MANURES. 147 



streams, and enriched by their overflow; 2d, lands 

 enriched, as sometimes, but rarely happens, by min- 

 eral waters flowing upon them from adjacent lands 

 during the winter and spring; 3d, lands in which there 

 is much fertilizing matter yet undecomposed, but in 

 which decomposition is constantly going on, so as to 

 keep pace with the wants of crops. Whoever is so for- 

 tunate as to own lands fertilized in either of these ways, 

 may, contrary to the general rule, take from them 

 without giving to them. There are few sitch lands, 



274. To the second class of lands — those producing 

 well loith manure — belong at least 9-lOths of all the 

 land in the world. The owners hold it on the simple 

 condition, that they are to put on as much as they 

 take off. They must furnish the raw material, out 

 of which their crops are to be manufactured, or they 

 can have no crops. They have indeed some choice, 

 in what form the raw material shall be supplied, and 

 in what crops it shall be returned. They may 

 supply it in the form of manure worth one mill a 

 pound, and receive it back in the form of wheat worth 

 two cents a pound ; or they may supply it in the con- 

 centrated form of guano, worth two cents a pound, 

 and receive several pounds of wheat for one of guano ; 

 but so far as the mineral ingredients of soils and crops 

 are concerned, they are to put on what they take off, 

 and as much of it. There is no choice here. With 

 the exception of a few favored soils before described, 

 this is the immutable law of farming. 



275. To the third class of lands — those that by no 



