Unsaturated Hydraulic Functions of Some Aridisols and Ultisols

Horizontal absorption experiments were conducted in specially designed plexiglass columns on three soil samples from a Semi-arid region (Haryana) and another three from a humid region (Assam). Unsaturated water transmission parameters, viz, soil water diffusivity [D(θ)] and ‘capillary conductivity [K(θ)] were evaluated. Scaled soil water diffusivity [D*(θ)] versus reduced moisture content (θ) relationship was developed to estimate D(θ) values of any soil from its easily determinable characteristic length. The values of K(θ), as obtained from D(θ) and moisture retention [h(θ)] data, for all the six soil samples wert compared with those estimated, through pore size distribution based approach of Green and Corey. There was a big difference between the observed and predicted values of K(θ) for heavy textured soils, whereas the light textured ones showed a relatively better agreement between the two sets of values, particularly at high moisture content