PHYSICAL PROPERTIES OF SOIL. 227 



prairie. Nature never bestowed on man, soil of 

 greater capability of being made lastingly fertile, 

 than the sandy light soil of New England. 



296. It is evident that the terms of heavy and 

 light, given by the farmer to soil, do not refer to 

 their absolute weight (293). These distinctions de- 

 pend on firmness or consistency of soil. This pro- 

 duces a very marked difference in the fertility and 

 tillage of land. The terms light and heavy, mean 

 lighter or heavier to work. It is well known, clay 

 lands are heavy to work, sandy soil is the lightest 

 and easiest, next to this is a soil containing a small 

 portion of geine. All light soil becomes heavy 

 when wet, but it is a well ascertained fact, that 

 heavy soil, always becomes lighter by frost. Hence 

 the reason of breaking up with a plough before 

 winter. Moist earth then becomes frozen, and its 

 particles being driven asunder by frost, it becomes 

 lighter — in truth it has been found, that the consis- 

 tency of clay, is diminished nearly one-half by frost, 

 and loamy clay, one-half to two-thirds. It is essen- 

 tial to this change from heavy to light land, that the 

 soil be wet enough to freeze. It is well known, that 

 if by frost, the nature of the soil is thus changed, 

 that if it is ploughed while wet after freezing, the 

 labor of the fall ploughing is lost. A lasting injury 

 is done by ploughing land too wet. 



