218 THE SYSTEM OF FAEM-TARD MANURING. 



he regulates the quantity according to certain facts. If 

 he has found by experience that a certain quantity of 

 farm-yard manure will restore his land to its original 

 fertility, and that more copious manuring will fail to give 

 larger crops, in proportion to the additional supply, or to 

 the cost incurred in collecting the manure, he will stop at 

 the smaller quantity. 



Hence it cannot be regarded as a mere accident that the 

 farmer at Cunnersdorf contented himself with 180 cwt. 

 of farm-yard manure, while the farmer at Oberbobritzsch 

 laid 314 cwt. upon his field. 



But if the quantity of manure to be applied is not 

 dependent upon chance or caprice, ])ut is regulated by 

 the object in view, it is manifest that the proceedings of 

 the farmer are governed by a law of nature unknown to 

 him, except by its effects. 



It is in the composition and condition of the soil that 

 we must seek the law which regulates the quantity of 

 farm-yard manure required, at the outset of a fresh rota- 

 tion, to restore a field to its former fertility ; and it is not 

 difficult to see that this quantity must always be propor- 

 tionate to the effective dung-constituents already present 

 in the soil ; a field largely abounding in them takes less 

 manure than a poor field to give the same increased 

 produce. 



Now, as farm-yard manure owes its most active con- 

 stituents to clover, turnips, and the grasses, the inference 

 is pretty clear that the quantity of this manure required 

 on a field is in an inverse ratio to the produce of clover, 

 turnips, or grass, which the field can give when unma- 

 nured. 



The Saxon experiments show that this inference cannot 

 be far from the truth, in one respect at least ; for on 

 comparing the produce of clover given by the unmanured 



I 



