r>s 



EG YP TIAS A GRIG UL TURE. 



it causes a constant circulation of the soil water by disturb- 

 ing the equilibrium between surface tension and gravity. 

 In soils having growing crops, this stream of water is 

 more towards the plant roots than towards the surface, as 

 the aerial part of the plant prevents evaporation from the 

 soil surface. A land stocked with plants loses much water 

 by the transpiration of plants, but evaporation from the 

 surface of the soil is less than on bare land. 



The following table shows the relative powers of capil- 

 larity of the soils which have already been considered. 



RELATIVE CAPILLARITY OF CERTAIN SOILS, DETERMINED 

 BY THE RISE OF WATER IN TUBES AFTER STANDING FOR SOME TIME. 



THE BIOLOGICAL PROPERTIES OF THE SOIL. 



The biological properties of the soil are those characters 

 which it possesses in virtue of the various forms of animal 

 and plant life found in the soil. Without the presence of 

 living bodies, the soil is practically an inert mass unsuited 

 for the cultivation of crops. In fact, the weathering of 

 the soil particles for the preparation of available plant 



