Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Plants, Soils, and Climate

Department name when degree awarded

Irrigation Science

Committee Chair(s)

Sterling A. Taylor


Sterling A. Taylor


W. J. Staple


D. S. Stevenson


G. N. Denike


The movement of water in soils is of great importance to all of us but especially to agriculturalists. If it were not for this movement plants would not be able to survive in soil. If the moisture moves too freely in the soil insufficient water can be stored to supply plants during dry periods. The movement of water through soil may remove plant nutrients or accumulate salts in soil horizons.

The flow of water in soil has been studied extensively for many years. Water movement can occur in either saturated or unsaturated soil. Darcy's law can be used with a fair degree of accuracy in saturated soil. However, when tension or suction is developed in the soil-water system as in unsaturated flow, this law is difficult to apply. In unsaturated soil the flow is no longer directly proportional to pore size and gradient but also depends on the film thickness around the soil particles. The film thickness varies with the degree of unsaturation in the soil.

The availability of water to plants depends partly on the ability of water to move through the soil to the plant roots. After the wetting of a soil this movement to the plant roots must occur through unsaturated soil. Two factors are important in this moisture movement, the rate of movement and the total amount that will move to the plant root. The amount of water that will move depends on the volume of soil that will supply water and its moisture content.

The object of this investigation is to measure the amount of water that can be removed from a layer of soil by certain extracting tensions, the rate of movement, and the zone from which the water is removed for certain soils.



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