172 PROFITABLE DAIRYING 



$20, if it is carefully saved and returned again 

 to the land. 



How dairying enriches the soil. Again, the 

 wise farmer raises much clover, alfalfa, cowpeas 

 or soy beans for forage plants. These plants are 

 legumes and have associated with them micro- 

 scopic germs called bacteria, which live in little 

 nodules on the roots of these plants. To con- 

 vince yourself of this fact, pull up any one of 

 the above-mentioned plants and examine its roots 

 for these nodules. They are not always to be 

 found, but usually can be. Now, what is the use 

 of these germs? The soil contains but small 

 quantities of nitrogen, a substance without which 

 no plant can grow, no animal thrive, indeed, no 

 life exist. This small quantity of nitrogen is 

 combined in the soil with other elements in a 

 form readily soluble in water, and in this dis- 

 solved condition finds its way into the plant 

 through the roots. It is then built into the body 

 of the plant. Animals get all their nitrogen 

 from the plants on which they feed, and the 

 plants get theirs from this small store of nitrogen 

 in the soil. 



The work of bacteria in the legumes. The air 

 is four-fifths nitrogen, but, strangely enough, 

 neither plants nor animals can make use of this 

 abundant supply of "free" nitrogen, as it is 

 called. But the little germs living in the nodules 



