FORAGE PLANTS 69 



farmer by increased yield. But this form of nitro- 

 gen is expensive. It averages 15 cents a pound 

 a high price to pay. 



By planting some nitrogen-gathering plant in 

 rotation with l his grain crops, the farmer puts 

 nitrogen back into the soil at a merely nominal cost. 

 Clover is one of the best soil restorers. It is a 

 nutritious pasture, or hay crop. Its roots go deep 

 and pulverize the soil. They gather nitrogen and 

 store it in nodules along their fibrous branches. 

 When growth ceases, the hay is cut and put into 

 the barn; those nitrogen-laden roots are left to 

 decay and enrich the soil for future crops. The 

 surface crop is worth much, for its nitrogenous 

 content is high, and when animals fatten on it, 

 much of its value is twice saved by careful spread- 

 ing of the stable manure on the fields. 



Four fifths of the air is nitrogen. Clover plants 

 have power to gather this element and store it in 

 the nodules on their roots. 



Long before farmers had ever seen the tubercles 

 on the roots of legumes (pod-bearing plants) they 

 knew that clover was the best means of renewing 

 worn-out land and enriching any soil. Fortu- 

 nately, experience was their guide, though, until 

 very recently, they followed blindly. One of 

 nature's best gifts to agriculture is this group of 



