MINERAL MATTERS RESTORED BY MANURE. 



By the cultivation of cereals, and the removal of the 

 corn-crops, the arable surface soil loses a certain por- 

 tion of corn-constituents, which must be restored to it 

 by farm-yard manure, if the future crops are to be kept 

 up to the mark of the preceding ones. 



This restoration is effected by the cultivation of fod- 

 der-plants, such as turnips, clover, grass, &c., on which 

 the cattle on the farm are fed, and the constituents of 

 which are drawn, in large proportion, from the deeper 

 layers of the ground, where the roots of the cereals 

 cannot penetrate. 



These fodder plants are consumed either on the field 

 itself, as turnips in England, or in the stalls. A frac- 

 tion of the nutritive substances contained in these 

 plants remains in the body of the animals fed upon 

 them, while the remainder, ejected in the form of solid 

 or liquid excrements, constitutes farm-yard manure, the 

 principal bulk of which, however, consists of straw 

 which has served for litter. 



In Germany animals are not fed upon potatoes 

 themselves, but upon the refuse from the distilleries of 

 potato spirits, which contains all the nutritive substances 

 taken away from the soil in the potato crop, together 

 with the constituents of the barley-malt that have 

 been used in the process of mashing. 



Since the whole of the straw taken away in the 

 crops of the preceding rotation is, as a general rule, 

 returned to the arable soil in the shape of farm-yard 

 manure, the field is, at the outset of the new rotation, 

 as rich as before in the conditions for the production of 

 straw ; and there exists, under these circumstances, no 

 ground for a diminution of the straw-crops. 



With regard to the clover, turnips, potato- waste, 

 &c., upon which the stock on a farm is fed, there re- 

 mains, as already stated, in the bodies of the horses, 

 cattle, &c., and full-grown animals in general (which 

 no longer materially increase in weight), only a very 

 small fraction of the constituents of the food consumed ; 

 but in the young cattle sent to market, in the bodies of 

 the sheep, in the milk and cheese, a portion of these 



