290 THE FARMER OF TO-MORROW 



manure be plowed under in the spring and 

 be given a chance to ferment. 



But to grow the legumes successfully, it is 

 necessary that the bacteria which inhabit the 

 nodules on the roots of these plants are given 

 a chance to work amid sanitary surroundings. 

 The soil must be "sweet" else the nitrogen- 

 fixing bacteria, which may add as much as 200 

 pounds of nitrogen to an acre of land in an 

 ordinary clover crop, will die. And, in 

 addition, unless the decaying mold of the soil 

 can feed these same bacteria on starches in 

 return for their nitrates, the bacteria are use- 

 less as a factor in soil fertility. 



The knowledge of bacteria, molds and en- 

 zymes as affecting fertility is still fragmentary. 

 Scientists have isolated a few forms or "races" 

 of microscopic plants and animals and de- 

 termined their part in soil fertility and the 

 conditions under which they thrive. There 

 are other forms which, under conditions favor- 

 able to their culture, render the most fertile 

 soils sterile. Professor Hall well says that the 

 farmer of the future must domesticate these 

 unseen life-forms, encouraging the helpful 

 organisms and doing away with those that are 

 harmful. 



