THE: SOIL AND WATER 



whether or not the particles are porous. The smaller the particles 

 and the more porous they are, the greater the quantity of water 

 held. Humus and other organic matter, being porous, increase 

 the water retained considerably. 



The water held by drained soils may be determined by placing 

 the soil in tubes which can be divided into sections, as in the ex- 

 periment of King cited, though the tubes need not be so large. 

 After the soil has been saturated and is fully drained, the water is 

 determined in the different sections. Unless the tube is sufficiently 

 long, the upper sections will not be fully drained. The length of 

 tube required depends upon the character of the soil. The follow- 

 ing figures of Schloesing show the quantity of water held by fully 

 drained soils : 



Weight of water in 

 100 parts of drained soil 



Coarse sand 3.00 



Fine sand 7.30 



Calcareous sand 32.00 



Clay soil 35-oo 



Forest soil 42.00 



The state of consolidation of soil affects the water held by it. 

 Closely packed particles will retain at least twice as much water 

 per unit of volume as particles loosely packed. Sandy soil has its 

 capacity increased by rolling, and that of clay soil is reduced by 

 pulverization. 



