LIBRARY. A & M corneas. CAMYUS. TEXAS AGRICULTURAL EXPERIMENT STATIUN A. B. CONNER, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 469 DECEMBER, 1932 DIVISION OF AGRONOMY Fertilizer Experiments with Cotton AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. 0. WALTON, President STATION STAFFT Administration : A. B. Conner, M. S., Director R. E. Karper, M. S., Vice-Director Clarice Mixson, B. A., Secretary M. P. Holleman, Chief Clerk J. K. Francklow, Asst. Chief Clerk Chester Higgs, Executive Assistant Howard Berry, B. S., Technical Asst. Chemistry: . S. Fraps, Ph. D., Chief; State Chemist E. Asbury, M. S., Chemist F. Fudge, Ph. D., Chemist C. Carlyle, M. S., Asst. Chemist . L. Ogier, B. S., Asst. Chemist . J. Sterges, M. S., Asst. Chemist Ray Treichler, M. S., Asst. Chemist W. H. Walker, Asst. Chemist Velma Graham, Asst. Chemist Jeanne F. DeMottier, Asst. Chemist R. L. Schwartz, B. S., Asst. Chemist C. M. Pounders, B. S., Asst. Chemist Horticulture: S. H. Yarnell, Sc. D., Chief Range Animal Husbandry: J. M. Jones, A. M.. Chief B. L. Warwick, Ph. D., Breeding Investiga. S. P. Davis, Wool Grader I**J. H. Jones, B. S., Agent in Animal Hush. Entomology: F. L. Thomas, Ph. D., Chief; State Entomologist H. J. Reinhard, B. S., Entomologist R. K. Fletcher, Ph. D., Entomologist W. L. Owen, Jr., M. S., Entomologist J. N. Roney, M. S.. Entomologist J. C. Gaines, Jr., M. S., Entomologist S. E. Jones. M. S., Entomologist F. F. Bibby, B. S., Entomologist "E. W. Dunnam, Ph. D., Entomologist "‘*R. W. Moreland, B. S., Asst. Entomologist C. E. Heard, B. S., Chief Inspector C. Siddall, B. S., Foulbrood Inspector >epPWQ Veterinary Science: *M. Francis, D. V. M., Chief , H. Schmidt, D. V. M., Veterinarian ‘ "F. P. Mathews, D.V.M., M.S., Veterinarian R. A. Goodman, D. V. M., Veterinarian Plant Pathology and Physiology: J. J. Taubenhaus, Ph. D., Chief W. N. Ezekiel, Ph. D., Plant Pathologist Farm and Ranch Economics: L. P. Gabbard, M. S., Chief W. E. Paulson, Ph. D., Marketing TTC. A. Bonnen, M. S., Farm Management '.t**W. R. Nisbet, B. S., Ranch Management A. C. Magee, M. S., Farm Management Rural Home Research: Jessie Whitacre, Ph. D., Chief' Mary Anna Grimes, M. S., Textiles Elizabeth D. Terrill, M. A., Nutrition Soil Survey: **W. T. Carter, B. S., Chief E. H. Templin, B. S., Soil Surveyor A. H. Bean, B. S., Soil Surveyor R. M. Marshall, B. S., Soil Surveyor Botany: V. L. Cory, M. S., Acting Chief Swine Husbandry: Fred Hale, M. S., Chief Dairy Husbandry: O. C. Copeland, M. S., Dairy Husbandman Poultry Husbandry: R. M. Sherwood, M. S., Chief J. R. Couch, B.S., Asst. Poultry Husbandman Agricultural Engineering: H. P. Smith, M. S., Chief Main Station Farm: G. T. McNess, Superintendent Apiculture (San Antonio): H. B. Parks, B. S., Chief A. H. Alex, B. S., Queen Breeder Feed Control Service: F. D. Fuller, M. S., Chief James Sullivan, Asst. Chief S. E. McGregor, B. S., Foulbrood Inspector S, D, Pearce, Secretary Agflmomyi J. H. Rogers, Feed Inspector E- B- RQYHOMS, Ph- D» Chief K. L. Kirkland, B. S., Feed Inspector R- E- Karpel‘, M. S., AgrOIIOIYIiSlI S. D. Reynolds, Jr., Feed Inspector P. C. Mangelsdorf, Sc. D., Agronomist P. A. Moore, Feed Inspector D. T. Killough, M. S., Agronomist E. J. Wilson, B. S., Feed Inspector Pllblicfltiollflr H. G. Wickes, D. V. M., Feed Inspector A. D. Jackson, Chief SUBSTATIONS No. 1, Beeville, Bee County: R. A. Hall, B. S., Simerintendent No. 2, Lindale, Smith County: P. R. Johnson, M. S., Superintendent No. 9, Balmorhea, Reeves County: J. J. Bayles, B. S., Superintendent No. 10, College Station, Brazos County: R. M. Sherwood, M. S., In Charge “B. H. Hendrickson, B. S., Sci. in Soil Erosion L. J. McCall, Farm Superintendent "R. W. Baird, B. S., Assoc. Agr. Engineer No. 3, Angleton, Brazoria County: R. H. Stansel, M. S., Superintendent H. M. Reed, M. S., Horticulturist No. 4, Beaumont, Jefferson County: R. H. Wyche, B. S., Superintendent **H. M. Beachell, B. S., Junior Agronomist No. 5, Temple, Bell County: Henry Dunlavy, M. S., Superintendent C. H. Rogers, Ph. D., Plant Pathologist H. E. Rea, B. S., Agronomist S. E. Wolff, M. S., Botanist "H. V. Geib, M. S., Sci. in Soil Erosion **H. O. Hill, B. S., Junior Civil Engineer No. 6, Denton, Denton County: P. B. Dunkle, B. S., Superintendent **I. M. Atkins, B. S., Junior Agronomist No. 7, Spur, Dickens County: R. E. Dickson, B. S., Superintendent B. C. Langley, M. S., Agronomist No. 8, Lubbock, Lubbock County: D. L. Jones, Superintendent Frank Gaines, Irrig. and Forest Nurs. Teachers in \the School of Agriculture G. W. Adriance, Ph. D., Horticulture S. W. Bilsing, Ph. D., Entomology V. P. Lee, Ph. D., Marketing and Finance D. Scoates, A. E., Agricultural Engineering A. K. Mackey, M. S., Animal Husbandry *Dean, School of Veterinary Medicine. "In cooperation with U. S. Department of Agriculture. No. 11, Nacogdoches, Nacogdoches County: H. F. Morris, M. S., Superintendent **No. 12, Chillicothe, Hardeman County: “J. R. Quinby, B. S., Superintendent **J. C. Stephens, M. A., Asst. Agronomist No. 14, Sonora, Sutton-Edwards Counties: W. H. Dameron, B. S., Superintendent I. B. Boughton, D. V. M., Veterinarian W. T. Hardy, D. V. M., Veterinarian O. L. Carpenter, Shepherd **O. G. Babcock, B. S., Asst. Entomologist No. 15, Weslaco, Hidalgo County: W. H. Friend, B. S., Superintendent S. W. Clark, B. S., Entomologist W. J. Bach, M. S., Plant Pathologist J. F. Wood, B. S., Horticulturist No. 16, Iowa Park, Wichita County: C. H. McDowell. B. S., Superintendent L. E. Brooks, B. S., Horticulturist No. 19, Winterhaven, Dimmit County: E. Mortensen, B. S., Superintendent "L. R. Hawthorn, M. S., Horticulturist Carrying Cooperative Projects on the Station: J. S. Mogford, M. S., Agronomy F. R. Brison, B. S., Horticulture W. R. Horlacher, Ph. D., Genetics J. H. Knox, M. S., Animal Husbandry A. L. Darnell, M. A., Dairy Husbandry TAs of December 1, 1932. 1' TOn leave. iIn cooperation with Texas Extension Service. The results 0f seven years experiments with fertilizers on cotton at Troup, Nacogdoches, Angleton, College Station, Beeville, Tem- ple, and Denton, Texas, are reported in this Bulletin. The Kirvin fine sandy loam at Troup and the Nacogdoches and Ruston fine sandy loams at Nacogdoches are deficient in nitrogen, phosphoric acid, and to a somewhat lesser extent in potash. The use of 200 to 400 pounds per acre of a 4-8-4 or 4-6-4 fertilizer or a fertilizer which furnishes equivalent amounts and proportions of plant food is suggested for cotton on these soils. The Lake Charles clay, an extensive soil in the Gulf Coast Prairie, is markedly deficient in phosphoric acid, as indicated by the results obtained on this soil at Angleton. The use of 100 pounds of superphosphate or 200 to 600 pounds of a 4-8-0 fer- tilizer per acre is recommended for cotton on the Lake Charles clay and similar soils of the region. The Lufkin fine sandy loam at College Station responded bet- ter to applications of phosphoric acid and of potash than to appli- cations of nitrogen. The 4-12-4 and 0-12-4 fertilizers used at the rate of 400 pounds per acre were the most profitable treatments on this soil. The dark-colored Goliad fine sandy clay loam at Beeville, the Houston black clay and Houston clay at Temple, and the San Saba clay at Denton, gave some response to fertilizers, but as a rule the use of fertilizers on these soils was not profitable. CONTENTS Page Introduction _ . . . . _ _ _ . _ . . -_ _ 5 Review of Previous Fertilizer Work in Texas“- 6 Method of Conducting the Fertilizer Work ,,,, __ 7 Grades and Amounts of Fertilizers Used ___________________________________________________ __ 8 Method of Applying Fertilizer 8 Crop Rotations ...... -- 9 Location of the Work 9 Experimental Results ' 9 Results Obtained on Kirvin Fine Sandy Loam at Troup ______________________ __ 9 Results Obtained on the “Red Lands” at Nacogdoches ________________________ __12 Results Obtained on the Lake Charles Soils at Angleton ____________________ Results Obtained on Lufkin Fine Sandy Loam at College Station._-i19 Results Obtained on the Goliad Soils at Beeville ____________________________________ __21 Results Obtained on the Houston Soils at Temple ____________________________________ __24 Results Obtained on the San Saba Soils at Denton ______________________________ __25 Profits Obtained from the Use of Fertilizers___ 26 Discussion of Results _ . . . . _ . . -- 29 Summary ' __31 BULLETIN NO. 469 i DECEMBER, 1932 FERTILIZER EXPERIMENTS WITH COTTON E. B. Reynolds, G. T. McNess, R. A. Hall, P. R. Johnson, R. H. Stansel, Henry Dunlavy, P. B. Dunkle, and H. F. Morris Climatic conditions, especially temperature, evaporation, and the amount and distribution of rainfall, have a profound influence on the development of soils and on the physical, chemical, and biological properties of the soil. Normal soils developed under humid conditions are usually more or less leached and do not contain, as a rule, as much available plant food as nor- mal soils formed under sub-humid or arid conditions. For instance, the more completely developed‘ soils in the eastern part of the United States, where humid conditions prevail, are in general leached of lime and other bases and are acid in the surface and subsoil. On the other hand, soils developed under less humid conditions, such as those prevailing in the Great Plains Region, instead of being leached of plant food, have an accu- mulation of lime, usually in the subsoil. The soils in warm, moist climates, such as the climate in the cotton-belt states, usually do not contain large amounts of organic matter, because the high temperatures and favorable moisture conditions lead to the rapid decomposition of the organic matter. Under these conditions, the processes of decay and decomposition take place so rapidly that large amounts of organic matter do not accumulate in the soil. On the other hand, in cool climates, with an equivalent amount of rain- fall, as in the Northern states and Canada, the soils contain more organic matter than those in hot climates. This is due to the fact that here the environmental conditions, including temperature and moisture, during the growing season are favorable for abundant vegetative growth, while during the long, cold winters, the processes of decay take place slowly or are retarded entirely on account of the low temperature. These conditions, therefore, are favorable for the‘ accumulation of large amounts of organic matter in the soil. The climate in Texas ranges from extremely humid in the southeastern part, where the average annual rainfall is 50 inches or more, to arid in the extreme western part, where the rainfall is approximately 10 inches. These climatic differences account in part for the occurrence of so great a variety of soils in the State. The many different kinds, or types, of soils in Texas range in texture from light sandy soils to stiff, heavy clay soils, and vary considerably in chemical composition and in content of plant food. These soils also vary widely in productiveness, on account of the differences of plant food, tex- ture, and structure. It is obvious that differenfsoils may require different kinds of fertilizers. For example, light, deep‘ sandy soils are more likely to be deficient in potash than are clay soils,» because they contain smaller amounts of potash-containing .minerals. Further, the dark-colored soils of the Lake Charles series in the Gulf Coast Prairie are deficient in phos- phoric acid, as shown by the fact that they respond readily to applications of phosphatic fertilizers. Other soils respond to applications of complete 6 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION fertilizers. In the western part of the State, moisture, and not plant food, is generally the first limiting factor in crop production, and fertilizers as a rule have had little or no influence on crop production except under irri- gation. REVIEW OF PREVIOUS FERTILIZER WORK :IN TEXAS When the Texas Agricultural Experiment Station was established in 1888, field experiments with various field and garden crops were begun to de- termine the most practical methods of production under the diverse condi- tions prevailing in the State. These experiments included trials with dif- ferent fertilizers and fertilizer materials for the purpose of ascertaining the best kinds and amounts for the main crops on the more important soils. The results of the first of these experiments, which dealt with cotton, corn, and wheat at McKinney and Wichita Falls, were published in Bulletin 34 (1895). In a discussion of the results obtained with cotton at McKinney, it was stated, “Using the past year’s results as a basis of calculation, it is highly probable that a judicious combination of phosphoric acid and nitrogen will give a satisfactory profit on their use in growing cotton on the black lands.” The fact that the soil responded somewhat to applica- tions of nitrogen and phosphoric acid agree in general with the more recent work with fertilizers on the Houston soils at Temple, although the fer- tilizers were not profitable. Experiments with fertilizers conducted at College Station 1n 1897 and 1898 indicated that the soil (Lufkin fine sandy loam) responded more readily to applications of nitrogen and of phosphoric acid than to applica- tions of potash. As an average for the two years, superphosphate increased the yield of cotton 23.9 per cent; bone black, 38.8 per cent; cottonseed meal, 39.9 per cent; and potash, 6 per cent. In 1903, Dr. H. H. Harrington, then Chemist of the Experiment Station and State Chemist, on the basis of the results obtained with fertilizers in Texas up to that time, suggested some fertilizers for various crops. For example, he recommended a 3-9-4 fertilizer for cotton, which is practi- cally equivalent to the 4-8-4 analysis in total plant food now used so ex- tensively in Texas and other States. Experiments conducted at Troup from 1902 to 1911 with fertilizers for sweet potatoes, Irish potatoes, watermelons, and strawberries indicated that the gray, sandy soil (now called the Kirvin fine sandy loam) was deficient in phosphoric acid and nitrogen and to some extent in potash. The results of the Work on Irish potatoes, published in Bulletin 101, showed that the soil needed mostly nitrogen and phosphoric acid, although potash was beneficial to some extent. In trials with sweet potatoes, superphosphate increased the yield 33 1-3 per cent; cottonseed meal, 36 per cent; and nitrate of soda, 31 per cent. A mixture of three parts of superphosphate and two parts of cottonseed meal gave the best results. A complete fertilizer gave the largest yield of watermelons. With strawberries, however, the largest yields were obtained from a mixture of cottonseed meal and superphos- FERTILIZER EXPERIMENTS WITH COTTON 7 phate; potash was not effective. More recent work has confirmed the earlier results, and, in addition, has shown that potash is needed by most crops. The results of fertilizer work conducted with cotton, corn, and tomatoes on the red lands at Nacogdoches from 1911 to 1920 also pointed to a de- ficiency of nitrogen and phosphoric acid, which also has been confirmed by later fertilizer work with cotton and corn. Results of fertilizer experiments with cotton at Beaumont in 1916 and 1917 showed that the soil was deficient in both nitrogen and phosphoric acid and that phosphoric acid is the first limiting element. The results of trials with fertilizers on rice over a period of 13 years, published in Bul- letin 398, show that the soil also responds to a complete fertilizer, al- though the most profitable results were obtained from the use of sulphate of ammonia‘ alone. Dr. G. S. Fraps, in his capacity as State Chemist in charge of the fer- tilizer control law, conducted a large number of field experiments with fertilizers on several crops in cooperation with farmers in the different parts of the State from 1908 to 1917. The results of these experiments were published in Bulletins 138 and 235. Of ‘the 151 experiments con- ducted with cotton as reported in Bulletin 235, 74 per cent gave an increase in yield with superphosphate, 68 per cent with cottonseed meal, and 58 per cent with potash. It was stated in Bulletin 138 that “Texas soils are likely to be deficient in phosphoric acid first of all, next in nitrogen, and last and least in potash.” The above discussion of the earlier fertilizer work conducted by the Experiment Station indicates in a general way that the sandy soils in the eastern part of the State are deficient in nitrogen and phosphoric acid and to some extent in potash. Further, the black Waxy soils (Houston soils) showed some response to nitrogen and phosphoric acid. These earlier results, however, did not indicate definitely the best proportions of plant food (nitrogen, phosphoric acid, and potash) and the rate of applica- tion to be used on specific soils. In View of this fact the fertilizer Work was revised and expanded in 1927 with the view of determining definitely the best kinds and amounts of fertilizer for the more important field crops on the major soil types in the different parts of the State. Cotton, corn, wheat, and oats were the crops used in these studies. It is the object of this Bulletin to report the results obtained with cotton at the several substations. Later it is planned to publish the results of the fertilizer work with corn, wheat, and oats in other bulletins. METHOD OF CONDUCTING THE FERTILIZER WORK In this work a 4-12-4 fertilizer made up from sulphate of ammonia, superphosphate, and muriate of potash, applied at the rate of 400 pounds per acre, was used as the basic treatment. Then the percentage of each element—nitrogen, phosphoric acid, and potash—was varied in turn, while the other two were kept constant. For example, the percentage of nitrogen ranged from 0 to 8 per cent by using 0-12-4, 4-12-4, 6-12-4, and 8-12-4 8 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION analyses. It will be observed that the content of phosphoric acid remained at 12 per cent and the content of potash at 4 per cent, While the nitrogen varied from 0‘ to 8 per cent. In these analyses, the first figure means the percentage» of nitrogen, the second the percentage of available phos- phoric acid, and the third the percentage of water-soluble potash. Varia- tions in the percentage of phosphoric acid and of potash were studied in a like manner. This arrangement enables one to determine the best analysis of fertilizer (the ratio of nitrogen, phosphoric acid, and potash) for the various soil types. Grades and Amounts of Fertilizers Used The following fertilizer treatments were used in these experiments: Analyses Rate, pounds per acre Nitrogen varied: 0-12-4 400 4-12-4 400 6-12-4 400 8-12-4 400 Phosphoric acid varied: N P K 4-0-4 400 4-6-4 400 4-8-4 i 400 4-12-4 400 Potash varied: N P K 4-12-0 400 4-12-2 400 4-12-4 400 2 4 200 2 4 400 2-4 600 2 4 800 2 8 800 Other treatments, including manure, were used at some of the stations and these will be mentioned in the discussion of the results at the places concerned. Method of Applying Fertilizer The various grades of fertilizer With the desired ratio of nitrogen, phos- phoric acid, and potash were made up by weighing the correct amounts of sulphate of ammonia, superphosphate, and muriate of potash, mixed, and applied to the soil soon afterward. In most cases the fertilizers were applied by distributing as uniformly as possible by hand in a furrow about two weeks before planting and ridges or beds were made on the fertilizer. The cotton was planted on these beds, the seed being placed about 11/2 ‘to 2 inches above the fertilizer. Each fertilizer treatment occurred two to four times in the experiment at each station. FERTILIZER EXPERIMENTS WITH COTTON 9 Crop Rotations The fertilizer work at each substation was conducted in a rotation of crops. The rotation used at a particular substation is given in the discus- sion of the experiment at that station. In connection with the judicious use of fertilizers it may be well to em- phasize the fact that the growing of suitable legumes, such as cowpeas, soybeans, and vetches, in a suitable cropping system with cotton and feed crops is good farm practice. The legumes if used properly aid in main- taining the organic matter and nitrogen in the soil. The summer-growing legumes are more valuable when they are used for grazing and the result- ing residues are plowed under for soil improvement, than when used exclu- sively for soil improvement, because both the feeding value and soil- improving value are utilized. Winter-growing legumes, such as hairy vetch and Austrian winter peas, may be grown to advantage for green manure in the eastern part of the State. The plowing under of non- legume plant residues, such as cotton stalks, corn stalks, weeds, and grass will also improve the land by adding vegetable matter, but the practice will not actually increase the amount of nitrogen in the soil as it merely returns to the soil the nitrogen and other plant food which were taken up from the soil by the growing plants. The growing of suitable legumes provides valuable protein feed for the farm livestock and at the same time improves the land. The practice of plowing under both leguminous and non-leguminous crop residues in con- nection with a suitable cropping system will gradually improve the land so that larger amounts of fertilizers can be used with increasing profits. Location of the Work The fertilizer work is _conducted at the following places in the State: At the Main Station Farm, College Station, in east central Texas; Sub- station No. 1, Beeville, in southern Texas; Substation No. 2, Troup, in northeastern Texas; Substation No. 3, Angleton, in the Gulf Coast Prairie; Substation No. 5, Temple, in the Blackland Prairie; Substation No. 6, Den- ton, on the Grand Prairie in central north Texas; and at Substation No. 11, Nacogdoches, in the “red lands” of eastern Texas. A brief statement of the soil types and climatic conditions is given in the discussion of the work at each station. EXPERIMENTAL RESULTS The results obtained in the fertilizer experiments are discussed sepa- rately for each station as a matter of convenience. Results Obtained on Kirvin Fine Sandy Loam at Troup The Kirvin fine sandy loam soil has responded to applications of nitro- gen, of phosphoric acid, and of potash. On the basis of the results obtained 10 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION at Substation N0. 2, Troup, during the‘ four years, 1927, 1928, 1929, and 1930, the use of 200 to 400 pounds per acre of a 4-6-4 or a 4-8-4 fer- tilizer, or a fertilizer furnishing similar ratios and amounts of plant food is suggested for cotton on the Kirvin soils. The Kirvin fine sandy 10am is a grayish sandy surface soil underlain by a stiff, plastic red clay subsoil. The Kirvin soils occupy extensive areas in northeastern Texas. The soil on which the fertilizer work was con- ducted contains .049 per cent of nitrogen, .039 per cent of phosphoric acid, 30 parts per million of active phosphoric acid, and 134 parts per: million of active potash in the surface soil, according to analyses made by the Division of Chemistry. The average yearly rainfall at Troup was 42.86 inches during" the 26 years, 1905 to 1930, inclusive. The rainfall for 1927, 1928, 1929, and 1930 was 42.74, 44.98, 41.75, and 45.90 inches, respectively. The rainfall is fairly well distributed during the months of the year, although in individual years the distribution is much less uniform, and periods of drought, or deficient rainfall, frequently occur during June, July, and August. The distribution of rainfall during the growing season has a greater influ- ence than the total rainfall on the yield of cotton. The variation in yield from year to year was due largely to differences in distribution of rainfall. A two-year rotation of cotton and corn has been used in these studies, the fertilizers being applied to both crops. Nitrogen: The Kirvin fine sandy loam is somewhat deficient in nitrogen. The 4-12-4 fertilizer made an average yield of 248 pounds of lint per acre for the four years of the experiment, as compared with a yield of 200 pounds for the 0-12-4 fertilizer (Table 1). This is an average increase of 48 pounds of lint, which may be attributed chiefly to the 4 per cent of nitrogen (16 pounds) in the 4-12-4 fertilizer, although the presence of phosphoric acid in connection with the nitrogen was responsible for some of the increase. The 4 per cent of nitrogen apparently furnished enough nitrogen for cotton on the Kirvin fine sandy loam, since larger amounts did not produce significant increases in yield. There was practically no dif- ference in the yield of cotton where all of the nitrogen in the fertilizer was supplied in sulphate of ammonia and where two-thirds was supplied in sulphate of ammonia and one-third in cottonseed meal. Phosphoric Acid: The soil responded to applications of phosphoric acid. The 4-6-4 fertilizer produced an average yield of 254 pounds of lint per acre, or 55 pounds more than the yield of the fertilizer which contained no phosphoric acid (the 4-0-4 fertilizer), as shown in Table 1. This increase of 55 pounds of lint is attributed largely to the 24 pounds of phosphoric acid in the 4-6-4 fertilizer, and is about two and one-fourth pounds of lint for each pound of phosphoric acid applied. Further increases in the per- centage of phosphoric acid made no additional increases in the yield of cotton. It is concluded from these data that 6 to 8 per cent of phos- phoric acid in 400 pounds of fertilizer, or 24 to 32 pounds of phosphoric FERTILIZER EXPERIMENTS WITH COTTON 11 acid, is enough phosphoric acid with the nitrogen and potash used, for cotton on this particular soil. Applications of potash increased the yield of cotton on the Potash : Kirvin fine sandy loam. The 4-12-4 fertilizer made an average yield of 248 pounds of lint per acre, while the fertilizer which contained no potash (the 4-12-0 fertilizer) produced only 224 pounds (Table 1). The 16 pounds TABLE 1—Yield per acre in pounds 0f lint cotton at Troup, Texas, 1927 to 1930, when 400 pounds of fertilizers of different analyses were applied and when a 4-12-4 fertilizer was applied at different rates per acre AverageI Average increase Fertilizer used 1927 I 1928 I 1929 I 1930 produced by . I fertilizer I lbs. lbs. I lbs. I lbs. I lbs. I lbs. N0 fertilizer ....................... .__I 294 I 207 I 132 I 128 I 190 ' Nitrogen varied: I I I 294 210 139 155 200 I 1O 347 255 210 I 178 248 I 58 349 I 258 215 165 247 57 345 I 258 206 179 I 247 I 57 '*~~ 8-12-4 _._‘. ........................ _- 353 267 229 170 I 255 I 65 Phosphoric acid varied I 294 212 142 148 I 199 9 347 I 254 226 187 254 64 359 240 224 178 250 60 347 255 210 178 248 58 4-12-0 ............................. .. 324 240 177 153 224 34 ' 341 235 181 168 231 41 s47 255 210 17s I 24s 5s Rates of 4-12-4: I I I 200 lbs _________________________ .. 327 221 188 168 I 226 36 400 lbs..__ _ 347 I 255 210 178 I 248 I 58 600 lbs.“ 358 I 269 242 194 I 266 76 800 lbs. ___________________________ __ 365 I 266 I 239 178 I 262 72 I *One-third of ammonia. of potash in nitrogen was supplied in cottonseed meal and two-thirds in sulphate of the 4-12-4 fertilizer, in the presence of the nitrogen and phosphoric acid, made an average increase of 24 pounds of lint per acre, or one and one-half pounds of lint for each pound of potash used. The average yield of cotton increased as the rate of application of the 4-12-4 fertilizer was increased from 200 The 800-pound application, It will be noted that the smaller applications were relatively more efficient than the larger appli- cations. For example, in Table 2, it is shown that the use of 200 pounds of fertilizer made an increase of 36 pounds of lint, or 18 pounds of lint for each 100 pounds of fertilizer, While the use of 800 pounds of fer- tilizer produced an increase of 72 pounds of lint, or only 9 pounds of lint for each 100 pounds of fertilizer used. Thus it is seen that the yield of cotton increased with the rate of application of fertilizer but the efficiency of the fertilizer decreased as the rate was increased. Rates of Application of Fertilizer: to 600 pounds per acre, as shown in Table 1. however, made no further increase in yield. Omission of One Element Reduces Effectiveness of Fertilizer: It should not be inferred from the preceding discussion that the increase in yield produced by a complete fertilizer would be the sum of the increase pro- 12 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION duced separately by the nitrogen, by the phosphoric acid, and by the potash. The yields of cotton obtained indicate that all three elements— nitrogen, phosphoric acid, and p0tash——must be present to secure the TABLE 2.—Average increase in yield of lint produced by the 4-12-4 fertilizer used at different rates per acre and increase in yield of lint per 100 pounds of fertilizer used at Troup, Texas, 1927 to 1930 Increase in yield- l l Rate per acre l Average yield l Increase over un- l produced by pounds per acre l fertilized soil l 100 pounds of fertilizer l Lbs. lint l Lbs. lint l Lbs. lint 190 l 226 36 ‘, 18 248 58 15 266 76 13 800 262 72 i 9 greatest effect of the fertilizer. Or, stated in another way, the omission of either one of the three elements renders the fertilizer less_effective. This is shown clearly by the following comparisons: Yield in pounds Treatment of lint None 190 O-12-4 200 4- 0-4 199 4-12-0 224 4-12-4 248 It will be noted from the above figures that the addition of either nitro- gen or phosphoric acid without the other does not increase the yield appre- ciably, which indicates that the soil is equally deficient in both elements, which must be used together for satisfactory results. Fertilizers Suggested for the Kirvin Soils: From the results obtained at Troup the use of 200 to 400 pounds per acre of a 4-6-4 or 4-8-4 fertilizer or fertilizer furnishing similar amounts and ratios of plant food is sug- gested for the average Kirvin soils of the region. Under more favorable conditions, that is on more productive soils, larger amounts may be used to advantage. Results Obtained on the “Red Lands” at Nacogdoches The experimental plats, consisting mostly of small areas of Ruston Orangeburg, and Nacogdoches fine sandy loams intermingled, at Nacog- doches have responded readily to applications of phosphoric acid and nitro- gen and to some extent to applications of potash. Phosphoric acid, how- ever, appears to be needed before either nitrogen or potash for the pro- duction of cotton on this soil. On the basis of the results obtained at Substation No. 11, Nacogdoches, during the five years 1927 to 1931, inclu- sive, the use of 200 to 400 pounds per acre of a 4-6-4 or 4-8-4 fertilizer or z fertilizer carrying somewhat similar amounts and ratios of plant food i: suggested for cotton on the Nacogdoches and associated soils. FERTILIZER EXPERIMENTS WITH COTTON 13 The land on which the fertilizer Work was conducted consists princi- pally of Nacogdoches, Norfolk, and Orangeburg fine sandy loams inter- mingled. The Nacogdoches soils are typically red in color, and are the main soils of the so-called “Red Lands” in the eastern part of the State. The topography is rolling to hilly and consequently the soils under cul- tivation are subject to serious erosion unless protected by suitable ter- races. The soil used in the experiment contained .026 per cent of nitrogen, .038 per cent of phosphoric acid, 17 parts per million of active phosphoric acid, and 140 parts per million of active potash, according to analyses made by the Division of Chemistry, Texas Agricultural Experiment Station. A three-year rotation of cotton, corn, and_cowpeas is used in the experi- ment. Fertilizer has been applied to the cotton and corn only, the coWpeas receiving the residual effects of the fertilizer. The coWpeas have been harvested for seed and the vines. plowed under for soil improvement. The average annual rainfall at Nacogdoches during the 19 years, 1913 i to 1931, inclusive, was 48.58 inches. The annual rainfall in 1927, 1928, 1929, 1930, and 1931 was 45.72, 39.99, 49.65, 48.77, and 50.15 inches, re- TABLE 3.-~Yield of cotton in pounds of lint per acre at Nacogdoches, Texas, 1927 to 1931, when 400 pounds of fertilizers of different analyses were used and when a 4-12-4 fertilizer was applied at different rates per acre | l | l j Average increase Fertilizer used | 1927 I 1928 1929 1930 i 1931 ‘Averagel produced by l | fertilizers l l l l l None ................... 1 141 l 171 l 82 103 102 120 _... 8-12-8 (800 lbs.) 197 240 209 . . . 1 _ _ _ _ _ . .. 21.5** .__- Nitrogen varied: l 0-12-4 ........ .. 143 242 92 200 138 163 43 i.‘ 4-12-4 ________ .. 159 298 169 142 204 194 74 4*-12-4 ...... __ .171 323 187 132 190 201 81 -? 6-12-4 . 196 I 280 148 176 211 202 82 i‘ 8-12-4 ......... _. i 195 , 304 174 140 220 207 87 Phosphoric acid I varied: 4-0-4 129 103 52 105 116 101 -——19 “"-' 4-6-4 185 281 161 121 206 191 71 "“’ 4-8-4 _. 149 266 182 161 253 202 82 4-12-4 .......... 1 1.59 298 169 142 204 194 74 Potash varied: I , 4-12-0 153 275 130 192 252 200 80 -'-— 4-12-2 .._ 171 271 149 200 181 194 74 4-12-4 __________ 1 [ 159 298 169 l 142 204 194 74 Rates of 4-12-4: 200 lbs. ________ __ 130 330 133 173 168 187 67 400 lbS. 159 298 169 142 204 194 74 600 lbs. __... 161 328 180 137 257 213 93 800 lbs. . ...... 1 184 287 180 112 297 212 92 Manure: 8 tons ....... 1 ‘ 181 280 212 ____ .. 224*“ ___. 12 tons 167 342 256 _ . . _ _ _ _ . _ _. 255** -__- 12 tons and ' 400 lbs. super- phosphate ..... .. 149 369 263 _ . _ _ . _ . . . _ _. 260“ *One-third of nitrogen supplied in cottonseed meal and two-thirds in sulphate of ammonia. “Average for 1927, 1928, and 1929. spectively. ' While the average monthly rainfall is fairly uniform, periods of deficient rainfall sometimes occur in July or August which reduce the yield of crops. ' 14 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION The yields of cotton for each year and the average yield for the five years, 1927 to 1931, are given in Table 3. The effect of various amounts of nitrogen, phosphoric acid, potash, and rates of application of the 4-12-4 fertilizer are discussed separately as a matter of convenience. Phosphoric Acid: As mentioned above, the soil responded to applica- tions of phosphoric acid, which seems to be the first limiting element for the production of cotton on this soil. The 4-8-4 fertilizer made an average yield of 202 pounds of lint per acre for the five years, or twice as much as the fertilizer which contained no phosphoric acid (the 4-0-4 analysis) (Table 3). The 32 pounds of phosphoric acid in the 400 pounds of the 4-8-4 fertilizer, therefore, produced 101 pounds of lint, or about 3 pounds of lint for each pound of phosphoric acid applied. Larger amounts of phosphoric acid did not produce further increases in yield, a fact which indicates that two parts of phosphoric acid to one part of nitrogen is a good ratio of these two plant foods on this soil. Nitrogen: Applications of nitrogen increased the yield of cotton to some extent but not nearly as much as did phosphoric acid. The 4-12-4 fertilizer gave an average yield of 194 pounds of lint for the five years, or 31 pounds more than the fertilizer which contained no nitrogen (the 0-12-4 analysis), as shown in Table 3. This gain of 31 pounds is attributed to the 16 pounds of nitrogen in the 400 pounds of the 4-12-4 fertilizer or about 2 pounds of lint for each pound of nitrogen applied. The 16 pounds of nitrogen apparently is a sufficient amount of nitrogen because larger amounts, 6 and 8 per cent, did not produce additional significant increases in yield of cotton. Potash: The soil responded to applications of potash three of the five years. In 1931, however, the 4-12-0 fertilizer made a considerably larger yield than the fertilizer containing potash, which raised its average yield slightly above the average yields of the 4-12-2 and 4-12-4 analyses (Table 3). The results, while not conclusive, indicate that the soil needs some potash, and 4 per cent of potash is suggested. Rates of Application of Fertilizer: The yield of cotton increased as the rate of application of the 4-12-4 fertilizer was increased up to 600 pounds TABLE 4.—Average increase in yield of lint produced by the 4-12-4 fertilizer applied at different rates and increase per 100 pounds of fertilizer at Nacogdoches, Texas, 1927 to 1931, inclusive Increase in yield Rate per acre Average yield Increase over un- produced by pounds per acre fertilized soil 100 pounds of fertilizer I Lbs. lint I Lbs. lint Lbs. lint None _ . ................................. _. 120 200 ............................................ .. 187 67 33,5 400 _______________________________________ .. 194 74 18,5 600 ______________________________________ .. l 213 93 15,5 800 ....................................... ..| 212 92 | 11,5 ' I per acre, as shown in Table 4. The yield produced per 100 pounds of fer- tilizer, however, decreased as the rate of application increased. The 200- FERTILIZER EXPERIMENTS WITH COTTON 15 pound application made a gain of 67 pounds of lint, or 33.5 pounds of lint for each 100 pounds of fertilizer used, while the yield gradually decreased to 11.5 pounds of lint for each 100 pounds of fertilizer where 800 pounds of fertilizer was used. Manure: Manure was used at the rate of 8 tons and 12 tons per acre in 1927, 1928, and 1929 but its use was discontinued thereafter. During the three years, the 8 tons and the 12 tons of manure produced average gains of 93 pounds and 124 pounds of lint, respectively, over the yield of the unfertilized soil. Each ton of manure in the 8-ton application produced on the average about 11 pounds of lint and in the 12-ton application, about 10 pounds of lint. The addition of 400 pounds of superphosphate "to the 12 tons of manure made a slight but not profitable increase in the yield of cotton. Fertilizers Suggested for the Nacogdoches and Ruston Soils: On the basis of the results obtained at Nacogdoches, a 4-8-4 or 4-6-4 fertilizer used at the rate of 200 to 400 pounds per acre or a fertilizer furnishing equiva- lent amounts and proportions of plant food is recommended for the Nacog- doches, Ruston, and associated soils of the region. Results Obtained on the Lake Charles Soils at Angleton The Lake Charles soils are deficient in phosphoric acid for the produc- tion of cotton, as indicated by the results of fertilizer experiments on these soils at Substation No. 3, Angleton. The use of 100 pounds of super- phosphate, or 200 to 600 pounds of a 4-8-0 fertilizer per acre is suggested for the Lake Charles soils. Some potash may be beneficial where larger amounts of nitrogen and phosphoric acid are supplied. Some of the higher- analysis fertilizers, such as the ammonium phosphates, in quantities to supply the above amounts and ratios of nitrogen and phosphoric acid also should give satisfactory results on the soils. The Lake Charles soils occupy extensive areas in the humid part of the Gulf Coast Prairie. They are black to dark-gray in color, with dark-gray heavy clay subsoils. These soils are very hard when dry although they crumble to fairly good tilth when plowed and cultivated at the proper mois- ture content. The topography is almost flat and drainage is slow. When the soils are adequately drained, however, they are rather productive. The fertilizer Work has been conducted on the Lake Charles clay. According to analyses made by the Division of Chemistry, the surface soil contains .117 per cent of nitrogen, .028 per cent of phosphoric acid, 20 parts per million of active phosphoric acid, and 210 parts per million of active potash. These experiments have been conducted in a three-year rotation of cot- ton, corn, and cowpeas, and in a three-year rotation of cotton, cotton, and corn. The cotton and corn were fertilized, while the cowpeas were not fertilized but received the-residual effects of the fertilizer. The average rainfall at Angleton for the 18 years, 1914 to 1931, inclu- sive, was 45.31 inches. The rainfall in 1930 and in 1931 was 43.16 and 40.18 inches, respectively. 16 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION The fertilizer work at Angleton was started in 1925.1 The work con- ducted during the five-year period, 1925 to 1929, inclusive, was not very comprehensive; the main object was to determine what element or elements are deficient in the soil. Sulphate of ammonia, superphosphate, and muriate of potash were used alone and in combination at two different rates. The treatments used (expressed in terms of nitrogen, phosphoric acid, and pot- ash) and the results obtained during the five years are given in Table 5. The results show rather definitely that the soil responded readily to appli- cations of superphosphate alone and in combination with nitrogen or potash. TABLE 5.——-Yield of cotton in pounds of lint per acre at Angleton, Texas, 1925 to 1929, where fertilizers of different analyses were used at 400 and 800 pounds per acre , i I | Average increase Fertilizer used 1925 r 1926 l 1927 z 1928 I 1929 Average] produced by | fertilizers I I - None .................. _. 282 173 I 508 289 70 264 At 400 pounds per acre 5-0-0 231 200 530 317 81 272 8 0-8-0 ............. .. 287 222 609 366 85 314 50 0-0-5 _____________ _, 234 162 442 303 44 237 -—27 5-8-0 A 283 216 591, 318 56 293 29 5 5 268 180 490 308 77 265 1 0 5 349 191 575 327 77 304 40 5 5 351 187 648 364 45 319 55 5-0-0 310 222 498 261 158 290 26 0-8-0 412 202 540 298 127 316 52 0-0-5 ............ 1 364 176 497 293 130 292 28 5-8-0 ............ .1 459 23] 657 317 124 358 94 5-0-5 V l 369 192 551 348 159 324 60 0-8-5 _______ 399 196 566 327 155 _ 329 65 s-s-s ., ‘ 400 I 321- "103 o s73 132 | sse 122 For instance, the use of 400 pounds per acre of the 0-8-0 fertilizer (the same as 200 pounds of 16 per cent superphosphate) made an average yield of 314 pounds of lint per acre, or 50 pounds more than the unfertilized soil. In all cases, the analyses used at the rate of 800 pounds per acre made larger average yields than the same. analyses applied at the rate of 400 pounds per acre. Apparently the use of commercial nitrogen in this test did not produce as large increases in yield as did similar amounts of nitrogen in the test dur- ing 1930 and 1931. This difference may be due to the fact that cowpeas were plowed under ‘every third year on the soil used in the test from_ 1925 to 1929 and supplied part of the nitrogen required by the crop. While the results obtained during the five years, 1925 to 1929, inclusive, indicated that phosphoric acid is the first limiting element in the produc- tion of cotton on the Lake Charles soil, they gave no definite information on the proper ratio of plant food and rate of application of fertilizer for cotton under the particular conditions. In viewf of this fact, the experiment was revised and expanded consid- erably in 1930 to determine definitely the fertilizer requirements of the soil for the production of cotton. The several treatments used and the results obtained in 1930 and 1931 are shown in Table 6. FERTILIZER EXPERIMENTS WITH COTTON 17 Phosphoric Acid: All applications of phosphoric acid increased the yield of cotton. The 0-4-O fertilizer (100 pounds of 16 per cent superphosphate) produced an average yield of 330 pounds of lint per acre, or 60 pounds more TABLE 6.—-Yield of lint cotton in pounds per acre at Angleton, Texas, 1930 and 1931, where 400 pounds of fertilizers of different analyses were used and where a 4-12-4 fertilizer was used at different rates per acre i Average increase Fertilizer used ' I 1930 ‘ 1931 yAveragel produced by fertilizers None 249 290 270 .... __ Nitrogen varied: 0-12-4 372 376 374 104 4-12-4 _____________________________________________________ ._ 1 390 421 406 136 6-12-4 _| 394 448 421 151 8-12-4 .................................................... 1 | 409 476 443 173 Phosphoric acid varied : 0-4-0 ..... ._ 347 4 312 330 60 0-8-0 .................................................... W 319 368 344 74 4-0-4 _. ........ 1 283 l 329 306 36 4-6-4 381 392 387 117 4-8-4 ..... 388 1 409 399 129 4-12-4 -_ ...... .. 390 421 406 136 4-16-4 ........................................................... 1 401 I 419 410 140 Potash varied: 4-12-0 ............................................................. .. 384 386 385 115 4-12-4 390 421 406 136 4-12-6 ,,,,,, 1 387 358 373 103 At 800 lbs. per acre: 4-12-4 ....................................................... , 1 1 457 503 480 210 6-12-4 W. . _ 466 550 508 238 8-12-4 522 I 561 | 542 272 10-12-4 ......................................................... 1 521 624 \ 573 303 8-12-4 522 f 561 542 272 8-12-6 ................................................ ._ , __________ .1 524 579 552 282 s-12-s ...................................... _______________ ., 530 l‘ 576 55s 223 Rates of 4-12-4: 200 s51 l 383 367 97 400 ............................................................. .. 390 421 406 136 600 __ | 412 461 437 167 800 ........................................................ 1177*] 457 I 503 480 210 1000 ........................................................ _. | 476 | 54s i 512 242 than the unfertilized soil, for the two years, 1930 and 1931 (Table 6). The 4-6-4 fertilizer made an average yield of 387 pounds of lint per acre, which was a gain of 81 pounds over the yield of the fertilizer which contained no phosphoric acid (the 4-O-4 analysis). The yield of cotton increased as the percentage of phosphoric acid was increased from 6 to 16 per cent. Where the fertilizer was used at the rate of 400 pounds per acre the yields indi- cate that 8 per cent of phosphoric acid is sufficient where only 4 per cent of nitrogen is used, as additional amounts of phosphoric acid produced only small increases in yield. - Nitrogen: The yield of cotton increased as the percentage of nitrogen was increased from 0 to 8 per cent. The 4-12-4 fertilizer produced an average yield of 406 pounds of lint per acre, or 32 pounds more than the 0-12-4 fertilizer. The use of 6 per cent of nitrogen increased the yield 47 pounds, and 8 per cent of nitrogen, 69 pounds of lint. The results indicate that the soil will respond to even larger applications of nitrogen. For in- - stance, where 800 pounds of fertilizer was used and the percentage of nitro- 18 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION gen ranged from 4 per cent to 10 per cent, the yield of cotton increased with each additional increment of nitrogen. Potash: In general, applications of potash did not produce consistent in- creases in the yield of cotton. The 4-12-0 fertilizer, however, made an average yield of 385 pounds of lint and the 4-12-4 fertilizer 406 pounds, for the two years, 1930 and 1931, which is a gain of 21 pounds attributable to the 4 per cent of potash (Table 6). The 4-12-6 fertilizer yielded only 373 pounds of lint, or slightly less than the 4-12-0 fertilizer. Increasing the potash from 4 per cent to 8 per cent where 800 pounds of fertilizer was used did not produce significant increases in yield. Rates of Application of Fertilizer: The 4-12-4 fertilizer was applied at rates of 200, 400, 600, 800, and 1,000 pounds per acre. The yield of cotton increased from 367 pounds to 512 pounds of lint as the rate of applica- tion was raised from 200 to 1,000 pounds per acre (Table 6). The first increment of 200 pounds of fertilizer produced an increase of 97 pounds of lint; the second 200 pounds of fertilizer, 39 pounds of lint; the third increment of 200 pounds of fertilizer, 31 pounds of lint; the fourth, 200 pounds of fertilizer, 43 pounds of lint; and the fifth increment of 200 pounds TABLE 7.~Average increase in yield of lint produced by the 4-12-4 fertilizer applied at different rates and increase per 100 pounds of fertilizer used at Angleton, Texas, 1930 and 1931 Increase in yield l Rate per acre Average yield Increase over un- produced by pounds per acre fertilized soil 1 100 pounds of fertilizer Lbs. lint Lbs. lint a Lbs. lint 270 ] 367 97 48.5 406 136 34.0 437 167 27.8 480 l 210 26.2 512 I 242 ' 24.2 of fertilizer, 32 pounds of lint. The amount of lint produced by each 100 pounds of fertilizer decreased rather sharply as the rate of application in- creased, as shown in Table 7. The yield per 100 pounds of fertilizer de- creased from 48.5 pounds of lint to 24.2 pounds of lint when the rate of application was increased from 200 to 1,000 pounds per acre. Fertilizers Suggested for the Lake Charles Soils: The results of the fer- tilizer experiments at Angleton indicate that the use of 100 pounds of superphosphate, or 200 to 600 pounds of a 4-8-0 fertilizer, is good fer- tilizer practice for cotton on the Lake Charles soils. Where larger amounts of nitrogen and phosphoric acid are used, the addition of potash may be beneficial, especially on the lighter soils. The use of some of_ the commer- cial ammonium phosphates in quantities to supply the above amounts and ratios of plant food also should be satisfactory. FERTILIZER EXPERIMENTS WITH COTTON 19 Results Obtained on Lufkin Fine Sandy Loam at College Station The Lufkin fine sandy 10am at College Station gave better response "to applications of phosphoric acid and potash than to applications of nitrogen. The results obtained during the five years, 1927 to 1931, inclusive, indi- cate that the use of 200 to 400 pounds per acre of an 0-12-4 or 4-12-4 fertilizer or a fertilizer furnishing similar ratios and amounts of plant food is good fertilizer practice for cotton on the Lufkin soils. The Lufkin fine sandy loam soil is one of the most extensive soil types‘ of the region. The surface soil is gray in color and is underlain by a gray or mottled grayish and yellowish dense plastic clay subsoil. The Lufkin soils, on account of the dense subsoil, have slow under-drainage and on the smooth flat areas the soils may remain wet for a long time after rains. They are only moderately productive. The soil on which the fertilizer work is conducted contains .065 per cent of nitrogen, .024 per cent of phos- phoric acid, 49 parts per million of active phosphoric acid (equivalent to 98 pounds in the 2,000,000 pounds of soil in the upper 6 2-3 inches of soil TABLE 8.-—Yield of cotton in pounds of lint per acre at College Station, 1927 to 1931, when 400 pounds of fertilizers of different analyses were applied, and where a 4-12-4 fertilizer was used at different rates per acre. | | Average increase l l Fertilizer used l| 1927 l 1928 I 1929 I 1930 l 1931 lAverageI produced by I l | l l I | fertilizers l l l l l l None __________________ .. 206 I 315 122 219 287 230 8-12-8 (800 lbs.)_f 288 l 391 187 303 301 294 64 Nitrogen varied: | 0-12-4 __________ __ 218 375 210 293 364 292 62 4-12-4 _ . 236 l 397 191 l 295 367 297 67 4*-l2-4... . 254 ] 371 l 126 280 423 291 61 6-12-4 ........ .. 229 i 375 199 310 345 292 62 8-12-4 . 228 352 164 280 354 276 46 Phosphoric acid varied: 4-0-4 ............ a 203 341 106 241 342 247 17 4-6-4 ............. _. 228 365 150 2'36 365 281 51 4-8-4 ............. .. 240 382 140 282 285 286 56 4-12-4 ........... ._ 236 397 191 295 367 297 67 Potash varied: -12-0 194 359 141 258 278 246 16 4-12-2 221 378 152 290 346 277 47 4-12-4 236 397 191 295 367 297 67 Rates of 4-12-4: J 200 lbs. 22 382 126 273 373 275 45 400 lbs. 236 397 191 295 367 297 67 600 lbs..._-_.._.. 236 381 188 305 351 292 62 800 lbs. ....... .. 266 408 184 313 353 305 75 Manure: i 8 tons ........... .. 237 l 366 190 281 402 295 65 12 tons ........... _. 297 ' 394 169 311 391 312 82 12 tons and 400 lbs. super- phosphate ...... .. 282 439 I 223 343 433 344 114 *One-third of nitrogen supplied in cottonseed meal and two-thirds in sulphate of ammonia. per acre), and 48 parts per million of active potash in the surface- soil, according to analyses made by the Division of Chemistry. The fertilizer work was conducted in a three-year rotation of cotton, corn, and oats, the fertilizer being applied to each crop in the rotation. 20 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION The average yearly rainfall at College Station for the 43 years'1889 to 1931, inclusive, was 38.33 inches. The rainfall in 1927, 1928, 1929, 1930, and 1931, during which time the experiment was conducted, was 41.28, 34.34, 48.40, 44.27, and 34.79 inches, respectively. The average yearly rainfall would appear to be sufficient for satisfactory yields of crops, but the dis- tribution of the rainfall during the growing season and from year to year is not always favorable for the production of satisfactory yields of cotton and other crops. Periods of deficient rainfall frequently occur in July and August, resulting in low yields. ' The yields of cotton obtained in the experiment during the five years 1927 to 1931, inclusive, are given in Table 8. Phosphoric Acid: The Lufkin soil responded readily to applications of phosphoric acid. For example, the plats treated with the 4-12-4 fertilizer produced an average yield of 297 pounds of lint per acre during the five years of the experiment, which was 50 pounds more than the average yield of the plats which received the 4-0-4 fertilizer (Table 8). Or stated in another way, the 12 per cent of phosphoric acid in the fertilizer was responsible for the average increase of 50 pounds of lint per acre. Potash: The yield of cotton increased as the amount of potash was in- creased, as shown by the results presented in Table 8». The 4-12-4 fer- tilizer made an average yield of 297 pounds, or an increase of 51 pounds over the yield of the plats which received the 4-12-0 fertilizer. This gain of 51 pounds is attributed to the 4 per cent of potash. Nitrogen: The soil responded slightly to applications of nitrogen but the use of 4 per cent, or 16 pounds, of nitrogen in the 400 pounds of fer- tilizer was sufficient since larger amounts did not produce additional in- creases in yield (Table 8). Rates of Application of Fertilizer: The yield of cotton increased as the rate of application of the 4-12-4 fertilizer was increased from 200 pounds to 800 pounds per acre (Table 8). The application of 200 pounds per acre made an average yield of 275 pounds of lint per acre for the five years of TABLE 9.~Average increase in yield of lint produced by the 4-12-4 fertilizer used at dif- ferent rates and average increase per 100 pounds of fertilizer at College Station, 1927 to 1931 Increase in yield l Rate per acre l Average yield Increase over un- produced by pounds per acre fertilized soil 100 pounds of l l fertilizer l Lbs. lint l Lbs. lint l Lbs. lint l 230 ._ l 275 45 22.5 297 67 16.7 l 292 S 62 | 10.3 | 305 75 l 9.4 l I I the experiment, or 45 pounds per acre more than the yield of the soil which received no fertilizer. While larger amounts of fertilizer produced further increases in yield, the increases were not profitable. The increase FERTILIZER EXPERIMENTS WITH COTTON 21 produced per 100 pounds of fertilizer used gradually decreased from 22.5 pounds to 9.4 pounds as the rate was increased from 200 to 800 pounds per acre, as shown in Table 9. Manure: Manure was used alone at rates of 8 tons and 12 tons per acre and at 12 tons per acre in combination with 400 pounds of superphosphate. The application of 8 tons of manure made an average yield of 295 pounds of lint, or 65 pounds per acre more than the yield of the-unfertilized soil, as reported in Table 8. The treatment of 12 tons of manure and 400 pounds of superphosphate produced an average yield of 344 pounds of lint per acre while the use of 12 tons of manure alone produced 312 pounds, a’ differ- ence of 32 pounds. This gain, while indicating the value of superphosphate in balancing the plant-food content of manure, was not profitable. Fertilizers Suggested for Cotton on Lufkin Soil: On the basis of the re- sults obtained in the fertilizer work at College Station, the use of 200 to 400 pounds per acre of an 0-12-4 or a 4-12-4 fertilizer, or a fertilizer with equivalent amounts and ratios of plant food is suggested for the Lufkin fine sandy loam soil. Results Obtained on the Goliad Soils at Beeville The results of experiments with fertilizers on the Goliad fine sandy clay loam at Substation No. 1, Beeville, indicate that the soil is somewhat defi- cient in available phosphoric acid. In general, however, the use of fer- tilizers has not been profitable on this soil. The soils on the experiment station farm at Substation No. 1, Beeville, consist mostly of the Goliad series, which are dark calcareous soils. The fertilizer work has been conducted on the Goliad fine sandy clay loam. The surface soil contains .093 per cent of nitrogen, .032 per cent of phosphoric acid, 56 parts per million of active phosphoric acid, and 435 parts per million of potash, according to chemical anaylses made by the Division of Chemistry. These soils are naturally productive. The average yearly rainfall at Beeville was 30.56 inches for the 28 years, 1904 to 1931. The rainfall during the active growing season was 15.50 inches in 1927, 19.38 inches in 1928, 23.02 inches in 1929, 14.99 inches in 1930, and 21.53 inches in 1931. The experiment has been conducted in a three-year rotation of cotton, corn, and cowpeas. The fertilizers were applied in the drill to the cotton and corn. The cowpeas were grown for seed and the vines were plowed under for soil improvement. Studies with fertilizers on cotton have been conducted at Beeville since 1925. The experiments conducted in 1925 and 1926, however, were prelim- inary and were designed to indicate the elements deficient in the soil. Sul- phate of ammonia, superphosphate, and muriate of potash were used alone and in combination at two different rates. The treatments used expressed in terms of nitrogen, phosphoric acid, and potash, and the yields of cotton obtained are shown in Table 10. The‘ results obtained during these two years indicate that the soil is deficient in phosphoric acid and slightly defi- cient in nitrogen. The use of 200 pounds of 16 per cent superphosphate 22 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION (equivalent to 400'pounds 0f an 0-8-0 fertilizer) produced an average yield of 263 pounds of lint per acre, or 74 pounds more than the yield of the soil which received no fertilizer. Further, all treatments which included phos- phoric acid increased the yield of cotton. While the work conducted in 1925 and 1926 showed that the soil responded to application of phosphoric acid, it did not indicate the ratio of plant food needed in the fertilizer or a desirable rate of application. For this reason, TABLE 10.—~Yield of cotton in pounds of lint per acre at Beeville, Texas, 1925 and 1926, where fertilizers of various analyses were applied at rates of 400 and 800 pounds per acre I f I Gain produced Fertilizer used d 1925 1926 ‘Average! by fertilizer None ,,,,,,, 1 i 131 247 189 ,,,, 1 At 400 pounds per acre: I - - ............................................................... ..[ 145 293 219 3o 0-8-0 _________________________________________ __ l 162 364 263 74 0-0-5 l 190 24o 215 2e 5-8-0 ______________________________________________________ N 205 390 298 109 5-0-5 139 261 200 11 0-8-5 187 217 202 13 5-8-5 ................................................................ n 172 374 273 84 At 800 pounds per acre: 5-0-0 _________________________________________________________ 1 | 211 235 223 34 0-8-0 ................................................................ .. 141 285 213 24 0-0-5 137 213 175 ——14 5-8-0 ___________________ .................................. V- 157 372 265 76 5-0-5 ____ 157 272 215 26 0-8-5 135 409 272 83 5-8-5 181 464 323 l 134 Y l the work was revised and expanded in the spring of 1927 with the view of determining definitely the fertilizer requirements of the soil for cotton. The results obtained with the several fertilizer treatments during the five years, 1927 to 1931, inclusive, are shown in Table 11. The effects of nitro- gen, of phosphoric acid, of potash, and of rates of application of fertilizer on the yield of cotton are discussed separately in order to show the proper amount of each element and the most suitable rate of application. Phosphoric Acid: The Goliad sandy clay loam has given some response to applications of phosphoric acid. For instance, the 4-6-4 fertilizer pro- duced an average yield of 348 pounds of lint per acre, or 54 pounds more than the fertilizer which contained no phosphoric acid (the 4-0-4 fertilizer). The 24 pounds of phosphoric acid, in combination with the nitrogen and potash, was responsible for the gain of 54 pounds of lint, which is equiva- lent to two and one-fourth pounds of lint for each pound of phosphoric acid used. These results indicate that 6 to 8 per cent is enough phosphoric acid for the soil. Apparently the addition of nitrogen and potash without phosphoric acid reduced the yield of cotton, since the 4-0-4 fertilizer made an average yield of 294 pounds of lint while the soil which received no fertilizer produced 322 pounds per acre. Nitrogen: The application of 4 per cent of nitrogen (16 pounds in the 400 pounds of 4-12-4 fertilizer) made an average yield of 330 pounds of lint,_or 34 pounds more than the yield of the 0-12-4 fertilizer (Table 11). FERTILIZER EXPERIMENTS WITH COTTON 23 This is an increase of about 2 pounds of lint cotton for each pound of nitro- gen used. Apparently the 4 per cent of nitrogen was sufficient, for larger amounts made only slight increases in yield, which were probably not significant. TABLE 11.—Yield of cotton in pounds of lint per acre at Beeville, Texas, 1927 to 1931, where 0 pounds of fertilizers of different analyses were used and where a 4-12-4 fertilizer was used at different rates per acre Average increase I I i I Fertilizer used l 1927 l 1928 1929 1930 1931 | Average! produced by [ | fertilizers i I l None ............... .. 146 [ 127 445 655 ~ 236 322 8-12-8 (800 lbs.) 108 113 503 679 272 335 13 Nitrogen varied: i 0-12-4 125 116 466 521 254 296 —26 4-12-4 146 132 476 616 278 330 8 4*-12-4 . . .. 178 140 490 630 272 342 20 6-12-4 ......... .. 121 100 429 584 299 307 ——15 8-12-4 _________ .. 157 135 484 682 293 350 28 Phosphoric acid l varied: I 4-0-4 129 167 364 586 222 294 ~28 4-6-4 191 128 481 662 277 348 26 4-8-4 135 143 501 626 239 329 7 4-12-4 .......... .. 146 132 476 616 278 330 8 Potash varied: 4-12-0 ........... .. 80 159 456 514 297 301 —-21 4-12-2 105 146 496 571 306 325 3 4-12-4 ............ .. 146 132 476 616 278 330 8 Rates of 4-12-4: 200 lbs. . ....... _. 131 137 I 453 663 271 331 9 400 lbs. ..... -. . 146 132 476 616 278 330 8 600 lbs.. ..... .. 132 119 451 705 296 341 19 800 lbs. _____ _. 105 123 504 692 279 341 19 Manure: | - 8 tons .......... . . . . . _ . . . . . _ . . . . . .. 671 299 485"‘ .2 tons . . . _ . . . . . . . . _ . _ . . . . . . . ._ 725 304 515“ -_.- 12 tons and \ 400 lbs. super- I phosphate .... _. l ____ ._ I .... ._ ll .... ., I 658 333 495*” *One-third of nitrogen supplied in cottonseed meal; two-thirds in sulphate of ammonia. “Average for two years, 1930 and 1931. Potash: The application of nitrogen and phosphoric acid Without potash apparently reduced the yield as compared with the yield of the unfertilized soil or with the yield of the soil which received the 4-12-4 fertilizer, as shown in Table 11. The 4-12-4 fertilizer, however, made an average yield of 330 pounds per acre, or only 8 pounds more than the yield of the un- fertilized soil, which probably was not significant. TABLE 12.——Average increase in yield of lint produced by the 4-12-4 fertilizer used at different rates and average increase of lint per 100 pounds of fertilizer at Beeville, 1927 to 1931 I Increase in yield Rate per acre Average yield Increase over un- produced by pounds per acre l fertilized soil 100 pounds of l fertilizer i Lbs. lint i Lbs. lint Lbs. lint 322 331 9 4.5 330 8 2.0 341 19 3.2 341 19 2.4 24 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION Rates of Application of Fertilizer: The yield of cotton increased as the rate of application of fertilizer was increased, although the increases were not profitable. The gain produced by the various rates ranged from 9 pounds of lint for the 200 pounds of fertilizer to 19 pounds of lint for the 800 pounds of fertilizer, as shown in Table 12. Manure: Manure was used in 1930 and 1931. The application of 8 tons of manure produced 485 pounds of lint, or 39 pounds more than the unfer- lized soil, which is a gain of nearly 5 pounds of lint for eachton of manure used. The 12 tons of manure made an average yield of 515 pounds of lint, which was 69 pounds more than the yield of the untreated soil and 30 pounds more than the yield of the 8 tons of manure. Results Obtained on the Houston Soils at Temple All of the fertilizers used increased the average yield of cotton on the Houston black clay and Houston clay at Temple during the four years, 1928 t0 1931. In general, however, the increases in yield were not suffi- cient to pay for the fertilizers used. The results indicate that the soil gives better response to applications of phosphoric acid than to applications of nitrogen or potash. Chemical analysis also indicates that the soil is defi- TABLE 13.—Yield in pounds of lint cotton per acre at Temple, Texas, 1928 to 1931, where 400 pounds of fertilizers of different analyses were applied and where a 4-12-4 fertilizer was used at different rates per acre I Average increase Fertilizer used ' 1928 1929 1930 1931 Average produced by l fertilizer None .................................... -. 183 162 99 303 187 8-12-8 (800 lbs.) ............... ._ 189 212 123 356 220 33 Nitrogen varied: 0-12-4 206 188 155 327 219 32 4-12-4 205 173 173 355 227 40 4*-12-4 198 193 119 338 212 25 6-12-4 267 194 144 _ 351 239 52 8-12-4 268 198 132 322 230 43; 220 142 114 311 197 10 222 188 128 339 219 32 222 171 117 335 211 24 205 173 173 355 227 40 U 214 187 146 310 214 27 217 164 141 363 221 34 205 l 173 173 355 227 40 190 179 99 328 199 12 205 173 173 355 227 40 214 I 198 113 383 227 40 800 lbs. .......................... _. 215 I 174 131 374 224 37 *One-third of nitrogen supplied in cottonseed meal; two-thirds in sulphate of ammonia. cient in active (available) phosphoric acid, although it contains an abund- ‘ ance of total phosphoric acid. The fertilizer work at Substation No. 5, Temple, is located on Houston clay and Houston black clay, which are the principal soil types in the Blackland Prairie in central Texas. The Houston soils, the well-known FERTILIZER EXPERIMENTS WITH. COTTON 25 “black waxy” soils, have been noted for their productiveness, as indicated by their high yield of good-quality cotton. The surface soil contains .101 per cent of nitrogen, .105 per cent of phosphoric acid, 7 parts per million of active phosphoric acid, and 67 parts per million of active potash, as shown by the analyses made by the Division of Chemistry. The average yearly rainfall at Temple for the 19 years, 1913 to 1931, inclusive, was 33.70 inches. The rainfall during each of the four years of the experiment was: 29.74 inches in 1928, 31.86 inches in 1929, 34.75 inches in 1930, and 23.93 inches in 1931. The experiment has been conducted in a three-year rotation of cotton, corn, and oats in which the fertilizer has been applied to each crop. The work was begun in 1928 and the results of four years are now available and are presented in Table 13. As mentioned above, all of the fertilizers used produced larger average yields than the unfertilized soil during the four“ years, 1928 to 1931, as shown in Table 13. The results indicate that probably phosphoric acid is needed before either nitrogen or potash. For example, the 4-12-4 fertilizer made an average yield of 227 pounds of lint, which was 30 pounds more than the yield of the fertilizer which contained no phosphoric acid (the 4-0-4 fertilizer). While the use of nitrogen made some increases in yield, as shown in Table 13, it is doubtful if they were significant. Somewhat similar results were obtained with potash. Although some increases in yield of cotton were obtained from the appli- cation of fertilizers on the Houston soils at Temple, the fertilizers Were, as a rule, not profitable. Results Obtained on the San Saba Soils at Denton Fertilizers have increased the yield of cotton to some extent on the San Saba clay at Substation No. 6, Denton, Texas. In general, however, the fertilizers used have not been profitable and consequently fertilizers are not recommended for cotton on this soil. The soils at Substation No. 6, Denton, belong to the Denton and San Saba series of soils, which are important and extensive soils of the Grand Prairie. The fertilizer work has been conducted on the San Saba clay, which has a black to dark-brown surface soil underlain by a dark-brown or yellowish- brown, or in places, by very dark-gray clay subsoil. The San Saba clay is a rather productive soil. According to a chemical analysis made by the Division of Chemistry, the surface soil contains .140 per cent of nitrogen, .076 per cent of phosphoric acid, 34 parts per million of active phosphoric acid, and 285 parts per million of active potash. The work with fertilizers has been conducted in a three-year rotation of cotton, corn, and wheat and in a three-year rotation of cotton, corn, and oats. These studies have been in progress since 1926. The work in 1926 and 1927, however, was rather limited in scope and the main object was to determine the elements deficient in the soil. Sulphate of ammonia, super- 26 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION phosphate, and muriate of potash were used alone and in all possible com- binations at two different rates. The treatments used, expressed in per- centages of nitrogen, phosphoric acid, and potash (N-P-K), and the results obtained are presented in Table 14. The average yields of cotton for the two years indicate that phosphoric acid is deficient in this soil. For ex- TABLE 14.—Yield of cotton in pounds of lintper acre at Denton, Texas, 1926 and 1927, where fertilizers of various analyses were used at 400 and 800 pounds per acre l I l Average increase Fertilizer used 1926 1927 Average] produced by fertilizers None m 262 277 270 At 400 lbs. per acre: 242 280 261 ——9 223 351 287 17 225 284 255 —¥15 266 385 326 56 177 347 262 ——8 237 395 316 46 291 372 332 62 206 268 237 ——33 315 428 372 102 292 363 328 58 300 464 382 112 225 330 278 8 316 S 413 365 95 285 485 385 115 TABLE 15.—Yield of cotton in pounds of lint per acre at Denton, Texas, 1928 to 1931, where 400 pounds of fertilizers of different analyses were applied and where a 4-12-4 fertilizer was used at different rates per acre. l ‘ l Average increase Fertilizer used 1928 l 1929 1930 l 1931 Averagel produced by l I fertilizer I l l l l l l I None __________________________________ .. 341 l 229 224 387 295 8-12-8 (800 lbs.) 381 I 249 242 410 321 26 Nitrogen varied: l 0-12-4 ........................... .. l 339 262 232 442 319 24 4-12-4 356 287 228 426 324 29 4*-12-4 347 300 247 404 325 30 6-12-4 _“ 354 291 226 425 324 29 8-12-4 ......................... __ 369 292 216 432 327 32 Phosphoric acid varied : | l l l 4-0-4 332 276 231 381 305 10 4-6-4 354 281 225 409 317 22 4-8-4 353 328 237 444 341 46 4-12-4 356 287 228 426 324 29 Potash varied: 4-12-0 338 | 267 212 407 306 11 4-12-2 339 261 216 422 310 15 4-12-4 356 287 228 426 324 29 Rates of 4-12-4: lbS.__.._..___._ -__-. _-._.-..> 331 288 235 431 321 26 400 lbs._ 356 287 228 426 324 29 600 lbsa_ 387 305 239 455 347 52 800 lbs. .......................... .. 357 288 232 390 317 22 Manure: 8 120115 _______________________ 383 266 251 490 348 53 12 t0nS ________________________ _, 377 292 247 437 338 43 12 tons and 400 lbs. I I superphosphate 366 l 295 I 252 409 I 331 36 *One-third of nitrogen supplied in cottonseed meal and two-thirds in sulphate of ammonia. FERTILIZER EXPERIMENTS WITH COTTON 27 ample, applications of phosphoric acid either alone or with nitrogen or potash made somewhat larger average yields than the unfertilized soil. The fertilizer studies were revised and enlarged in 1928 with the View of determining the most suitable analyses of fertilizer and the most prac- ticable rate of application of fertilizer for cotton under the conditions pre- vailing in the region. The results of the revised work during the four years, 1928, 1929, 1930, and 1931, are given in Table 15. All of the fertilizer treatments used made larger average yields of cot- ton than the soil which received no fertilizer. Applications of nitrogen, of phosphoric acid, and of potash have produced small increases in yield. The results obtained so far indicate that the 4-8-4 fertilizer furnishes about the right proportion of nitrogen, phosphoric acid, and potash. In general, however, the fertilizers have not been profitable when applied to cotton on the San Saba clay. l PROFITS OBTAINED FROM THE USE OF FERTILIZERS The profits resulting from the use of fertilizers on any crop will depend upon (1) the cost of the fertilizer, including the purchase price, interest on the money invested in fertilizer, the cost of applying the fertilizer, and the harvesting and preparing the increase in yield of crop produced by fertilizer; (2) the increase in yield and improvement in quality resulting from the fertilizer; and (3) the selling price of the crop. It is obvious from these considerations that the fertilizer which makes the largest yield may not be the most profitable fertilizer. In general, however, the best fertilizer to use will be the one that gives the largest and most consistent profit over a period of years. In order to arrive at the most profitable fertilizer practice for cotton, the profits or losses resulting from the use of the different fertilizers at the substations were computed. The profits and losses were obtained by de- ducting the cost of the fertilizer from the value of the increase in yield of cotton produced by the fertilizer. The figures on profit and loss do not include any interest on the money invested in fertilizer or the expense in- volved in applying the fertilizer to the land and picking and harvesting the increase produced by the fertilizer. The cost of the fertilizer during each year of the experiment was based on the average selling price of the ma- terials used in making up the various analyses. The average price of spot cotton, middling basis for 73-inch staple, for the month of October on the Houston market each year of the experiment was used in estimating the value of the increase produced by the fertilizer. The average profits obtained from the fertilizer used during the years of the experiment are given in Table 16. The reader should not get the im- pression that he Would obtain similar results if he were to use the same or similar fertilizers, because the cost of fertilizers and the selling price of cotton in all probability would be different from the ones used here. These figures are given merely to interpret to the fertilizer consumer the 28 BULLETIN NO. 469, TEXAS AGRICULTURAL EXPERIMENT STATION results of the fertilizers in dollars and cents, which in the final analysis, determines the proper practices to follow in any locality. If, however, the increase in yield caused by the fertilizer, the selling price of the crop, TABLE 16.——Average profits and losses obtained from use of fertilizers at TrouD, Nacog- ' doches, Angleton, College Station, Beeville, Temple, and Denton, Texas I I I \. I V‘ VI V I I xi Nacog- Anglé- College Bee- Fertilizer I '1‘roup I doches I ton I Station ville I Temple I Denton used 1927- 1927- 1930- 1927- I 1927- I 1928- I 1928- 1930 1931 1931 1931 1931 1931 I 1931 l I I I I I I $ $ I $ $ I $- I $ I $ s-12-s (s00 lbs.) _______ ..I' | —5.e7**| 5.61 I —9.6s |'—16.90 I-15.4s 1—15.93 Nitrogen varied : I I I I 0-12-4 —2.7 “L65 I 5.52 4,47 —2.92 I 0.22 I —1.33 4-12-4 . 2 4.06 | 5.58 2,11 —4.71 —2.13 -—2.39 4*-12-4 2.47 5.08 —0.12 -—3.37 ——3.95 —2.77 6-12-4 3.51 5.49 0.69 —7.07 —0.42 —3.63 8-12-4 1.66 3.38 6.01 —_3f'30“ »—5.75 —2.21 -4.10 Phosphoric acid '—__' ""’“” “M” varied: 0-4-0 4.95 0-8-0 4.21 4-0-4 ~—3.23 —0.08 —1.34 -—1.98 -—-1.13 —1.03 4-6-4 5,27 5.65 a-LBL —1.26 -—0.57 »—1.56 4-8-4 .01 6.06 $55,, —2.85 —2.22 0.86 4-12-4 4. ' 5.58 2.74 —4.71 -—2.13 —2.39 4-16-4 5.14 Potash varied 4-12-0 4.05 4.98 —2.58 —3.39 —1.67 -—3.57 4-12-2 .441- 0.Iq_,_ —2.72 —2.31 -4.01 4-12-4 . 4.06 5.58 . ——4.71 ~2.13 —2.39 4-12-6 ...................... .. 3.07 Rates of 4-12-4: 200 lbs ..................... .. 2.48 6.72 5.32 2.20 —2.01 —1.72' 0.43 400 lbs._._ 2.92 4.06 5.58 2.74 —4.71 ~2.13 —2.39 600 1bs.... 2.61 2.92 4.99 —1.21 —7.78 —4.93 —2.62 800 lbs._._ __ . -1.09 —1.00 5.70 ~2.27 ——9.61 —8.86 —9.15 1000 lbs ................... .. 5.11 Manure: 8 tons .................... .. **17.08 , 8.27 T2.80 5.91 12 tons .................... .., **22.63 11.36 15.83 5.89 12 tons, 400 lbs”. I superphosphate **19.24 11.08 1‘—1.67 0.65 At 800 lbs: ______________ _. 4-12-4 5.70 6-12 4 5.35 8-12 6.39 10-12 5.99 8-12 6.39 8-12 6.24 8-12 5.67 *One-third of nitrogen in cottonseed meal; two-thirds in sulphate of ammonia. “Average for 1927, 1928, and 1929. "IAverage for 1930 and 1931. and the cost of the fertilizer are known, the reader can calculate for himself the profits or losses obtained from the use of fertilizers under his particular conditions. At Trou ‘the 4-6-4 and 4-8-4 fertilizers were the most profitable treat- ments used, resulting in average profits of $5.40 and $4.49 per acre, respec- tively, for the four years, 1927 to 1930 (Table 16). Those fertilizers that FERTILIZER EXPERIMENTS WITH COTTON 29 did not contain all three elements——nitrogen, phosphoric acid, and potash— were used at a loss. The 0-12-4 fertilizer resulted in a loss of $2.77 per acre; the 4-0-4, a loss of $2.35; and the 4-12-0, a loss of $0.22. The use of 200 pounds per acre of a 4-12-4 fertilizer made the largest average profit, $6.72 per acre, at Nacogdoches. Manure on the average increased the value of the crop about two dollars per acre for each ton of manure used. At Angleton, superphosphate at the rate of 100 pounds per acre (0-4-0 analysis) returned an average profit of $4.95 per acre and the largest profit per dollar invested in fertilizer. Probably the use of 100 pounds of super- phosphate per acre or moderate applications of 4-8-0 fertilizer, 200 to 600 pounds per acre, will be the most profitable fertilizer practice for cotton on the Lake Charles soils. The 0-12-4 and 4-12-4 fertilizers were the most profitable treatments used at College Station, and returned average profits of $4.47 and $2.74 per acre, respectively, for the five years of the experiment. On the aver- age, manure was worth about a dollar per ton. In general, fertilizers have been unprofitable on the Goliad soil at Bee- ville, on the Houston soil at Temple, and on the San Saba soil at Denton. DISCUSSION OF RESULTS The results of the fertilizer work with cotton have been discussed sepa- rately for each section. Now, in order to get a better idea of the results of all the work, the average yields of cotton at each station are brought together in Table 17. The results of these fertilizer experiments show that the sandy soils in the eastern part of the State are deficient in nitrogen and phosphoric acid and to a lesser extent in potash, that the Lake Charles soils in the Gulf Coast Prairie are markedly deficient in phosphoric acid, and that the soils in the Blackland Prairie do not, as a rule, respond readily or profitably to applications of fertilizers. It will be noted from Table l7 that the sandy soils at Nacogdoches and Troup need a complete fertilizer for best results. The use of a 4-8-4 or 4-6-4 fertilizer at the rate of 200 to 400 pounds per acre is suggested for cotton on these soils. The use of manure at the rates of 8 and 12 tons per acre has been worth about two dollars per ton a year at Nacogdoches. The dark-colored prairie soils of the Lake Charles series in the humid part of the Gulf Coast Prairie are deficient in phosphoric acid. The use of 100 pounds of superphosphate or 200 to 600 pounds per acre of a 4-8-0 fertilizer or a fertilizer furnishing similar amounts and proportions of nitrogen and phosphoric acid should give good results when applied to cot- ton on these soils. The Lufkin fine sandy loam at College Station appears to be more defi- cient in phosphoric acid and potash than in nitrogen. The application of the 0-12-4 fertilizer made the largest average profit per acre”, which, how- ever, was due largely to the good results obtained in 1929. 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" poo woo o wow lwo woo wo wfi G mop ||mw :3 wo woo wo p|o|p ; poo mop op wow aw wfi wwq mmw ow wpw mo mwo wm wwa mm p-wp poo moo oo mom mm woo wmo mmo mo wmo Q mww mp wpw po poo mpw om wop qp poo wwo N3 2 wwo w NE po wmp mo poo mmp wp moo wo woo wwo mpo wo wow .|mw mwp m4 woo ww poo mww pw wop 4p .... z m3 fi mmo w mmw wp wwo wm poo mpw ow wop i poo wwo m3 2 wwo m Nfi po wmp mo moo mmo wo :3 2 m3 3 3w pm www o woo wm wmw mo poo mpw om wop 3 poo wwo N3 3 wwo w Emma po wmp mo ooo moo 2 mww ow $2 :3 mom om wpw wo NE po wpq om woo mom S mwm om p2 mwo wow i. wpw S mmp 3 o3 mm *O:m|$;§w ow sowuomm: wswvurmo o: nowwosmmmo 3mm; 25 §o-§§m o: mcwurmwm ow. W550i». FERTILIZER EXPERIMENTS WITH COTTON 31 4-12-4 fertilizer or an analysis supplying equivalent amounts and propor- tions of plant food is suggested for cotton on the Lufkin soils. Manure when used at the rates of 8 and 12 tons per acre increased the value of the cot- ton crop about one dollar per acre for each ton of manure used. The dark-colored soils of the Goliad series at Beeville have responded to some extent to applications of nitrogen, of phosphoric acid, and of potash. As a rule, however, none of the fertilizers used was profitable. Somewhat similar results have been obtained on the Houston black clay at Temple and on the San Saba clay at Denton. SUMMARY The results obtained in the experiments with fertilizers on cotton at the several substations lead to the following conclusions: The sandy soils in the eastern part of the State are deficient in nitro- gen, phosphoric acid, and potash. The application of 200 to 400 pounds per acre of a 4-6-4 or 4-8-4 fertilizer or a fertilizer supplying similar ratios and amounts of plant food is recommended for cotton on these soils. The Lake Charles soils in the Gulf Coast Prairie are first in need of phosphate. The use of 100 pounds of superphosphate or 200 to 600 pounds of a 4-8-0 fertilizer per acre or a fertilizer with equivalent amounts and proportions of plant food is suggested for cotton on these soils. The Lukfin fine sandy loam apparently needs phosphoric acid and potash before it does nitrogen. The 4-12-4 and 0-12-4 fertilizers gave better re- sults on this soil than the other fertilizers used. Although fertilizers gave some response on the Goliad fine sandy clay loam at Beeville, on the Houston clay and Houston black clay at Temple, and on the San Saba clay at Denton, in general the use of fertilizers was not profitable on these soils.