HO A YEAR IN AGRICULTURE 



methods of maintaining and increasing soil nitrogen in gen- 

 eral farming. 



The chief value of farm manure, aside from its supplying 

 organic matter, is its source of nitrogen supply, but, as was 

 noted above, it is impracticable under the present production 

 of live stock to look to this source for an adequate supply 

 of nitrogen. A more interesting and economic source is the 

 green manure from inoculated legumes. One ton of red 

 clover, when plowed into the average normal soil, will enrich 

 the soil by the addition of forty pounds of nitrogen, and 

 is, therefore, equal in nitrogen value to four tons of barn- 

 yard manure. The use of red clover, alfalfa, cow-peas, soy 

 beans, sweet clover, and other legumes provides the greatest 

 soil improvers, and has made possible a permanent economic 

 system of soil improvement. The use of high-priced com- 

 mercial nitrogen is artificial and unprofitable in general farm- 

 ing operations. 



A system of crop rotation that does not include a legume 

 crop which may be incorporated into the soil to furnish the 

 organic matter and the nitrogen supply is not a part of a 

 permanent system of soil improvement. 



Phosphorus. Doctor Hopkins calls phosphorus the master- 

 key to permanent agriculture. He says that phosphorus is 

 really what its name signifies light-bringer ; but that it is 

 a light which the American farmer has not seen. We have 

 exported to Europe each year enough phosphorus to double 

 the average crop production of the entire United States, if 

 it were all wisely used on our- soils. The tables given in 

 a previous paragraph show that ordinary soils are defi- 



