Life in the Soil 127 



that they have the power which no green plant has, to get 

 carbon from chemical combinations, and they can get 

 carbon from Hme carbonate. To preserve bacterial life 

 in the soil, then, we need to have the soil in a feebly alka- 

 line state, and hence, when growing the legume crops on 

 the soil frequently in the rotation, we must avoid acid 

 conditions by an occasional application of lime. 



This brings us to the next branch of this 

 Denitrification . ^. ^. t -i • u • ^ ui 



mvestigation. In sous rich m vegetable 



decay, there is often a serious loss of nitrogen through 

 rapid oxidation and the consequent escape of ammoniacal 

 gas into the atmosphere. The constant exposure of the 

 soil, in the clean cultivation of cotton in the South and in 

 single cropping in any part of the country, without the use 

 of recuperative crops, is one of the greatest causes of this 

 loss. Bulletin 53, of the Minnesota Station, shows how 

 great the loss is in the constant cultivation of wheat year 

 after year there. While a crop of wheat harvested re- 

 moved but 24.5 pounds per acre, it was found that the 

 actual loss of nitrogen from the soil was 171 pounds per 

 acre. But when wheat was grown in a rotation, in which 

 clover was used as a means for the restoration of the or- 

 ganic matter, there was a great gain instead of loss. The 

 same result has been shown in the constant clean cultiva- 

 tion of cotton in the South, as well as in the same practice 

 in many sections in the cultivation of tobacco. These 

 natural losses are easily preventable by a proper rotation 

 of crops. 



We have already pointed out the danger of great loss 

 of nitrogen, through the improper handling of the ma- 

 nures of the farm, by leaving them to ferment in piles and 



