Important Soil Characteristics Relevant to Irrigation

Abstract

Water in the soil profile is very seldom under equilibrium conditions. Many forces act upon the soil solution in a continously changing manner, thus causing redistribution of water. As water always moves in the direction of decreasing potential, the rate of flow is determined by the potential gradient and the ability of the soil to transmit water. Mathematically, the water flux is expressed by the Darcy equation:

$$ v = - K\nabla \Phi $$

where v is the water flux, K is the soil hydraulic conductivity, and ∇ Ф is the gradient of the total potential field in which the water is moving. The minus sign expresses the fact that water is flowing in the direction of decreasing potential.