68 The Bulletin 



acre, and for tliree years in Field B being 661.6 pounds, or an average 

 annual increase per acre for the eight years on the two fields of 524.6 

 pounds of seed cotton per acre, worth $19.57 above cost of fertilizer. 



Lime, L (Plats 12^ and 11^). JAxne was applied at the rate of 500 

 pounds of rock or 1,000 pounds slaked lime per acre every fourth year. 

 On plat in Field A during five years there was an average annual in- 

 crease of 41.4 pounds seed cotton per acre, and on plat in Field B during 

 three years an average increase of 22.4 pounds per acre, or on an aver- 

 age, an annual increase from both of the fields of 31.9 pounds per acre, 

 worth $0.81 annually per acre above the cost of the lime. 



Lime with Complete Fertilizer, N P K L (Plats 14^ and 122). 

 Where lime was used in combination with the three fertilizer constitu- 

 ents there was 84.9 pounds more of seed cotton produced per acre on an 

 average in Field A than where the normal (N P K) application was 

 used, and on Field B an average of 11.4 pounds more seed cotton per 

 acre, or an annual average 48.1 pounds per acre from the use of lime in 

 connection with the nonnal application of fertilizer. The average 

 annual increase due to the use of lime was worth $1.54 per acre above 

 cost of the lime. 



Taking the experiments as a whole, the average results show the fol- 

 lowing : 



That phosphoric acid is the plant food constituent that gave decidedly 

 the largest increase in yield and the greatest profit per acre. 



That potash and nitrogen in the amounts used in the experiments gave 

 only slight increase and ])rofit per acre, the former constituent on an 

 average gave a slightly greater profit per acre than did the latter. 



That lime when used alone had very little, if any, effect upon yield, 

 but whe7i applied in connection Avith a normal (IST P K) application of 

 fertilizer there was some better show for the lime. 



The main increased yields and profits, therefore, came from phos- 

 phoric acid ; the next most profitable constituent was potash, nitrogen in 

 the amount used only showing an average profit per acre above cost of 

 40 cents for the use of 10 pounds of nitrogen used with 28 pounds of 

 phosphoric acid and 10 pounds of potash. 



Effect of Varying Quantities of Nitrogen. — This part of the tests 

 was planned to determine the effect on the yield of cotton of varying 

 quantities of nitrogen, leaving the phosphoric acid and potash constant. 

 On one plat the nitrogen was reduced to one-half of the normal quan- 

 tity, making the application 5 pounds of nitrogen per acre or practi- 

 cally 1.9 per cent in the actual fertilizer mixture used. On two of the 

 plats it was increased by 2 and 3 times the normal quantity (10 pounds 

 per acre), making the application 20 and 30 pounds per acre respect- 

 ively, or on the basis of the fertilizer mixture 5.3 and 6.6 per cent. The 

 average results for five years on plats in Field A show the largest profit 

 per acre above cost of fertilizer to be from the fertilizer application 

 containing normal quantity of nitrogen in the several mixtures, while 

 the average results for three years in Field B the greatest profit was 

 from plats receiving a fertilizer application containing twice the normal 

 quantity of nitrogen in the mixture, or 20 pounds of nitrogen per acre. 



Taking the eight years experiments together the average annual re- 

 sults show an average increased yield per acre over unfertilized plats of 



