Nitrates in Soils. 



103 



Small as these amounts of nitric nitrogen are the yield 

 of corn on plot 9 was a mean of 8,000 Ibs. of water-free 

 matter per acre. On another plot where the yield was 

 11,440 Ibs. of water-free matter per acre the nitric nitro- 

 gen was reduced as low as 1.44C parts per million in the 

 first foot and .726 parts in the second foot. 



It must be understood that, in these cases the demands 

 for nitrogen were so urgent that the plants \vi-re taking it 

 up almost as rapidly as it could he produced, leaving the 

 amounts so low, as the figures show. 



119. Nitrates of Fallow and Cropped Ground. In the 



table which follows are given the amounts of nitrates 

 found under different crops and, at the same time, undar 

 immediately adjacent fallow ground which had been cul- 

 tivated and kept free from weeds. 



If the mean amount of nitrates in the surface foot of the 

 fallow ground and under the crops are expressed in pounds 

 per acre they stand 473.65 to 10.88. This difference is 

 enough for 85 bushels of oats per acre, where the ratio of 

 grain to straw stands as 3 to 5. 



