FORAGE CROPS. 



369 



*' This difference in the amount of accumulated nitrogen in 

 clover-land appears still more strikingly on comparing the total 

 amounts of nitrogen per acre in the different sections of the two 

 portions of the i i-acre fields : — 



Percentage of nitrogen per acre : — 



1st 6 inches. 2d 6 inches. Jd 6 inches, 



lbs. lbs. lbs. 



* I. In soil, clover twice over .. . 3,350 .... 1,875 •••• ')3^S 

 I II. In soil, clover once mown 



and seeded afterward 4)72.5 .... Z)35° .... ^12.25 



Equal to ammonia : — , 



* 1. Clover twice mown 4,05° 2,i75 1,600 



t II. Clover seeded 5,725 4,050 4,70O 



* I. Nitrogen in roots of clover 



twice mown 24^ 



+ II. Nitrogen in clover, once mown 



and grown for seed afterward . 512- 



I. Weight of dry roots per acre 



from Soil 1 1,4932 



II. Weight of dry roots per acre 



from Soil II 3, 622 



* Total amount of nitrogen in i 



acre, 12 inches deep, of Soil I 5,249^ 

 f Total amount of nitrogen in 1 



acre, 12 mches deep, of Soil II 8,126^ 



* Equal to ammonia 6,J74J 



f Equal to ammonia 9,867 



Excess of nitrogen in an acre of 

 soil, 12 inches deep, calculated 

 as ammonia in part of field 

 mown once and then seeded. 3,492^ 



" It will be seen that not only was the amount of large clover 

 roots greater in the part where clover was grown for seed, but that 



