250 SOILS AND FERTILIZERS 



which remove various amounts of fertility from the 

 soil. 



323. Two Systems of Farming Compared. — The 



losses of fertilitv from farms are determined bv the 

 crops and products sold, the care of the manure, and 

 the fertility in the products purchased and used on the 

 farm. If an account were kept of the income and 

 outgo of the fertility of farms it would be found that 

 with some systems, the soil is gaining in fertility, while 

 with others a rapid decline occurs. In studying the 

 income and outgo of fertility, it is necessary to calcu- 

 late the amount of the three principal elements, nitro- 

 gen, phosphoric acid, and potash in the crops and 

 products sold. For making these calculations tables 

 are given in Sections 178 and 290. In the handling of ma- 

 nure it is impossible to prevent losses, but it is possible 

 to reduce them to very small amounts. Hence in the 

 calculations, a loss of 3 per cent, is allowed for mechan- 

 ical waste, and for uneven distribution of the manure; 

 that is, in addition to the fertility sold from the farm a 

 loss of 3 per cent, is allowed for all crops raised and 

 consumed as food bv stock. 



On one farm the crops raised and sold are : Flax 40 

 acres, wheat 50 acres, oats 20 acres, barley 50 acres ; 

 no stock is kept, the straw is burned, and the ashes 

 are wasted. 



