28 The Bulletin. 



Effect of Vakying Quantities of Phosphoric Acid. 



The above experiments (in Table III) were planned to show the effect 

 on the yields of seed cotton of varying quantities of phosphoric acid, the 

 nitrogen and potash remaining the same. On one plat one-half the 

 normal quantity of phosphoric acid was applied, or an amount repre- 

 sented by 100 pounds of 14 per cent acid phosphate and equivalent to 

 3% per cent phosphoric acid in the fertilizer mixture. On two plats 

 were applied two and three times the normal quantities of phosphoric 

 acid, represented by 400 and 600 pounds of 14 per cent acid phosphate 

 respectively, or 56 and 84 pounds of phosphoric acid per acre. 



Varying the amounts of phosphoric acid had no very marked effect 

 on the yield of cotton. The application of more than normal — 28 

 pounds per acre — which is equal to an application of 200 pounds of 14 

 per cent acid phosphate failed to increase the yield, and consequently 

 gave less profit. However, when the amount was reduced to one-half 

 normal both yield and profit were less. It is well to remember in this 

 connection that nitrogen and potash alone (see Table I) gave a larger 

 yield and greater profit than did any of the mixtures contaiiiing phos- 

 phoric acid. These results certainly indicate that the application of 

 phosphoric acid in the form of acid phosphate is not accompanied with 

 much profit. 



