AMERICAN AGRICULTURE. 



CHAPTER" f.'^l V , 



SOILS." 



SOILS are those portions of the earth's surface, which 

 contain a mixture of mineral and vegetable or animal sub- 

 stances, in such proportions as adapt them to the support of 

 vegetation. Rocks are the original basis of all soils, which 

 by the convulsions of nature, or the less violent but long 

 continued and equally efficient action of air, moisture and 

 frost, have been broken into fragments more or less minute. 

 There are various gradations of these changes. 



THE TEXTURE or SOILS. Some rocks exist in large 

 boulders or rounded stones, that thickly overspread the surface 

 and mingle themselves with the earth beneath it, giving to 

 it the name of a rocky soil. The smaller sizes but equal 

 prevalence of the same materials, give to the surface where 

 they abound, the character of a stony soil. A third and 

 more minute division is called a gravelly soil ; a fourth is a 

 sandy soil ; a fifth constitutes a loam ; and a sixth, in which 

 the particles of earth are reduced to their greatest fineness, 

 is known under the name of a clay soil. The two first 

 mentioned, are not properly distinct soils, as the only support 

 of any profitable vegetation, is to be found in the finer earth 

 in which the rocks and stones are embedded. In frequent 

 instances, they materially benefit the crops, in the influence 

 produced by the shade, moisture, and protection from winds, 

 afforded by them ; and by the gradual decomposition of such 

 as contain lirne, potash and other fertilising materials, they 

 contribute to the support of the soil. This last effect is 

 aided by the apparently worthless vegetable life which they 

 yield to the living mosses that cling to their sides and every 



