6o FARM CROPS 



legumes. The clovers, cowpeas, vetches and alfalfa 

 are all legumes. The tubercles are little, knotted, 

 wartlike growths on the roots of these plants, and 

 are caused by bacteria or germs as they are some- 

 times called. Instead of living in nests in trees like 

 birds, or in the ground like moles or worms, these 

 tiny germs, so small you can't see them with a 

 microscope, make their homes in the roots of these 

 plants. Nestling snugly together they live, grow 

 and multiply in their sunless homes. 



Through their activity the soil is enriched by the 

 addition of much nitrogen from the air. Just as 

 bees gather honey from the flowers and carry it to 

 the hives where they are prepared for it for their 

 long future use and for the use of others, so do 

 these root tubercles gather nitrogen in the air and 

 fix it in their root homes where it can be used by 

 other crops. Just as soon as the roots of legumin- 

 ous plants begin to push down into the soil the 

 bacteria or germs that make the tubercles begin to 

 build their homes in the roots, and in so doing they 

 add nitrogen to the soil. 



You now see the importance of growing such 

 crops as peas and clover on your land, for by their 

 aid you can constantly add plant food to the soil. 

 Now this much needed nitrogen is the most costly 

 part of the fertilizers that farmers buy every year. 

 If every farmer, then, would grow these tubercle- 

 bearing crops he would readily add to the richness 

 of his land, and at the same time would also escape 

 the necessity of buying so much expensive fer- 

 tilizer. 



One important thing about getting nitrogen 

 through the legumes is to have the soil in good 

 condition. The farmer must not only be able to 



