GERMS IN THE SOIL 245 



(1) An abundance of vegetable matter for the germs to 

 feed on and to change into fertilizer. 



(2) A soil that is always moist, but well drained. 



(3) A soil kept so loose and well drained that air can 

 circulate in it. 



(4) An abundance of lime to keep the soil from becom- 

 ing sour. 



(5) A warm temperature. 



Germ enemies in the soil. The soil is not dead. It 

 swarms with living creatures. Some are friends, some foes. 

 If the farmer helps the friendly germs, they rapidly in- 

 crease and almost drive out some of the harmful germs. 

 But if he allows his land to remain long very wet or very 

 compact or very deficient in vegetable matter, his enemies 

 in the soil will increase to enormous numbers and his 

 friends will be banished. 



Nitrate destroyers. For example, there are germs that 

 are harmful because they change the valuable nitrates into 

 useless nitrogen gas. Thus they undo the good work that 

 the nitrate-forming germs have done. These harmful 

 kinds, or nitrate destroyers, do not thrive in a soil where 

 there is plenty of air. The farmer must fight these by the 

 means that help the friendly germs, by drainage, plowing, 

 cultivation, and by the addition of vegetable matter. 



