1 4 t L 2' - LI ) '~K Coi' CflT 3 FF BULLETIN No. 184 MAY, 1915 ALABAMA Agricultural Experiment Station OF THE Alabama Polytechnic Institute AUBURN Local Feritlizer Experiments With Sweet Potatoes BY J. F. DUGGAR Director and J. T. WILLIAMSON Field Agent in Agriculture Montgomery, Ala. The Paragon Press. 1915 COMMITTEE OF TRUSTEES ON EXPERIMENT STATION. H ON. R. F. KOLB .................................................................... . .............. M ontgom ery H oN. A. W. BELL ..................................... ................ H ON . J. A . R OGERS .............................................. ...Anniston ............................. G ainesville STATION STAFF. C. C. THACH, President of the College. J. F. DUGGAR, Director of Experiment Station and Extension. AGRICULTURE: J. F. Duggar, Agriculturist. E. F. Cauthen, Associate. M. J. Funchess, Associate. J. T. Williamson, Field Agent. D. J. Burleson, Assistant. O. H. Sellers, Assistant. H. B. Tisdale, Assistant. VETERINARY I. B. Kerlin, Assistant. * Nellie M. Tappan, Home Economics. ** BOTANY: J. S. Caldwell, Botanist. A. B. Massey, Assistant. PLANT PATHOLOGY: SCIENCE: F. A. Wolf, Pathologist. HORTICULTURE: C. A. Cary, Veterinarian. H. C. Wilson, Hog Cholera Expert.* L. F. Pritchett, Assistant. CHEMISTRY: J. T. Anderson. Chemist, Soils and Crops. C. L. Hare, Physiological Chemist. S. Adler, Assistant. JUNIOR AND HOME ECONOMICS EXTENSION: Ernest Walker, Horticulturist. J. C. C. Price, Associate. G. V. Stelzenmuller, Field Agent. ENTOMOLOGY: W. E. Hinds. Entomologist. F. L. Thomas, Assistant. E. A. Vaughan, Field Asst. ANIMAL INDUSTRY: L. N. Duncan, Superintend- ent. * Miss Madge J. Reese, Assistant. * J. C. Ford, Assistant. * S. Templeton, Animal Husbandman. E. S. Girton, Assistant. N. A. Negley, Assistant.* E. Gibbens, Assistant. G. *In cooperation with United States Department of Agriculture. **In cooperation with Alabama Girl's Technical Institute. LOCAL FERTILIZER EXPERIMENTS WITH SWEET POTATOES. By J. F. DUGGAR, Director. and J. T. WILLIAMSON, Field Agent in Agriculture. SUMMARY. Of nine conclusive experiments made on various soils (1) the largest increase in yield was afforded by phosphoric acid in five experiments, and by nitrogen in two experiments. In none was kainit more effective than acid phosphate. (2) In five experiments cotton seed meal was more effective than an equal weight of kainit, and in only one was kainit notably more effective than meal. (3) Taken as a whole these experiments seem to indicate that the popular idea that potash is the most important constituent in a fertilizer for sweet potatoes is incorrect, at least as to practically all of the soils here represented. On the other hand, these tests show that phosphate and nitrogen were much more important than potash. (4) These experiments also seem to discredit the notion that the use of a fertilizer containing nitrogen causes the sweet potato plant to run to vines to an injurious extent. In our experience this danger does not occur where reasonable amounts of nitrogen are used in combination with acid phosphate. (5) The following general fertilizer formulas are suggested where the conditions justify rather high fertilization: For sweet potatoes growing on fresh land, or on sandy (a) land in rather high state of fertility, a fertilizer consisting of 200 pounds cotton seed meal per acre, 400 pounds acid phosphate and 200 pounds of kainit. This would analyze about 1.6 per cent nitrogen, 8.7 per cent available phosphoric acid, and 8.5 per cent potash. (b) For sandy land long in cultivation, and not in a high state of fertility it would seem advisable to increase the proportion of nitrogen, using for example, a formula somewhat like the following: 300 pounds cotton seed meal per acre, 400 pounds acid phosphate, and 200 pounds kainit. This would analyze about 2.2 per cent nitrogen, (equivalent to 2.7 per cent ammonia,) 8 per cent available phosphoric acid, and 3.3 per cent potash. 20 LOCATION OF EXPERIMENTS. These experiments were made by farmers in Mobile, Baldwin, Cullman and Sumter Counties. The Exepriment Station furnished the plans, weighed and sacked the fertilizer, measured the plots, and sent a representative to inspect the plots as often as practicable. The following list gives the name and address of each experimenter who carried the experiment to a satisfactory conclusion. County P. O. Name B aldwin.......................... Foley ............ ey ............. ..... A. Friskhorn Baldwin............. ............... Robertsdale ........................ A. N. Hayselden Cullman...................... .Cullman...........Cullman. I. O. O. F. Home ........................ M obile.................................. Irvington .......................... Irvington Land Co. Mobile ....................... ...Mob.............Mobile Mobile Farm Land Co. ........... Sum ter............................ . ub ............................................... W . H . Stephens THE FERTILIZERs USED. The following prices are used, as representing a rather high average cash price in local markets during the last few years 1911, 1912, 1913 and 1914: Per Ton Acid Phosphate (16 per cent available)...........................$14.00 Cotton Seed Meal ............................... $30.00 Kainit .... .................................................................................................. $ 14 .00 Nitrate of Soda ($50 in 1911 and 1912) ................................... $60.00 Prices naturally vary in different localities. Any one can substitute the cost of fertilizers in his locality for the prices given above. In each experiment, except that conducted by A. W. Hayselden, three plots were left unfertilized, these being Plots 3, 7 and 11. When these yields differed widely the experiment was classed as inconclusive. The increase on plots 4 to 6 is calculated on the assumption that the gradation in fertility is uniform from plots 3 to 7; likewise the increase is calculated .for plots 8 to 10 inclusive.* PRICES ASSUMED FOR SWEET POTATOES. The price assumed per bushel of sweet potatoes is 60 cents in each of the four years. *For the standard method employed in this bulletin for calculating the increased yield, see Alabama Station Bulletin 160 or 162. 21 POUNDS PER ACRE OF FERTILIZERS; NITROGEN, PHOSPHORIC ACID AND POTASH USED, AND A COMPOSITION OF EACH MIXTURE. FERTILIZERS CONCOST CONTAINS MIXTE OF FERTILIZERS 1913-14 KIND Z - OF FERTILIZER - -o o .,) -, *0 0 On Lbs. Lbs 200 Cotton seed meal---------13.581 In 100 lbs. c. s. meal*.... 6.79 2 240 Acid In Lbs. 5.76! 2.88 3.40.... Lbs. 3.54 1.77 - $30.00!$6.00 phosphate ..................-- 100 lbs. acid phos... ......... 16.00 44.16 4 5 200 Kainit--------------------------24.60 In 100 lbs. kainit-...-....---------12.30 200 Cotton 5 1400 3.36 14.00 2.80 9.36 seed meal.........13.58 3.54 6 811 9 240 Acid phosphate. .... c21.27 ............3.09 10.04 0.80 In 100 lbs. above mixt.. 5.76 28.14 200 Cotton seed meal---..-. 13.58 200 Kainit ................. ...........3.39 1.44 7.03 In 100 lbs. above mixt.. 2401IAcid phosphate-.... 2001 Kainit--------------------------In 100 lbs. above mixt.--------8.73 5.59 22.00 13.99 8.80 6.16 240 Cotton seed meal -1--200 Acid phosphate-----------200 Kainit -------------------- J In 100 lbs. above mixt-. 1 (1 200 Cotton seed meal240 Acid phosphate-----------... 10 L 100 Kainit --------------- ----- J In 100 lbs. above mixt I f 13.58 44.16 2.12 6.90 28.141 4.40 15.841 2.93J 12.30 2.80 19.00 12.16 13.58j 44.16 2.59 8.18 16.00 3.18! 8.73 20.13 10.76 12f { 240 Acid phosphate----------1 100 Kainit----------14.00 100 Nitrate of soda ------- In 100 lbs. above mixt-. j }(24.45 ** ** 10.76 _______ *Average of many analyses. **Counting all the phosphoric acid in cotton seed meal as available. ***Only $22.17 in 1911 and 1912. ****Only $4.88 in 1911 and 1912. Those farmers who are more accustomed to the word ammonia than to the term nitrogen, can change the figures for nitrogen into ammonia equivalents by multiplying by 1 3-14. 22 .BALDWIN COUNTY, NEAR FOLEY, A. FRISKHORN-1911. Sandy Soil, Not Long in Cultivation. The largest average increase, 57 bushels per acre, was due Lo 240 pounds of acid phosphate. The second largest increase, 30 bushels per acre, was attributable to 200 pounds of cotton seed meal. Kainit was not only useless, but apparently somewhat harmful when used at the rate of 200 pounds per acre. At the rate of 100 pounds per acre it slightly increased the yield. By noting the figures in the table on page 23 the reader may note the yield afforded by each fertilizer formula, and its increase in potatoes and in profit over the unfertilized plots, calculated as before mentioned. Then by carefully reading the data as dissected or analyzed on page 24 one may note the extent to which any increase in any particular fertilizer formula was apparently due to each separate fertilizing material, namely, cotton seed meal, acid phosphate, or potash. 23 ' FERTILIZER TOES IN EXPERIMENTS WITH SWEET POTA1911. BALDWIN AND MOBILE COUNTIES IN FOLEY-1911 13BILE-1911 MO ~® O . 4) KIND OF _ I. I r, il 8 V FERTILIZER- C N V tJ a'Ca .- CaV V. - 449.8 O N _ 1 2 3 4 5 ____ Lbs. 200 C. S. Meal ................. 240 Acid fertilizer .............. 200 Kainit...... ................... 200 C. S. Meal...........------200 Kainit...............5-------- No phosphate........----- Bus. 82.2 96.0 38.5 20.5 131.0 38.5 48.3 81.9 115.6 145.8 54.21 82.6 11~ _ ___ Bus. 43.7 57.5 -20.5 87.6 -7.5 32.1 64.3 93.11 .----. 28.41 cC tiZ $23.22 32.82 .. -13.70 Bus. IBus. 74.7 104.9 24.9 . 23.9 137.1 80.0 3$20.88 46.32 -3.6 3-3.56 47.88 107.0 58.2 .-"--- 59.52 30.52 6 200 C. S. Meal...........------200 Kainit...............--------No fertilizer..........-------phosphate.......5---.... ................. j 2001 C. S. Meal...........------240 Acid -8.90 90.9 -----..35.3 16.18 32.50 2001 Kainit 116.3 156.6 81.9 a46.06 2401 Acid phosphate ....... 2001 Kainit.........-------...----200 (C. 123.2 61.0 71.6 . 67.84 37.58, 10{ 11 12 2401 Acid 24O1lAcid INo S. Meal...........------- phosphate.------fertilizer...........------- 50.48 92.61 104.1 31.6 l00 Kainit...............J-------phosphate.------- 1 100 INitrate of __^I--~. I 100 Kainit............... soda.------- 12.161 31.72' I ._^.I 24 Increase of sweet potatoes per acre when cotton seed meal was added: To unfertilized plot ...................................................... 48.7 bus. To acid phosphate plot ......................... .......... 0.1 bus To kainit plot ...................................... ...................................... 18.0 bus. To acid phosphate and kainit plot ............................ 32.2 bus. Average increase with cotton seed meal ..................... 29.8 bus. Increase of sweet potatoes per acre when acid phosphate was added: To unfertilized plot .............................. 57.5 bus. To cotton seed meal plot ............... ......... 48.9 bus. To kainit plot ............................................ 52.6 bus. To cotton seed meal and kainit plot .. ............ 71.8 bus. Average increase with acid phosphate.............................56.5 bus. Increase of sweet potatoes per acre when kainit was added. To unfertilized plot ...................................... . ..... ............... 0.5 bus. To cotton seed meal plot ....................... 51.2 bus. To acid phosphate plot ...........................................- 45.4 bus. To cotton seed meal and acid phosphate plot..................-2 bus. Average increase with kainit ................................ 85.1 bus. MOBILE COUNTY, NEAR MOBILE. MOBILE FARMVI LAND Co.-1911. Sandy Soil, Recently Cleared. For yields and increase and profit due to each fertilizer formula see the table on page 23. The most effective fertilizer constituent was acid phosphate. The average increase due to 240 pounds of acid phosphate in four different combinations was 72 bushels per acre. The largest increase, 107 bushels per acre, was obtained on Plot 5, fertilized with cotton seed meal and acid phosphate. The fertilizer, constituent second in importance was cotton seed meal, which afforded an average increase of 45 bushels per acre. On the other hand, kainit gave a very slight increase. The following analysis shows the apparent effect of each fertilizer constituent, considered separately: Increase of sweet potatoes per acre when cotton seed meal was added: ...................... 49.8 bus. To unfertilized plot .......................... To acid phosphate plot ..................................... ...................... 27.0 bus. 61.8 bus. To kainit plot ............................................. 41.3 bus. To acid phosphate and kainit plot ............................ Average increase with cotton seed meal ........................ 45.0 bus. 25 Increase of sweet potatoes per acre when acid phosphate was added: To unfertilized plot ..................................................... 80.0 bus. To cotton seed meal plot ........................... .. ............ 57.2 bus. To kainit plot.... ........... ........................ ................................ 85.5 bus. To cotton seed meal and kainit plot ................................. 65.0 bus. Average increase with acid phosphate ........................... 71.9 bus. Increase of sweet potatoes per acre when kainit, was added: To unfertilized plot ................................... ......... 3.6 bus. To cotton seed meal plot.......................... ............. 8.4 bus. To acid phosphate plot ................................... ......... 1.9 bus. To cotton seed meal and acid phosphate plot ............. 16.2 bus. Average increase with kainit .................... ........... 5.7 bus. BALDWIN COUNTY, 1/4 MILE EAST OF ROBERTSDALE H. W. HAYSELDEN-1912. Gray sandy loam with yellow subsoil; recently cleared. It should be noted that in all experiments in this bulletin hereafter described, the rate per acre at which each fertilizer is used is double the rate employed in all the experiments made in 1911, and already detailed. This experiment was made on fresh land. The largest average increase, 90 bushels per acre, resulted from the use of 480 pounds of acid phosphate. The next largest increase, 82 bushels per acre, was due to cotton seed meal. Kainit ranked third in importance, but afforded a larger increase than did kainit in any other experiment reported in 1911 or 1912-namely, in the complete fertilizer containing 400 pounds of kainit, an increase of 40 bushels; and in the complete fertilizer containing 200 pounds of kainit, an increase of 24 bushels per acre attributable to kainit. In this experiment the complete fertilizer afforded the largest increase, namely 240 bushels per acre. Note that the unfertilized plot was exceedingly unproductive, yielding only 32 bushels per acre. ROBERTSDALE-1912. dN C) MOBILE-1912. O KIND OF W W 03 z 0) 0 3 FERTILIZER. 1 0 30 0C OC CO 00u O y 63 0.2 Lbs. F'1 128. 1 2 480I Acid phosphate --------INo fertilizer ----------400,1K ainit ------- ----- --------- ------400 C. S. M eal 5% 11 280I Acid phosphate -----------------400 C. S. M eal 400 K ainit -------W 'y 4001C. S. Meal ------------- 232.0 Bus. 96.0 96.0 96.0 200.0 $51.60 54.24 54.80 3. 110.64 77'.60 89.84 131.84 123.64 24.0 141.7 I II I 41.4 60.0 - .0 139.4 -5.5 10 161.1 18.3 14.0 120.0 31.9 162.4 154.0 158.4 91.284 80.28 ----- =- No fertilizer -----------85i 480 Acid 286.0 144.0 160.0 200 Kainit 400 K ainit phosphate ----- --------------- ------- 5 j 400 C. S. Meal ------------480 Acid phosphate.------W -r 4001 C. 11 12 I- --------- J------ 240.0 224.0 S. Meal ------------- 1 phosphate---------------------------- 480 Acid NW 2001IKainit j No fertilizer --------------I 84.28 12001INitrate J . I 4SOIAcid phosphate --------- 1 2001 Kainit -------------------of soda ------- 117.7, I 59.86 27 The following analysis attempts to show the increase in yield per acre apparently due to each separate fertilizer constituent when each was used in various combinations: Increase of sweet potatoes per acre when cotton seed meal was added: To unfertilized plot .................................................... ................. 96.0 bus. ... .......... 104.0 bus. To acid phosphate plot .................... ..................... 48.0 bus. T o kainit plot .................................. To acid phosphate and kainit plot ................................. 80.0 bus. Average increase with cotton seed meal ..................... 82.0 bus. Increase of sweet potatoes per acre when acid phosphate was added: ................ 96.0 bus. To unfertilized plot ..................... .......... 104.0 bus. To cotton seed meal plot ........................ 64.0 bus. .......................... ........ ................. . To kainit plot To cotton seed meal and kainit plot ................................. 96.0 bus. Average increase with acid phosphate ........................... 90.0 bus. Increase of sweet potatoes per acre when kainit was added: To unfertilized plot ................................................... 96.0 bus. 48.0 bus. To cotton seed meal plot ............................................. To acid phosphate plot ............................................................... 64.0 bus. To cotton seed meal and acid phosphate plot ................. 40.0 bus. 62.0 bus. .............. Average increase with kainit ...................... MOBILE COUNTY, NEAR MOBILE MOBILE FARM LAND Co.-1912. Gray sandy loam with stiffer yellowish subsoil; new ground. For yields see table on page 26. This is new or second-year land, following a poor crop of cowpeas. The largest average increase, 127 bushels per acre, again resulted from the use of acid phosphate, this time applied at the rate of 480 pounds per acre. This large increase was obtained by taking the average increase attributable to acid phosphate applied in four different combinations,-a method which is used for getting the average increase of all fertilizers. The average increase due to 400 pounds of cotton seed meal was only 12.8 bushels, probably because of the newness of the land and the growing of a preceding crop of cowpeas. Kainit afforded only a slight increase, namely, an average of 10.4 bushels. However, kainit gave a better account of itself in the complete fertilizer, affording on Plot 9, an increase of 34 bushels per acre attributable to 400 pounds of kainit, and on Plot 10 an increase of 28.4 bushels attributable to 200 pounds of kainit. 28 Increase of sweet potatoes per acre when cotton seed meal was added: To unfertilized plot .............................................. 414 bus. To acid phosphate plot ............................... .... .....- 19.4 bus. T o kainit plot .................................. ............................ 7.4 bus. To acid phosphate and kainiit plot ................................. -8.4 bus. Average increase with cotton seed meal ..................... 12.8 bus. Increase of sweet potatoes per acre when acid phosphate was added: To unfertilized plot .................................................. 139.4 bus. To cotton seed meal plot ............................. .... ................. 78.6 bus. To kainit plot ............................................ ...................... 167.9 bus. To cotton seed meal and kainit plot ............................ 122.1 bus. Average increase with acid phosphate...................................127.1 bus. Increase of sweet potatoes per acre when kainit was added: To unfertilized plot ......................................... 5.5 bus. To cotton seed meal plot ......................... .........9.5 bus. To acid phosphate plot ......................................... 23.-0 bus. To cotton seed meal and acid phosphate plot.................. 4.0 bus. Average increase with kainit ................... .......... 10.5 bus. MOBILE COUNTY, 14~ MILE NORTH OF IRVINGTON. IRVINGTON LAND COMPANY-1912. Dark gray sandy loam, with stiffer reddish subsoil. For yields, see table on page 29. This field had been in cultivation about 14 years. Here we find that acid phosphate and kainit were equally effective, each affording an average increase, for four different conditions, of 34 bushels per acre. In the complete fertilizer on Plot 9, both kainit and acid phosphate were even more effective, the increase attributable to each one here being 89 bushels per acre. While this land has been in cultivation for 14 years, it was in fairly good condition as shown by a yield of more than 100 bushels per acre on one of the unfertilized plots. Under these conditions cotton seed meal was only effective in the complete fertilizer, in which, on Plot 9, there was an increase of 34 bushels per acre attributable to 400 pounds of cotton seed meal. IRVINGTON LAND CO.. MOBILE. O IRVINGTON LAND CO., SUMTER. 0 w _o KIND OF w . a O . s 2( N N V _.- Z w o FERTILIZER. -n4- 4-' Bus. -33.1 10.6 11.0 -4 H -ri 1 2 3 Lbs. Bus. 400 C. S. Meal -------------------- 80.6 480 Acid phosphate-------------- 124.3 4( 55 No fertilizer -------------- 1137 400 Kainit ---------------------120.9 S. Meal-.......--...---------- 4O01C. ---- -$25.86 3.00 3.80 Bus.158.9 201.7 191.4 Bus. -32.5 10.3 23.5 - -$25.50 2.82 11.30 206.0 65 7 1o w 851 9 w w 4 480 Acid phosphate-90.6 400 C. S. Meal ----------400 (Kainit------------------------No fertilizer -----------------48OIAcid phosphate ------------- -15.4 86.9 98.3 132.6 -=15.4 34.2 67.8 -18.60 -18.04 14.36 28.52 214.3 214.3 155.7 157.1 162.9 40.7 49.7 15.06 21.02 400 Kainit ---------------------400 C. S. Meal ---------------------- 1 480 Acid phosphate ------------4001IKainit-------------------J 4001 C. S. Meal ----------- 166.3 173.7 101 11 12j 175.2 34.36 480 Acid phosphate------------ --------------- J L12001 Kainit -----( No fertilizer------------------- 4901JAcid 2001 98.6 26.0 4.84 phosphate----------1 of soda--J---------L w w 200jNitrate Kainit----------124.6 30 Increase of sweet potatoes per acre when cotton seed meal was added: ..........- 33.1 bus. To unfertilized plot ........................................ .....- 26.0 bus. To acid phosphate plot ..................................... bus. To kainit plot..................................26.4 To acid phosphate and kainit plot....... -13.0 bus. Average increase with cotton seed meal.......... Increase of sweet potatoes per acre when acid phosphate was added: ............. 10.6 bus. To unfertilized plot ....................................... ........... 17.7 bus. To cotton seed meal plot ............................... .................. 23.2 bus. ................ To kainit plot ......... 83.2 bus. To cotton seed meal and kainit plot ....... .............. 33.7 bus. Average increase with acid phosphate Increase of sweet potatoes per acre when kainit was ............. 11.0 bus. To unfertilized plot ........................................ ....... 17.7 bus. To cotton seed meal plot .............................. ....... 23.6 bus. To acid phosphate plot ..................................... 83.2 bus. To cotton seed meal and acid phosphate plot........ ....... 33.8 bus. Average increase with kainit ........................ added: SUMTER COUNTY, 1 MILE NORTH OF CUBA. W. H. STEPHENS. Gray sandy soil, with yellowish sandy subsoil. This upland field had been in cultivation for many years. The three preceding crops were cotton. KIND OF o S FERTILIZER. JLbs.f 1 200 C. S. Meal No ..................... Bus. 2 3 240 Acid phosphate.............. 201.7 ( 4 158.91 Bus. 32.51$ 10.3 25.50 2.82 11.30 5f . 7 240 Acid phosphate ............. 6 200 C. S. Meal...........-------- 2001 Kainit Meal............-------200 C. S. .... fertilizer..............------191.41............------- ...................... 206.01 23.5 214.31( 40.7 15.06 ( ................. 2001IKainit ....... No fertilizer S. Meal .................. 8 9 240lAcid phosphate S 2001 Kainit....... ................. 1 49.7 21.02 214.31 -----............ 155.71 1 II2001fC. ....... 1 .157.11............------- 240 Acid phosphate ........ 200 K ainit -J-------_------------- 162.9....... The following analysis is made in order to indicate the apparent increase in yield attributable to fertilizer constituent, considered separately: Increase of sweet potatoes per acre when cotton seed meal was added: To unfertilized plot .......................................... 2.5 bus. To acid phosphate plot ................ .......... 30.4 bus. To kainit plot ............... ......... ........... ............. 26.2 bus. Average increase with cotton seed meal ............. 8.0 bus. Increase of sweet potatoes per acre when acid phosphate was added: To unfertilized plot ...................................... .. .............. 10. 3 bus To cotton seed meal plot................................... .............. 73.2 bus. Average increase with acid phosphate ..................... 41.8 bus. Increase of sweet potatoes per acre when kainit was added: To unfertilized plot ........................... ....................... 23.5 bus. To cotton seed meal plot ................................. . ... ............ 82.2 bus. Average increase with kainit ..................... .......... 52.8 bus. -3..... CULLMAN COUNTY, 1-1/2 MILES NORTH OF CULLMAN I. O. O. F. HOME (ED. B. MILLER, SUPT.) A gray sandy loam, with stiffer yellowish subsoil. The soil on which the tests were made in each of three years is apparently that designated by the Bureau of Soils as "DeKalb Fine Sandy Loam." In 1912, this upland field had been in cultivation for about 5 years. A preceding crop of peas and beets in 1911, well fertilized, had left the land in good condition, as shown by a yield of above 150 bushels of sweet potatoes per acre without any fertilizer whatsoever. Acid phosphate was this year the most effective fertilizer, affording an average increase of 47.8 bushels per acre. Under these conditions cotton seed meal was but slightly effective; the average increase was only 5.5 bushels per acre, which is explained by the fairly fertile condition of the land. Kainit was of but little value. The largest increase, 92.9 bushels per acre, was obtained on Plot 10, fertilized per acre as follows: 400 pounds cotton seed meal, 480 pounds acid phosphate, 200 pounds kainit. FERTILIZER EXPERIMENT WITH SWEET POTATOES IN CULLMAN COUNTY. CULLMAN-1912. j S CULLMAN-1913. CULLMAN-1914. AVERAG KIND OF o aa a B - FERTILIZER. r 1 2 3 4 51 6 j Bus. Lbs.T 400 C. S. Meal ------------------- 141.1 480 Acid phosphate ------------- 210.3 No fertilizer------------------ 139.4 185.4 -------------------400 Kainit ----..... 400 C. S. Meal. 480 Acid phosphate------------225.4 S 4001IKainit-------------------------- 198.6 I No fertilizer---- ------- 156.6 480IAcid phosphate----400jC. S. Meal - -------------- 1 480' Acid phosphate ----------- 243.7 400 Kainit-----------------------226.6 Bus. 1.7 70.9 41.7 77.4 46.3 61.9 -$4.98 39.18 22.22 Bus. 395.7 354.3 277.1 377.1 440.0 404.9 355.7 445.7 Bus. 118.6 77.2 80.3 123.6 68.8 67.2 $65.16 42.96 45.38 64.80 32.48 34.16 Bus. 401.4 360.0 282.0 384.6 454.3 417.1 353.1 458.3 Bus. 119.4 78.0 84.8 136.7 81.8 83.2 I $65.64 43.44 48.08 72.66 40.28 43.76 Bus.1 79.9 75.4 68.9 112.6 69.0 70.8 $19 418 385 581 305 360 5.2 510 4001C. S. Meal. -------------- I 37.08 18.98 30.98 8 9 10 1I ---ff 92.9 4.9 48OIAcid phosphate-----------} 273.7 L1 200 Kainit----- ------------------ 18.I 11 Nofertilizer ------------- ,189446.940. 48 4OAcid phosphate -------- 1 61.7 26.26 12 400 Kainit ---------------------- ~ 250.6 J.L......___________.) 200jNitrate of soda 4001 Kainit 4001 70.9 30.38 518.5 521 117.2 103.0 58.16 51.04 545.7 532.0 40. 608.6 148.7 113.0 77.06 57.04 112.3 103.0 ---C. S. Meal- ----------------- J 574.3 127.4 65.68 167.7 89.86 118.9 600 33 Increase in bushels of Sweet Potatoes per acre due to 400 pounds per acre of Cotton Seed Meal, or 480 pounds Acid Phosphate, or 400 pounds Kainit: ~LII~I~CI~C 111 UU~IICI~ V1 ~VVCCL I U AVERAGE 1912 1913 1914 INCREASE 3 YRS. Increase of sweet potatoes per acre when cotton seed meal was added; To unfertilized plot .............................. 1.7 To acid phosphate plot. ................... 6.5 To kainit plot ................ ....................... 4.6 To acid phosphate and kainit plot........ 9.0 Average increase with cotton seed meal Increase of sweet potatoes per acre when acid phosphate was added; To unfertilized plot ................................ 70.9 75.-71 To cotton seed meal plot ........................ To kainit plot .. ............................... 20.21 To cotton seed meal and kainit plot ... 24.61 Average increase with acid phosphate 47.8 Increase of sweet potatoes per acre when kainit was added; To unfertilized plot ............................... 41.71 To cotton seed meal plot................. 44.61 To acid phosphate plot ........................... -9.0 To cotton seed meal and acid phosphate plo t.................................................. -6.5 Average increase with kainit ................ 17.7 118.6 46.4 -11.5 50.0 50.9 119.4 58.7 -3.0 65.5! 60.21 78.0 17.3 -1.6 79.9 37.2 -3.3 41.5 38.9 75.4 32.7 1.8 46.6 39.1 68.9 -14.3 -4.6 -0.3 12.4 77.21 5.01 -13.11 48.4 29.4 66.9 40.2 I 80.31 -49.81 -10.0 -6.4 3.5+ 84.8 -37.61 5.2 12.0 16.1 Average increase due to nitrogen, phosphoric acid and potash. Special attention is called to the column of figures on page 33 showing the average increase due to each fertilizer in each of four different combinations. This shows that on the whole nitrogen and phosphoric acid were uniformly profitable and about equally effective. The figures also show that kainit at the rate of 400 pounds per acre was on the whole of little or no advantage in increasing the yield. In all three of the experiments near Cullman, nitrate of soda, applied after the slips were set, was more effective than double its weight of cotton seed meal applied before the slips were set. In 1913. This year the experiment was on the same character of soil, but on a different field. The yields were large on all plots. The largest yield, 574.3 bushels per acre was obtained on plot 12, fertilized as follows per acre: 480 pounds acid phosphate, 400 pounds kainit, 200 pounds nitrate of soda (the latter applied after growth began.) The largest increase due to fertilizer, 127.4 bushels 34 per acre, was obtained on the same plot, as was also the largest net profit from fertilizers, $65.68. This experiment was again on similar soil, but in a different field. Again the largest yield, 608.6 bushels, the largest increase from fertilizers, 167.7 bushels, and the largest profit from fertilizers, $89.86 per acre, were obtained on plot 12, fertilized as mentioned above. Attention, is called to the large yields in all three years, and especially in 1913 and 1914. In both of the years lastmentioned the yields on all three of the plots receiving complete fertilizers (Plots 9, 10, and 12) exceeded 500 bushels per acre. Even on the unfertilized plots the average yield for each of these two years was above 300 bushels per acre. The largest average increase due to fertilizers at Cullman, 118.9 bushels per acre, was obtained on Plot 12. The plot also afforded the largest average profit from fertilizers, namely, $60.00 per acre. This plot was fertilized as follows: 480, pounds acid phosphate per acre, 400 pounds kainit per acre, 200 pounds nitrate of soda per acre (the latter after growth began.) 1080 pounds total per acre. However Plot 12 was very closely followed in increase and profit by Plot 5, which afforded a larger profit than any other plot that received cotton seed meal. In 1914.