1921. 



PUBLIC DOCUMENT — No. 31. 



17 a 



scarcely a perceptible difference in the yield of corn. So 

 varied are our New England soils! 



The Effect of Nitrogen, Phosphoric Acid and Potash on Corn 

 and Grass. — An opportunity was offered during the past two 

 seasons to study the same crop on three of our experimental 

 fields, — namely, the nitrogen field, the potash field and the 

 phosphate field. During 1919 these three fields were in corn. 

 In one case the limiting factor was nitrogen, in another potash 

 and in another phosphoric acid. On all of these fields there 

 were certain plots that have received incomplete mixtures; for 

 example, the check })lots on the potash field received no potash. 

 The rates of application of the several plant-food elements per 

 acre are shown in the following table : — 



Field. 



Total Nitrogen (Pounds) 



Total Phosphoric Acid 

 (Pounds). 



Total 



Potash 



(Pounds). 



Nitrogen Field, 

 Potash Field, . 



Phosphate Field, 



45, . . . 



[ 39 (from nitrate), 



( 20 (from tankage), 



f 56 (from nitrate), 



I 20 (from ammonia) 



[ 14.6 (from organic nitrogen) 



80 (from acid phosphate), 

 57J^2 (from acid phosphate), 

 30 (from tankage), 



^96, 



125 

 135 



150 



The yields of hard corn follow, the figures representing 

 bushels per acre: — 



The significance of these figures lies in their uniformity. The 

 average product of complete fertilizer treatment on all three 

 fields is practically the same. 



During the past season these same fields were in grass and 

 clover, the seed mixture sown being the same in all cases. The 



