236 Bacteria in Relation to Country Life 



fying results from the use of pure cultures of various 

 nitrogen-fixing, decay aild nitrifying bacteria, our present 

 state of knowledge seems to offer a greater assurance of 

 success in stimulating the activities of soil bacteria by 

 soil-improvement. Better moisture conditions, as well 

 as better conditions of aeration, more and better humus, 

 and a better supply of mineral plant-food will not only 

 stimulate the increase of soil bacteria, but will, also, in- 

 tensify their virulence. They will thus be enabled to 

 cause more decay, more nitrification, and more nitrogen- 

 fixation in a given time. On the other hand, the mere 

 introduction of efficient bacteria of whatever class, 

 without previous soil-improvement, will fail to yield 

 the desired results, since the bacteria introduced will 

 soon deteriorate under the unfavorable soil conditions. 



