50". 3mm .. . . Ibmhmm v.2 odm 9w wflm . ... ..............ébimimnowd. ouwnawonn x002 .2: new fl-fim -||--- .-..--u- °.w - » - . . - . . . ¢ - - - - - .100. .-v-. nu --¢--. m2 ~52 93 2mm 2.4m 2w 2m 2.5 NAN #2 2mm v.2 ~62 Q42 23 ......~§=Qm¢=.:@@=m¢£8~ @2255 223w wiwm wAN Nam Q62 ozmm . . . . . ...........o.=EmEm5o~v 0.3 5x2 Q2 m2 N63 Nb wa 2mm 5R 22m “.3 2.2 mam m2 0.3 . . . . . ....@§=@m.5@$@=m.2238 0.2 22 m4; m4; 22 2m 5m 2mm mam 2mm 2S NJL mam m2 q: ...........xoonovlwaofimwvfi oZ Q2 Q2 m2 2.2 N2 “a m5 E8 Q2 2mm n.2, 92 21H 93 Q2 . . . . . . ...2.@>..E8£=Ew2 .65 2.2 N43 m2 Q: m2 2a wd Emu 2mm 93 23 2.2 9mm Q2 22 . . . . . . ...“:§Ew¢.2&..a=w252m 13E wvwwcofioo .2: com 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m +R2|~N2 $22122 R2122 . waswm 2A8» 2 ma; 3 R2 22 $2 82 22 E2 22 22 22 .22 22 E2 Ewésmmzh 232552 www$>< Jqofiiwmxo Eoummfihom E Eco mH-oscflcoo mo 0.8m .55 EoCwIE-m 03mm. Table 15.—Comparison by Student’s_ method of yields of continuous corn different fertilizers. treated with No. 0f Years Greater Yield Smaller Yield Odds Treatments Were Compared Cottonseed meal and superphosphate. Crop residues removed . . . . . . . . 8.5 : 1 12 Cottonseed meal and superphosphate. No treatment . . . . . . . . . . . . . . . . 4999.0 : 1 12 Cottonseed meal and superphosphate. Superphosphate . . . . . . . . . . . . . . 4.9 : 1 12 Manure and superphosphate . . . . . . . . . Cottonseed meal and super- phosphate . . . . . . . . . . . . . . . . . 17.4 : 1 5 Manure and superphosphate . . . . . . . .. Cottonseed meal and super~ phosphate . . . . . . . . . . . . . . . . . 1.0 : 1 12 Cottonseed meal and superphosphate. Rock phosphate . . . . . . . . . . . . . . 2.0 : 1 5 Cottonseed meal and superphosphate. Rock phosphate and manure. . . 17 .8 : 1 5 Crop residues removed. . . . . . . . . . . . .. No treatment . . . . . . . . . . . . . . . . 16.6 : 1 12 Superphosphate . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 1.0 : 1 12 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 51.0 : 1 5 Manure and superphosphate. . . . . . . . . Crop residues removed . . . . . . . . 3.2 : 1 12 Rock phosphate . . . . . . . . . . . . . . . . . . . Crop residues removed . . . . . . . . 3.4 : 1 5 Rock phosphate and manure . . . . . . . . Crop residues removed . . . . . . . . 2399.0 : 1 5 Superphosphate . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 25.3 : 1 12 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 91.2 1 1 5 Manure and superphosphate. . . . . . . . . No treatment . . . . . . . . . . . . . . . . 19.2 : 1 12 Rock phosphate . . . . . . . . . . . . . . . . . . . No treatment . . . . . . . . . . . . . . . . 3.9 : 1 5 Rock phosphate and manure . . . . . . . . No treatment . . . . . . . . . . . . . . . . 184.6 : 1 5 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Superphosphate . . . . . . . . . . . . . . 242.2 : 1 5 Manure and superphosphate. . . . . . . . . Superphosphate . . . . . . . . . . . . . . 2.4 : 1 12 Rock phosphate . . . . . . . . . . . . . . . . . . . Superphosphate . . . . . . . . . . . . . . 1.4 : 1 5 Rock phosphate and manure. . . . . . . . Superphosphate . . . . . . . . . . . . . . 48.0 : 1 5 Manure and superphosphate . . . . . . . . Manure . . . . . . . . . . . . . . . . . . . . . 1.5 : 1 5 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 11.1 : 1 5 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . Rock phosphate and manure.. . 1.0 : 1 5 Manure and superphosphate. . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 12.7 : 1 5 Manure and superphosphate . . . . . . . . Rock phosphate and manure. . . 1.9 : 1 5 Manure and rock phosphate . . . . . . . . . Rock phosphate . . . . . . . . . . . . . . 9.1 : 1 5 As was the case with rotated corn, manure produced the largest yields but not the most profitable returns per acre, as shown in Table 16. The data in Table 16 show the gains and losses produced by the several fertilizer treatments applied to corn grown on the same land every year. Rock phosphate was the most profitable treatment used, but it made an average gain of only $1.28 a year above the cost of the material. This gain was largely the result of a gain of $6.45 in 1923, since the treatment was used at a loss during three of the five years. The removal of crop residues, on the average, did not cause a loss during this period. The treatments of manure with superphosphate and cottonseed meal with superphosphate were the most unprofitable treat- ments, producing losses of $2.82 and $2.63 a year, respectively, for the five years 1922, 1923, 1924, 1926, and 1927. Comparison of Rotated and Continuous Corn The average yields of the several fertilizer treatments and the net value of the increase in yield produced by the treatments applied to rotated and continuous corn are given in Table 1'7. 26 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION Table 16.—Money value per acre of the increase in yield of_ continuous corn produced by fertilizers after subtracting cost of fertilizer. Fertilizer Treatment 1922 1923 1924 1926 1927 Average Dollars Dollars Dollars Dollars Dollars Dollars 100 lbs cottonseed meal 200 lbs. superphosphate . . . . . . . . . . . -4.13 -0.94 —4. 18 —2.21 -1.69 —2.63 Crop residues removed . . . . . . . . . . . . -0.66 -0.50 0.88 -0.42 0.85 0.03 200 lbs. superphosphate . . . . . . . . . . . 1.08 —1.24 —2.30 -2.25 -1.21 -1 .18 4 tons manure . . . . . . . . . . . . . . . . . . . 3.38 0.20 -4.21 -1.46 -—1.68 —0.74 4 tons manure 200 lbs. superphosphate . . . . . . . . . . . -3.09 —3.14 -4.00 —1.97 -1.92 —2.82 107 lbs. rock phosphate . . . . . . . . . . . -0.40 6.45 1.66 —0.65 —0.65 1.28 iotllllgsllnl:rl:lll{rg.ll?fi?lllllé . . . . . . . . . . . -1.ss -s.s5 1.06 -3.s1 0.27 -1 .39 Table 17.—Comparison of yields and net value of_ increase produced by fertilizer treatments of rotated and continuous corn. Average Yield of Corn Per Acre Net Value Per Acre of Increase Produced by Fertilizer Treatment 12 Years 5 Years Fertilizer 1 914-1927 * 1 922-1927 ** Treatment Con- Con- Con- Rotated tinuous Rotated tinuous Rotated tinuous Bushels Bushels Bushels Bushels Bushels Bushels 100 lbs. cottonseed meal 200 lbs. superphosphate . . . . . . . . . . . 30.2 19.2 26.0 15.1 ~0.75 —2.63 Crop residues removed . . . . . . . . . . . . 24.7 18.0 20.2 13.0 -1.46 0.03 No treatment——check . . . . . . . . . . . . . 25.5 16.9 21.5 13.0 . . . . . . . . . . . . . . . . 200 lbs. superphosphate . . . . . . . . . . . 26.2 18.4 22.7 14.0 —1 . 14 -1 .18 4 tons manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 27.2 18.4 ~0.19 -0.74 4 tons manure ' 200 lbs. superphosphate . . . . . . . . . . . . . . . . . . . . . . . . . . . 24. 1 18.8 -3.84 -2.82 107 lbs. rock phosphate . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.4 14.4 0.48 1.28 107 lbs. rock phosphate 4 tons manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a 22.0 18.2 —3.36 —1 .39 Average . . . . . . . . . . . . . . . . . . . .. 26.7 18.1 23.1 15.6 —1.47 —1.06 *Omitting 1917 and 1925. **Omitting 1925. The rotated corn produced decidedly larger yields than the continuous corn. The difference in yield between the rotated and continuous corn is significant in every case, except that of rock phosphate as indicated by the odds calculated by Student’s method in Table 18. During the 12 years 1914 to 1927, excluding 1917 and 1925, the rotated corn, as an average of all the treatments, made a yield of 26.7 bushels, While the- continuous corn produced 18.1 bushels per acre. This is a gain of 8.6 bushels, or 47.5 per cent, in favor of the rotated corn. The treatment. of 4 tons of manure made the largest average yield in rotated corn and the second largest yield in the continuous corn. EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 27 Table 18.——Comparison by Student's method o_f yields of_ corn grown continuously on the same land and in rotation receiving fertilizer treatments. N0. of Years Greater Smaller Odds Treatments Treatment Yield Yield Were Compared Cottonseed meal and superphosphate. . . . Rotated Continuous 9999.0 : 1 12 Crop residues removed . . . . . . . . . . . . . . . . . Rotated Continuous 3332.0 : 1 12 No treatment . . . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 4999.0 : 1 12 Superphosphate . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 1799.0 : 1 12 Manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 61.1 : 1 5 Manure and superphosphate . . . . . . . . . . . . Rotated Continuous 216.0 : 1 10 Rock phosphate . . . . . . . . . . . . . . . . . . . . . . . Rotated Continuous 13.3 : 1 5 Rock phosphate and manure . . . . . . . . . . . . Rotated Continuous 24.1 : 1 5 The last two columns of Table 17 show the value of the increase in yield produced by the treatments after deducting the cost of the treat- ment. The cost of the fertilizer materials and the prices used in deter- mining the value of the increase in yield produced by the treatments were given in the discussion of cotton. It will be noted that rock phosphate gave the largest net returns per acre on both rotated and continuous corn. This treatment produced an average gain of 48 cents per acre on rotated corn and $1.28 per acre on continuous corn for the five-year period. The removal of the cotton stalks, corn stalks, etc., from the land did not cause a loss on continuous corn, but resulted in a loss of $1.46 per acre a year on rotated corn. Yield of Oats in Rotation The oats used in the fertilizer experiment have been planted in the fall, usually in October or early November. The rate of seeding has varied from 5 to 12 peeks per acre, but in most years the rate of 8 peeks per acre was used. A variety of red rust-proof oats has been used in the experiment, but the same variety has not been grown every year. Texas Red Rust-proof, T. S. No. 1118 was planted in 1916, 1917, and 1923, while another red oat, T. S. No. 1415, was grown in 1926 and 1927. Frazier, T. S. No. 765-13, was grown in 1919, 1920, 1921, and 1922. The oats were so badly damaged by rust, lodging, and unfavorable weather conditions that yields were not obtained in 1914. In 1915, the oats winter-killed badly and were replanted in March and as a result no yields of grain were obtained. The oats failed on account of rust in 1921 and in 1924 and 1925 on account of unfavorable Weather con- ditions at time of harvest. In Table 19 are presented the yields of oats secured in the experiment. Low yields were obtained in most years, but fair yields resulted in 1918, 1919, and 1923, considering that the soil is naturally not very productive and the fact that the climatic conditions are not well adapted to small grains. The treatment of 100 pounds of cottonseed meal and 200 pounds N 0 I T A T S T N E M I R E P X E L A R U T L U C I R G A S A X E T 0 9 3 0 N N I T E L L U B 28 £2 55w 5&2 .82 MESMEOUI. .350 o5 3 @255“ 525 2E: >05 mmmm 35w 55a £505,055 mbww» m 52530.5 o5 E 503cc o5 c» 5on5?“ v.6? 355.5535 awash..." m5 5mm . . . . . . . . . . . . . . . . . . IOmCN 9mm ma; m.» 9o v.3 mimm . . . . . . . . . . . . . . . . . . . . . . . ..o555mEm:o¢¢ "53953555 x005 an: mom >55 I: E2 5.3 Ndm 52 i: 5.2 m: 54m mam 5M: 5.»; .....8.2%.E@ x852: .2: . . . . . . . . . . . . . . . . . . . . Aw.m. mw.@ . . . . . . . . . . .QHN.QQWO.SQHUQQW lmQfi “b.5555 n53 w e4; 9: . . . . . . . . IImIoH wém Won mfiw w.m wdm mdm 54m . . . . . . . . . . . . . . ....*o55:mEw:3.w i: $5 Q: 9: 5.5m .012 New dim o6 mQA 5mm 9cm 5.5 ....;.5E%.E.:QQE.2553 NA; m4: mm: 5:: Q: 9: NAN o.» 5m v8 can mAN m4; . . . . . . . . . .....~5o=5mv.~... oZ 0.2 mam 5N5 :5 HQ; 5.8 wSN ma. ms mflm 5.8 mam 9: . . . . 153,055; 355mm»! QED aem 5.5m m4; can w? mew mam 0.0m o.» 1N5 w? 5.2 i: ....dpusmmonfiiwaazmnmoom E58 wowmcofiou an: com 5m 5m 5m .5m .5m 5m 5m 5m 5m 5m 5m 5m 5m fi 5.5m 3 $8535 “N523 $5-22 mm g5 wbwo? N. Ewe? 3 n53? a Emu? q R2 $2 .32. ma“: 32 ~52 f2 :2 22 EQEEQFH Honsflhoh umm5w>< flonwsm E mEuCr v.64 63535 §Nmm 3 3am 5255a omozoU 5w acoEiwaxo 50515.50“ E 35o mo vmvtrlumm oEwH EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON—ROTATED CROPS 29 of superphosphate per acre made the highest yield in each of the follow- ing averages: the nine-year average, the 14-year average, the seven- year average, and the four-year average. The higher yield of this treat- ment apparently is due to the effect of the cottonseed meal, since the application of 200 pounds of superphosphate with or Without manure did not produce average yields significantly larger than yields of the non-treated plats or the plats with the residues removed. It is interest- ing to observe that the plat on which the crop residues were removed made the second largest yield in each of the above averages. There appears to be no consistent relation between yield and the other treat- ments. The results secured with the different treatments are somewhat variable and conflicting and for this reason it is rather hard to draw definite conclusions from them. It would appear, however, that the soil needs nitrogen before it does phosphoric acid for the production of oats. Yield of Cowpeas in Rotation Cowpeas of the Groit variety, T. S. No. 703, were used in this Work from 1915 to 1923, inclusive, while Brabham was planted in 1926 and 1927. Only yields of seed were obtained, which are given in Table 19. Satisfactory yields resulted in only one of the 14 years of the experi- ment, and that was in 1914. The cowpeas did well in 1919, but heaw rains and extended periods of damp, cloudy weather during the harvest- ing season prevented the harvesting of seed and caused the peas to rot in the field. Consequently, yields were not obtained that year. The cowpeas were a failure in 1924 and 1925 on account of drouth. The yields in the other years were low. It will be noted that the plats which received no treatment made the highest average yield for the 11-year, the 14-year, and the nine-year periods. In the four-year average the untreated plats and the treat- ment of manure with superphosphate tied for first place with respect to yield. From 1922 to 1927, inclusive, all of the treatments were applied direct to the cowpeas. As stated above, the cowpeas failed in 1924 and 1925 on account of drouth. The average yields for the other four years show there was no consistent relation between the treatments and yield. From these results it is not possible to draw definite conclusions about the work except to say perhaps that the treatments used had no effect upon yield. Discussion of Results The yields of the crops in these experiments with fertilizers conducted on Lufkin fine sandy loam soil show that the soil did not respond readily to applications of fertilizers. The results indicate, however, that the soil is more deficient in nitrogen and organic matter than it is in phosphoric acid, as shown by the fact that the application of manure alone made about as large yields as manure with superphosphate. The yield resulting from superphosphate was not significantly greater than 30 N m T A T S T N E M I R E P X E L A R . w L U w R G A S A X E T 0 9 3 0 N N I T E L L U B .3055,“ 4&2 .22 mizwiofi.“ . 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L . . . . 4 . ..@@>¢E2;2.Ew2 5050 0m 5m N.m 0Q m0 0m w; 0.N we Nm m0 N.m m.N 0m 0m . . . . . . . . . . ..@a2@w.EE@5=m.m£ooN 13E 03w 5038 an: 00H. 5m .5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m 5m Ram i052 40E “£50m mN-NNmm -022 5-32 $23 whww? v P537 0 Emu? 3 W537 I 5N2 0N2 mm: NNmm 8.2 0N0“ £2 50m 02$ 22 33 , mcocbmohm. Louzfihom wmmho>< 222m E us? 2i 625105 8N2 3 3mm 5035mm “E260 i». Euimhoaxw 532x20.“ E £2526 mo wmwtwuldN QEFH EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 31 the yield resulting from the plats which received no treatment. When, however, cottonseed meal was added t0 the superphosphate a significant increase in yield occurred, Which is further evidence that the soil is more deficient in nitrogen than it is in phosphoric acid. In this experiment, rock phosphate produced as large yields as super- phosphate. Since the rock phosphate produced as large yields as super- phosphate and Was much cheaper than the latter, it is clear that rock phosphate was the more profitable material. The removal of crop residues, such as cotton stalks and corn stalks, reduced slightly but not significantly the productiveness of the soil. This is an interesting fact since it would be expected that the removal of crop residues for a period of 14 years would cause an appreciable and significant decline in the fertility of the soil. These results indi- cate that this particular soil does not respond readily to the application of fertilizers or to such bad farm practice as removing the crop residues, such as cotton stalks and corn stalks, year after year. While the results reported here show the Lufkin fine sandy loam responded more readily to nitrogenous fertilizers than it did to phos- phatic fertilizers, the work was not comprehensive enough to show definitely the best fertilizer treatments for the particular conditions. The application of manure, however, was the most profitable treatment used. EFFECT OF ROTATION ON YIELD OF CROPS The effects of fertilizers on the yield of crops grown in rotation and on crops grown continuously on the same land have been discussed previously. It is desirable at this point to compare directly the yields of the crops grown in rotation with the yield of the same crops grown on the same land every year to show the effect of rotation on yield. Since cotton and corn were the only crops in the experiment that were grown on the same land every year, the study of the effect of rotation on yield will be restricted to these crops. In comparing the yields of rotated and non-rotated crops, it should be remembered that the fertilizer treatment, variety of crop, seed-bed preparation, planting, cultivation, and harvesting were the same in both systems of cropping. The only difference was that the crop, cotton for example, was grown continuously on the same land in one case, and in rotation with corn, cowpeas, and oats in the other. Cotton The average yields of rotated cotton and of continuous cotton for the 13 years, 1914 to 1927, are shown in Table 21. As an average of all the treatments, the rotated cotton made an average yield of 196 pounds per acre, or 24 pounds per acre more than the yield of con- tinuous cotton. This is a clear gain of 14 per cent in~favor of the rotated cotton. I 32 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION 1mm 4- ‘*‘ A B C D Fig. 1. The yield of cotton grown continuousliy on the same land, 158 pounds of lint per acre: is shown in A; B shoyvs the increase in yiel produced by_ fertilizer; C shows the increase in (yield produced by rotation alone; and D gives the increase 1n yield resulting from fertilizer an rotation used together. EXPERIMENTS WITH FERTILIZERS Ol\l ROTATED AND NON-ROTATED CROPS 33 Table 21.—Average yield in pounds of lint per acre of rotated and continuous cotton for years. Average Yield of Lint Per Acre During 13 Years, 1914-1927* Treatment _ Increase Rotated Continuous Due t0 Cotton Cotton Rotation - Pounds Pounds Pounds 100 lbs. cottonseed meal 200 lbs. superphosphate . . . . . . . . . . . . . . . . . . . . . . . . . 205 181 24 Crop residues removed . . . . . . . . . . . . . . . . . . . . . . . . . . 175 154 21 No treatment—check . . . . . . . _ . . . . . . . . . . . . . . . . . . . 188 158 30 200 lbs. superphosphate . . . . . . . . . . . . . . . . . . . . . . . . . 190 186 4 4 tons manure ‘ 200 lbs. superphosphate . . . . . . . . . . . . . . . . . . . . . . . . . 220 181 39 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 172 24 *Omitting 1920 on account of failure of rotated cotton. Figure 1 shows the effect of rotation and fertilizer on the yield of cotton. The yield of continuous cotton, 158 pounds of lint per acre, is shown in A of Figure 1, and may be considered as the effect of tillage on yield. The unfertilized cotton in rotation made an average yield of 188 pounds of lint per acre, or 30 pounds per acre more than the un- fertilized cotton grown continuously on the same land, as shown in C. Continuous cotton, where fertilized with manure and superphosphate, produced 181'pounds of lint per acre, or 23 pounds per acre more than the yield of continuous cotton which received no treatment, as indicated in B. This represents the effect of fertilizer alone on the yield of cotton. Rotated cotton which was fertilized made an average yield of 62 pounds of lint per acre more than continuous cotton which received no fertilizer, as shown in D of Figure 1. This increase of 62 pounds is the combined effect of rotation and fertilizer on the yield of cotton. The increase caused by rotation and fertilizer combined is greater than the sum of the increases produced by rotation and fertilizer used separately. C 0TH The average yields of rotated and of continuous corn for 12 years are given in Table 22. During this period the rotated corn, considering all of the treatments, made an average yield of 26.7 bushels per acre, or 8.6 bushels per acre more than the yield of continuous corn. This increase of 8.6 bushels represents an increase of 47.5 per cent over the yield of continuous corn. The rotated corn in the case of every treat- ment made considerably higher average yields than continuous corn with the same treatment. The increases in yield of corn due to rotation and to the use of fer- tilizer are shown in Figure 2. The yield of continuous corn, 16.9 bushels per acre, is shown graphically in A of Figure 2. This yield may be considered as the result of tillage alone. The unfertilized corn 4,4 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION “ A B Fig. 2. The yield of corn _grown o_n the same land every year, 16.9 bushels per acreis represented by ; B shows the increase 1n yield made by_ fertilizer; C shows the increase in o >‘v 0 o $4 >:9.$:o' ‘n A C.D yield produced by rotation; While D gives the increase in yield produced by fertilizer and r0ta— tion when used together. F y ~ “Vi; EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 85- in rotation made an average yield of 25.5 bushels per acre, or 8.6 bushels more than unfertilized continuous corn, as shown in C. When the continuous corn was fertilized (with cottonseed meal and‘super- phosphate) the yield was increased 2.3L bushels per acre, as shown in B ;. this yield represents the effect of fertilizer on the yield of corn. Corn in rotation which was fertilized produced an average yield of 30.2 bushels per acre, or 13.3 bushels more than the yield of unfertilized corn grown continuously on the same land (D, Figure 2). This represents- the combined effect of rotation and fertilizer on the yield of corn. The results above show clearly that the increase in yield produced by the rotation was nearly four times as large as the increase produced by fertilizer alone. The increase resulting from the joint use of rotation and fertilizer was greater than the sum of the increases produced by rotation and fertilizer separately. Table 22.—~Average yield in bushels per acre of rotated and continuous corn for 12 years. Average Yield in Bushels Per Acre for 12 Years, 1914-1927* Treatment — - Increase Rotated Continuous Due _to Corn Corn Rotation Bushels Bushels Bushels 100 lbs. cottonseed meal 200 lbs. superphosphate . . . . . . . . . . . . . . . . . . . . . . . . . 30.2 19.2 11.0 Crop residues removed . . . . . . . . . . . . . . . . . . . . . . . . . . 24.7 18.0 6.7 No treatment-check . . . . . . . . . . . . . . . . . . . . . . . . . . . 25.5 16.9 8.6 200 lbs. superphosphate . . . . . . . . . . . . . . . . . . . . . . . . . 26 .2 18.4 7.8 Average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 26.7 18.1 8.6 *Years 1917 and 1925 omitted on account of failure. The results obtained with cotton and corn show that ‘rotation of crops is conducive to the more eflicient use of fertilizers. Rotation in- creased the yield of these crops more than the fertilizers, but the best- results were obtained by the combined use of rotation and fertilizers. THE VALUE OF CROPS IN ROTATION The effect of fertilizers and rotation on the yield of crops and the- profits derived from the use of fertilizers have already been discussed. It now remains to show the money value of crop rotation by comparing the value of the crops grown in rotation with the value of the same» crops grown continuously on the same land. It is desirable to know the cost of producing the crops and the profits! that may be reasonably expected in order that the farmer may make an intelligent choice of his farm enterprise, including the proper use of fertilizers, rotation of crops, and the most efficient utilization of these crops. Accordingly, the total value per acre, the cost of production, and the net returns per acre of the four crops, cotton, corn, oats, and. 36 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION cowpeas, were determined. In computing the value of the crops the estimated prices of cotton, corn, and oats as received by producers on December 1 of each year, as given in the Yearbooks of the United States Department of Agriculture, were used. The value of the oat crop included both grain and straw, the latter being valued at $10.00 a ton, which was the average price per ton of straw sold. The cowpeas were figured at $3.00 a bushel, which was the average price received for the cowpeas. The total cost of producing the crops was based largely on figures obtained in detail cost studies made by the Division of Farm and Ranch Economics of this Station, in Rockwall and Collin counties in 1925 and 1926. The cost of production of the crops in- cludes all expenses incurred in actually producing and harvesting the crops and preparing them for market. . Table 23 gives the average yearly gross returns per acre, cost of pro- duction, and average net return per acre of cotton, corn, oats, and cow- _ peas for the four years 1922, 1923, 1926, and 1927. Rotated cotton made the largest profit,~$22.11 per acre, which, however, was only slightly more than the profit of the continuous cotton. Continuous corn gave the smallest profit, which was only $1.52 per acre. Table 23.—Average value per acre of cotton, cowpeas, corn, and oats {for the four years, 1922, 1923, 1926, and 1927. _ Gross Cost of Net Kind of Crop Returns Production Returns Per Acre Per Acre Per Acre Continuous cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 41 .49 $ 19.74 $ 21.75 Continuous corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.89 9.37 1 .52 Rotated cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 . 59 19.48 22. 11 Rotated corn . . . . . . . . . . . . . . . . . . .* . . . . . . . . . . . . . .. 16.77 10.17 6.60 Rotated cowpeas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.90 13.16 2.74 Rotated oats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.54 8.24 5.30 Average for rotated crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $ 9.19 The average net returns of the four crops, cotton, cowpeas, corn, and oats, grown in rotation was $9.19 per acre a year for the four years. The continuous cotton made a profit of $21.75 per acre a year. This shows clearly that this particular rotation was not as profitable as con- tinuous cotton and is not recommended to the farmers in the region. While the crops in the four-year rotation did not produce as large an average net return per acre as continuous cotton, the data in Table 23 are valuable in showing the value per acre of the several crops. These data show that cotton had a higher value per acre than the other crops. The table also shows that cowpeas, when grown for seed as they were in this experiment, were not profitable and consequently should not be used for this purpose in a rotation in this region. Corn and oats pro- duced much smaller net returns per acre than cotton. Although corn has a rather low value per acre on the basis calculated, it is one of the best grain crops for this part of the State and should be included in EXPERIMENTS WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 37 the cropping system, for the reason that it may be planted, cultivated, and partially produced at a time when the farm labor and equipment would not be used in producing cotton. Furthermore, the corn pro- duced and fed on the farm may be valued at the retail price of corn, that is, the price the farmer would pay if he were to buy the corn, which would be considerably more than the farm price of corn used in calculating the acre value of corn in Table 23. This simply means that if the corn grown on the farm is fed to the farm livestock, the acre value of the corn crop will be greater than the value of the crop com- puted on the basis of the farm price as Was done in the above table. While the four-year rotation of cotton, cowpeas, corn, and oats was not profitable, largely on account of the low value of the cowpeas, a ' two-year rotation of cotton and feed crops (corn as the grain crop and sorgo, Sudan grass, or cowpeas for hay) should be satisfactory. As a rule, a rotation should include a legume such as cowpeas or-vetch on account of their soil-enriching properties. The legume should be used as a feed or cash crop if it is grown during the regular growing season because it is worth more as a feed crop than it is for soil improvement. If the legume is cut for hay, the residues including the stubble or manure resulting from grazing the stubble or aftermath (second growth), should be plowed under to improve the land. Catch crops, such as cowpeas planted on oat stubble, cowpeas planted in corn at the last cultivation of the corn, or winter cover crops such as vetches may be plowed under for soil improvement or they may be grazed off and the residues plowed under. It should be pointed out here that it is a sound business policy for the farmer to produce all the feed he needs for his livestock. After the required feedstuffs have been provided, he may devote his attention to the growing of cotton. The cropping system then may be conveniently called a two-year rotation of cotton and feed crops, as mentioned above. This two-year rotation does not require that one-fourth, one-third, or one-half of the land be devoted to each crop grown. It merely requires that enough feed crops be grown to furnish the feed required by the livestock on the farm. The feed crops should be planted each year on land that grew cotton the previous year. The cotton would be planted on the remaining land not in other crops. i Since it is good business policy to produce the feed required on the farm and since rotation increases the yield of crops, it follows that the crops that are grown should be included in a rotation. It is clear, there- fore, that a rotation costs the farmer nothing and the larger yields resulting from the rotation represent so much gain or profit. In operating a farm as a business enterprise, the farmer should bear in mind that usually there is a certain amount of labor and equipment, such as work stock and machinery, available on the farm during the year. If the one-crop system, whether it consists of cotton, corn, or other crops, is practiced there will be times when the labor and equip- ment will be idle and consequently non-productive. If suitable rota- 3 » farming profitable. 38 BULLETIN NO. 390, TEXAS AGRICULTURAL EXPERIMENT STATION tions are used, two or more crops may be grown and, as a result, the Y In the two-year rota- » tion of cotton and feed crops mentioned above, the corn may be planted i The land may be prepared/l’ for corn and the corn planted at a time that would not interfere with In this way, the labor and equipment may be 5 used to grow feed or cash crops other than cotton‘ at times when they labor may be distributed to a better advantage. a month or six weeks earlier than cotton. the planting of cotton. could not be used to produce cotton, which would of course result in a larger income. In this connection it should be emphasized that the proper distribu- ‘ tion of labor during the year is one of the main factors in making * While it is shown above that cotton makes larger“ profits per acre than the other crops, yet the more suitable feed crops may be grown to advantage because they may be produced at a time when the labor and equipment would not be used in the production of cotton. The result is that the income from these crops may be con- sidered largely as profit, since the labor and equipment would not have been used if the one-crop system had been followed. SUMMARY These experiments with fertilizers were conducted on Lufkin fine sandy loam, which is an extensive soil in certain parts of southeastern Texas. Associated with this soil are other soils somewhat related in character to which-these results will probably also apply to a consider- able extent. Nitrogenous materials, manure and cottonseed meal, produced larger increases in yield of cotton and corn than phosphoric acid, which indi- cates that the soil is more deficient in nitrogen than it is in phosphoric acid. Application of four tons of manure per acre each year to cotton pro- duced the largest yields and the greatest profits over a period of six years, when both rotated and continuous cotton are considered. Rock phosphate, however, made a slightly larger profit per acre on continuous cotton than did manure. ' Rock phosphate and superphosphate were equally effective in increas- ing the yield of cotton and corn. Since the rock phosphate is the cheaper of the two materials, it was the more profitable. Manure in combination with rock phosphate increased the yields of cotton and corn but it was used at a loss on both of these crops over a period of years. Manure and superphosphate, however, when applied to rotated cotton made an average gain of $4.42 per acre above its cost, for the six years 1922 to 1927. The removal of the crop residues (cotton stalks and corn stalks, etc.) caused a slight but not a significant decline in the produetiveness of the soil. i The fertilizers apparently did not increase the yield of either oats or cowpeas. “'.-_z.,.1.»-._.. y .. EXPERIMENTS ~WITH FERTILIZERS ON ROTATED AND NON-ROTATED CROPS 39 Rotation increased the yield of cotton 14 per cent and the yield of corn 47.5 per cent. The rotated cotton and continuous cotton were about equally profitable, returning a profit of $22.11 and $21.75 per acre, respectively, above the cost of production, over a period of four f years. Rotated corn gave an average net return of $6.60 per acre. Corn grown continuously on the same land made a profit of only $1.52 per acre. The average net return of the four crops in the rotation was I $9.19 as compared with $21.75 per acre for continuous cotton. ACKNOWLEDGMENTS The experiment was established in 1914 by Mr. A. H. Leidigh, then Agronomist, who had charge of the Work up to 1920, after Which the author assumed charge. Mr. D. T. Killough, former superintendent, and Mr. G. T. McNess, Superintendent of the Main Station Farm, con- ducted the field Work and collected data after 1923.