ROTATION OF CROPS. 



57 



suffer by the sale of individual crops. We will now con- 

 sider briefly the losses during a rotation. 



The conservation of plant food on a farm is generally 

 effected by confining the exports to corn and meat, the 

 rest of the produce being consumed by the stock, and the 

 manure returned to the land. Let us assume that a farm 

 is managed on the four-course system, and that the 

 average crops obtained per acre are — swedes, 14 ton ; 

 barley, 40 bush.; seeds (half clover, half grass), 3 ton of 

 hay ; and wheat, 30 bush. Further, that nothing is sold 

 save corn and meat; that 2 bush, both of wheat and 

 barley are returned to the land as seed ; that 700 lb. of 

 linseed cake are fed with each acre of swedes ; that 110 lb. 

 of oats are purchased per acre per annum for the horses. 

 Finally, that half a ton of straw is fed per acre in the course 

 of the rotation, and the rest used as litter. Tii£L.aaiLwill in 

 this case suffer the following losses of ]>if^irt> jphj^^jg^ 

 acid, and potash, in the course of a ^^ ;^ears' ^i"fetab«)n ' 



LOSSES PER ACRE DURING A FOUBr^CQPJ^E ^jmOT^^ * X 



V 



•7 



