114 THE INVISIBLE WORLD 



become rich in the same themselves. Therefore 

 when the roots decompose in the soil, they add to 

 the soil still further richness. 



However large the crop of clover, in growing it 

 makes the soil richer and better. The larger the 

 crop, the richer it leaves the soil. From personal 

 experience I know that, in the right latitudes, two 

 crops of the medium red clover may be taken from 

 the same field in one season. They shall each aver- 

 age two and a half tons to the acre five tons 

 from every acre in one season. Yet the soil shall 

 be made better and richer to produce some other 

 crop the next season. By frequently rotating 

 clover with other crops, the soil is kept in a high 

 state of fertility, and the farmer's ledger counts 

 on the right side. It is because soil microbes with 

 this crop do their best work. 



The decay of all animal and vegetable bodies on 

 the surface of the earth is a means of enriching 

 the soil. But in this decomposition microbes are 

 the chief actors. The microbes of putrefaction 

 seize hold of all such bodies and literally reduce 

 them to atoms. The carbon then unites with oxy- 

 gen from the air and rises into the atmosphere as 

 carbonic acid. But the nitrogen unites with other 

 elements, forms nitrates which are absorbed by, 

 and enrich, the soil. Without the aid of these mi- 

 crobes all dead animal and vegetable bodies would 

 remain undissolved, and soon so encumber the 

 earth as to render it unfit for the abode of human 

 beings and the lower animals. But by their speedy 



