SOIL WATER 



65 



68. Effect of texture on capillary movement. — The finer 

 the texture of a soil, other things being equal, the slower 

 is the movement of capillary water, but the water will 

 eventually rise higher in the soil of fine texture. This is 

 illustrated by the experimental data contained in the fol- 

 lowing table : 



Table 12. — Effect of Texture on Rate and Height of 

 Capillary Rise from a Water Table through Dry Soil 



One can see from the above data that although water rises 

 most rapidly in the sand, it does not rise as high as in the 

 other soils. This experiment was not continued long enough 

 to obtain the maximum rise in clay. Some experimenters 

 have been able to obtain a rise of water to a height of twenty- 

 six feet in a clay soil. 



69. Effect of structure on capillary movement. — Soil 

 structure by affecting the size of the pore spaces also affects 

 the rate of capillary movement. In general the condition 

 most favorable for plant growth is also best adapted to 

 capillary movement. Good tillage, tile drainage, farm 

 manure and lime all help to hasten the movement of water 

 in a soil. A very loose soil does not admit of capillary move- 

 ment and consequently cultivation of the surface prevents 

 water from coming to the surface of the ground from whence 

 it escapes into the air. Rolling, or otherwise compacting 

 the soil aids capillary movement and thus causes loss of 

 moisture from the surface soil. 



