242 SOILS AND FERTILIZERS . 



329. Two Systems of Farming Compared. The 



losses of fertility from farms are determined by 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 is occuring. In studying 

 the income and outgo of fertility, it is necessary to 

 calculate the amounts of the three principal elements, 

 nitrogen, phosphoric acid, and potash in the crops and 

 products sold. For making these calculations tables 

 are given in Sections 172 and 293. In the handling 

 of manure 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 al- 

 lowed for mechanical waste, and for uneven distribu- 

 tion of the manure ; that is, in addition to the fertility 

 sold from the farm a mechanical loss of 3 per cent, is 

 allowed for all crops raised and consumed as food by 

 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. 



In addition to the nitrogen removed in the crops 

 other losses must be considered. Experiments have 

 shown that when exclusive grain farming is practiced, 

 for every pound of nitrogen removed in the crop, four 

 pounds are lost from the soil in other ways. See 



