CONSERVATION OF FERTILITY 



289 



Food and Fuel Purchased 



The manure produced and used on this farm results 

 in larger crop yields than is the case with exclusive grain 

 culture. The nitrogen gained by the clover and peas 

 more than balances the loss of nitrogen in other crops. 

 Experiments show that a rotation similar to this caused 

 an increase in soil nitrogen. 18 Manure, meadow, and 

 pasture all tend to increase the soil's humus and ni- 

 trogen. The losses of phosphoric acid and potash 

 are very small, averaging about a pound per acre of 

 each. The manure on this farm is continually bringing 

 into activity the inert plant food of the soil so that 

 every year there is a larger amount of more active 

 plant food, which results in producing larger yields 

 per acre. 



