IDEAL FERTILIZERS 71 



form of fertilizer, and says: "These statements serve to 

 show that extensive and far-reaching chemical changes 

 are wrought by bacterial action. It is obvious that the 

 more favorable the soil conditions are for the growth of 

 bacteria, the more intense will be their activity and the 

 greater the changes brought about." 



Fungi 



Fungi range in size from microscopic forms but little 

 larger than bacteria to immense toadstools. They are of 

 much higher organism, multiplying by the production of 

 spores (seeds) in place of the simple division of bacteria. 

 "Many soil fungi assist in decomposing organic matter, 

 especially in the earlier stages of decomposition. They 

 are particularly active in acid soils in which many bac- 

 teria cannot work." 



Animal Life 



Protozoa Protozoa are one-celled organisms that in 

 greenhouse conditions sometimes become so numerous 

 as to destroy an appreciable number of nitrifying bac- 

 teria, but we are not likely to feel their influence in the 

 field. 



Root Knot or Nematodes The adult nematode or eel 

 worm is about three-hundred ths of an inch in length. 

 It punctures the roots and breeds therein, causing the for- 

 mation of galls and inducing disease and decay. This 

 trouble is popularly known as root knot. Rotation of 

 crops and flooding the land are the only means of con- 

 trol known at the present time. 



