COMPOSITION OF SOILS AND THEIR ACTION. 55 



Principle 1. All plants exhaust the soil. 



" 2. All plants do dot exhaust the soil equally. 



" 3. Plants of different kinds do not exhaust a soil in 



the same manner. 

 " 4. All plants do not rest jre to the soil the same quan 



tity or quality of manure. 

 " 5. All plants do not foul the soil equally. 



From these established principles, the following 

 are legitimate inferences. First. No soil can nour- 

 ish a long-continued succession of crops without ex- 

 haustion. There would seem to be no exceptions 

 to this, unless the case of river alluvion, such as that 

 of the Genesee Flats, for example, may be consid- 

 ered such. But in this case the annual oveiilowing, 

 either entire or partially, renews the deposite of 

 fertile matter ; or the water, by permeating the soil, 

 divests it of any injurious principles it may have re- 

 ceived from previous crops. The position may 

 therefore be considered sound ; and the man who 

 crops continually, without making corresponding 

 returns to the soil, will experience its truth in the 

 rapid decrease of his crops grown on such land. 

 • Another inference, and the second, is, that while 

 one kind of crop exhausts the soil by drawing most of 

 its nourishment direct from the earth, and returning 

 nothing of consequence to it, other kinds, deriving a 

 large part of their nourishment from the atmosphere, 

 and returning to the earth much vegetable matter, 

 exhaust it scarcely any, if at all. To illustrate this, 

 let us take grains and clover, or grains and roots 

 with large tops, such as the beet, ruta-baga, &c. 

 The cultivation of the Avhite grains, such as wheat, 

 &c., probably wear out land as rapidly as any crop 

 the farmers of the North can cultivate. This, in 

 part, may be attributed to the ripening of the seeds ; 

 but more, we think, to the plants deriving a large 

 part of their nutriment from the earth, and but little 

 from other sources ; while, at the same time, the 

 return they make of vegetable matter is the small- 

 est possible quantity. Clover would seem to obtain 



