90 The Bulletin 



or 131 pounds of 16 per cent acid phosphate, which is equal to 21 

 pounds of phosphoric acid per acre. Larger quantities than the above 

 of phosphoric acid did not add to the yields of corn when the quantities 

 of nitrogen and potash remained the same. 



Effect of Different Quantities of Potash. — The potash experiments 

 show the effect on the yield of com and stover of varying quantities of 

 potash, the nitrogen and phosphoric acid remaining constant. On one 

 plat only one-half the normal quantity of potash was applied or 1.1 per 

 cent in the fertilizer mixture, or 2.25 pounds of potash per acre. On 

 two other plats tAvo and three times the normal quantities were given, or 

 9 and 13.5 pounds per acre respectively. This would make the appli- 

 cation of potash on the several plats 2.25, 4.5, 9, and 13.5 pounds. The 

 results in all of the fields are uniform in showing that the larger quan- 

 tities were not as profitable as the normal amount, IV2 per cent in the 

 fertilizer mixture, or 4I/2 pounds per acre. Neither was a very small 

 quantity, % per cent in the fertilizer mixture, or 2.25 pounds per acre, 

 as y^rofitable or as effective in increasing yields as the normal quantity. 



The indications are that II/2 per cent of potash is all that is needed 

 for corn in this soil when used in connection with the regular quantities 

 of nitrogen and phosphoric acid in the normal corn mixture. 



The results further throw light on the comparative values of nitrogen 

 and potash for corn on this soil and give unquestionably a more impor- 

 tant place to nitrogen than potash. 



Effect of Varying Quantities of Fertilizer. — The results in the lower 

 section of Table IX show the effect of increasing and decreasing the 

 normal fertilizer application on yields, the nomial (N P K) being 300 

 pounds of a mixture containing 7 per cent phosphoric acid, 3 per cent 

 nitrogen and 1^/^ per cent potash. The applications were at the rate of 

 150 pounds per acre (Vl*!^ P K) ; 300 pounds per acre (N P K) ; 450 

 pounds per acre (31/2 N P K) ; 600 pounds per acre (2 N" P K) ; 900 

 pounds per acre (3 N" P Iv). The results in all the fields show in- 

 creased yields and profits for all the quantities of fertilizer. The 

 amount of fertilizer varied from 150 to 900 pounds per acre. During 

 two years in Field A the largest profit was from 300 pounds of the fer- 

 tilizer mixture per acre, the average yield being 37.7 bushels per acre, 

 at a profit of $14.16 over cost of fertilizer on the basis of com alone, 

 or $20.67 on the basis of com and stover. During four years in Field 

 B 450 pounds of fertilizer gave the largest profit, the yield of corn 

 being 39 bushels per acre, this being 27.3 more than was yielded by the 

 unfertilized plat. The profit per acre from this application on this 

 field was $16.80 on the basis of corn alone, or $25.37 on the basis of 

 value of both corn and stover. From one year's results in Field C, the 

 largest increase in yield and profit resulted from an application of 450 

 pounds of the norm.al fertilizer mixture per acre. 



RESULTS WITH COWPEAS AT STATESVILLE. 



An examination of the yields on the plats in Field C given in Table 

 X will show that there was a decrease in yields for each of the four 

 years. This is due, in part, to weather conditions and time of planting. 

 Tn 1904 the pea crop had the land throughout the entire growing sea- 

 son and without the draft of a previous crop on the available plant food 



