G The Bulletin. 



(from N^PK to N3PK) has resulted in returns on an average equiva- 

 lent to 69 cents for each pound of nitrogen added between 5 and 30 

 pounds per acre. The use of 30 pounds of nitrogen, with the exception of 

 the two and one-half times normal fertilizer application, was the most 

 profitable one tried. Five pounds of nitrogen would be supplied by 81 

 pounds of 7^ per cent cottonseed meal, by 40 pounds of 15 per cent 

 dried blood or by 34 pounds of 18 per cent nitrate of soda. 



5. The amount of phosphoric acid in the normal fertilizer (400 

 pounds per acre) was 7 per cent which is equivalent to 28 pounds per 

 acre. This quantity was varied so as to apply 14, 28, 56 and 84 pounds 

 respectively of phosphoric acid per acre, with normal amounts of nitro- 

 gen and potash. These amounts of phosphoric acid would be supplied 

 by 100, 200, 400 and 600 pounds respectively of 14 per cent acid phos- 

 phate. The greatest net returns over cost of fertilizer per acre was 

 secured in the study of the most profitable quantity of phosphoric acid 

 to use on cotton, by the use of 28 pounds per acre. 



6. The amount of potash in the normal fertilizer (400 pounds per 

 acre) was 2^ per cent, equivalent to 10 pounds per acre. Varying 

 this amount so as to apply 5, 10, 20 and 30 pounds per acre respectively, 

 the results indicate (with one apparently abnormal exception) that the 

 largest profit over cost of fertilizer from different quantities of potash 

 was obtained from the use of about 20 pounds of potash with normal 

 amounts of nitrogen and phosphoric acid. To supply 20 pounds per 

 acre of potash will require an application of 167 pounds of 12 per cent 

 kainit, 100 pounds of 20 per cent manure salt, or 40 pounds of 50 per 

 cent muriate or sulphate of potash. 



7. Varying the amounts of the normal fertilizer applications from 

 200 to 1,000 pounds per acre gave progressively increased yields and 

 profits as the quantity of fertilizer was made larger, the results being 

 quite uniform on an average in this regard. The averages, after de- 

 ducting for cost of fertilizer showed the following net profits: 



200 pounds of fertilizer per acre gave a profit of $ 5.95. 

 400 pounds of fertilizer per acre gave a profit of 11.45. 

 600 pounds of fertilizer per acre gave a profit of 23.70. 

 800 pounds of fertilizer per acre gave a profit of 31.63. 

 1,000 pounds of fertilizer per acre gave a profit of 34.47. 



Putting this in a slightly different way, on an average the first 200 

 pounds of fertilizer yielded a net profit (after deducting for the cost of 

 ifertilizer) of $2.98 for each 100 pounds of fertilizer; the application of 

 400 pounds yielded $2.86 per 100 pounds; 600 pounds yielded $3.95 

 per 100 pounds; 800 pounds yielded $3.95 per 100 pounds; and 1,000 

 pounds yielded $3.45 profit per 100 pounds of fertilizer. 



8. Comparisons of dried blood and nitrate of soda as sources of 

 nitrogen showed no great advantage one over the other in the production 

 of cotton on this type of soil. In the tests nitrate of soda was applied 

 one-half at planting and one-half about July 1, on one plat; one-half 

 was applied about July 1, the other half of the nitrogen coming from 

 dried blood, which was applied before planting on another plat, and 



