>0,S LESSONS IN AGRICULTURE 



LESSON LXIT 



CLOVER AND OTHER LEGUMES 



On some mild day in March, when the wind is not 

 blowing and the ground is thawing, we shall sow clover 

 seed in our wheat field, number 2, on the farm. It will 

 require about one bushel of seed to sow the ten acres, 

 and our seed will cost about $7 or $8. We must charge 

 this to our expense account to be balanced up with 

 profits later. 



Restoring nitrogen to the soil. Nitrogen is the 

 element which under ordinary conditions of fanning 

 is likely to be soonest exhausted. The farmer's atten- 

 tion must early be turned to methods of restoring nitro- 

 gen to his soil. Of course the best method of restoring 

 all elements of fertility to the soil is by the use of barn- 

 yard manure, but it is not always possible to do this. 

 There is a class of plants, however, called legumes, that 

 have the power of adding nitrogen to the soil. Peas, 

 beans, clovers, alfalfa, etc., belong to this class. It is 

 the purpose of this lesson to discover how these plants 

 add nitrogen to the soil. 



Nitrogen in the air. Air is composed largely of two 

 gases, nitrogen and oxygen. About one-fifth of the air 

 is oxygen and the other four-fifths is nitrogen. It is 

 the oxygen that causes iron to rust, coal to burn, or 

 wood to decay. On the other hand, nitrogen does not 

 combine readily with other substances. It dilutes the 

 oxygen of the air by being mixed with it, and prevents 

 the oxygen from burning up everything in the world, 



