WEARING OUT THE SOIL 



45 



which it uses up in its growth nitrogen, phosphoric 

 acid and potash. 



How Fertility May Be Retained. Progressive 

 farmers have learned that grain farming does not pay, 

 and they have gone into dairying and have prospered. 

 Why is dairy farming so 

 much better? Because the 

 grain and hay raised on 

 the farm are fed there and 

 returned again to the soil 

 in the form of barnyard 

 manure. Very little soil 

 matter is sold from the 

 farm. The proportion of 

 nitrogen, phosphoric acid 

 and potash in butter, 

 cheese, beef and pork is 

 very small for the amount 

 of feed consumed, as the 

 table following this chap- 

 ter will show. It will take 

 a long time to lessen to any great extent the amount 

 of these substances in the soil by dairy farming. 



Clover Enriches the Soil. Again, the dairy farmer 

 raises much clover, and clover, as you have already 

 seen, really enriches the soil by adding to it nitrogen 

 from the air. 



Summary. The wise farmer wastes nothing. If he 

 raises peas and corn, for the canning factory, he hauls 

 the vines and stalks back to his farm. If he grows 



Tubercles on the roots of velvet 

 beans In which nitrogen from the 

 air is stored up. 



