.58 ROTATION OF CROPS. 



and, finally, even a want of fertility j but that, by the restoration 

 of these materials, the fertility may be sustained, and even in- 

 creased. 



After so many striking proofs respecting the origin of the con- 

 stituents of plants and of animals, and of the use of alkalies, of 

 phosphates, and of lime, can we entertain the slightest doubt of 

 the principles upon which a rational system of agriculture must 

 depend ? 



Does the art of farming, then, depend upon anything else than 

 the restoration of a disturbed equilibrium ? 



Is it conceivable, that a rich fertile land, with a flourishing 

 trade, which has for centuries exported the products of its soil in 

 the form of cattle and of corn, can retain its fertility, if the same 

 trade do not restore to its land, in the form of manure, the con-, 

 stituents abstracted from it, and which cannot be replaced by the 

 atmosphere ? In such a case, would not the same fate await this 

 land as that which befel Virginia, upon the soil of which wheat 

 and tobacco can no longer be cultivated ? 



In the large towns of England, the products of English as well 

 as of foreign agriculture are consumed ; and to supply this great 

 consumption, the constituents of the soil necessary to the plants 

 are removed with them, from an immense surface of land, to 

 which they are not again returned. The domestic arrangements 

 peculiar to the English render it difficult, perhaps even impossi- 

 ble, to collect the immense quantity of phosphates (the most im- 

 portant ingredients of the soil, although present in it in small 

 quantity), which are daily sent into the rivers in the form of urine 

 and of solid excrements. We have seen upon the fields of Eng- 

 land exhausted of their phosphates, the most beneficial effects pro- 

 duced upon the crops by the introduction of bones (phosphate of 

 lime) from the Continent ; in some cases, the crops on the soil 

 were doubled by the use of this manure, as if by a charm. 



But if this exportation of bones be continued on the same scale 

 as at present, the German soil will become gradually exhausted ; 

 and the loss will be perceived to be greater than at first is ap- 

 parent, when it is considered that a single pound weight of bones 

 contains as much phosphoric acid as a whole hundred- weight 

 of corn. 



