26 FIRST PRINCIPLES OF AGRICULTURE. 



ical character, which is very important in determining 

 fertility. 



Sandy Soils. Land which contains over seventy per 

 cent of sand is called sandy. Such soils are not only 

 poor in plant-food, but they can absorb and retain but 

 little moisture. The soil, loosely held together, permits 

 the rapid passage of water, and the stony particles readily 

 absorb heat. In hot, dry seasons, the crops are soon 

 parched; in wet seasons, however, these same properties 

 enable the soil to dry quickly, thus permitting, if suffi- 

 cient food is provided, the growth of maximum crops, 

 when they would be destroyed from excess of mois- 

 ture on soils of a more dense or tenacious character. 

 Sandy soils are easy to work, and may be cultivated 

 when quite wet without injury, and are well adapted 

 to quick-growing crops; when overlying clay subsoils, 

 they are susceptible of a high degree of fertility. 



Clay Soils. A clay soil is one which contains over 

 fifty per cent. of clay. A clay soil is almost the reverse 

 of a sandy soil. The finely divided particles adhere so 

 closely as to make the access of air, moisture, and 

 warmth, difficult; they are, therefore, called cold and 

 tenacious. They are hard to work, and, unless well 

 drained, crops are liable to suffer both in wet and dry 

 seasons ; in wet seasons because the moisture is not freely 

 movable, and in dry seasons because the land becomes 

 so hard as to prevent the penetration of roots. They 

 are well adapted to the growth of cereals and grasses. 



Limestone Soils. The term " lime " or " calcareous," 

 is applied to a soil when it contains over twenty, per 

 cent of lime. Limy soils are usually of a good char- 



