402 



THE PRINCIPLES OF SOIL MANAGEMENT 



neutral or slightly alkaline soil furnishes the most 

 favorable conditions for bacterial growth. The activi- 

 ties of many soil bacteria result in the formation of 

 acids which are injurious to the bacteria themselves, 

 and, unless there is present some basic substance 

 with which these can combine, bacterial development 

 is inhibited by their own products. This is one of the 



Fig. 110. Spring-toothed walking cultivator. For thorough, shallow tillage. 



reasons why lime is so often of great benefit when ap- 

 plied to soils, and especially to those on which legumi- 

 nous crops are growing. For the same reason, the 

 presence of lime hastens decay of organic matter in 

 certain soils, and the conversion of nitrogenous ma- 

 terial with a minimum loss into compounds available 

 to the plant. As showing the value of lime in the 

 process of nitrification, it has been pointed out that 

 in the presence of an adequate supply of lime the 

 availability of ammonium salts is almost as high as 





