Water Movement and Conductivity Capacity in Unsaturated Conditions of Cultivated Soils

Abstract

The aim of this study is to propose equations to estimate water flow in cultivated clay soils. The water movement parameters were represented as unsaturated hydraulic conductivity K(θ)[LT-1], water diffusivity D(θ) [L2 T-1] and intrinsic permeability, k [L2 ] in plant-root zone. Two alluvial clay soils located at northern Nile Delta were used to apply the assumed equations. The soils were planted with cotton yield during 2014 season. The soil profiles were different in their salinity, clay % and source of irrigation water. The equations which assumed to predict soil water movement parameters considered only the matric potential as a driving force in capillary pores, and gravitational potential that is critical for the large, non-capillary pores. An equation for predicting a suggested parameter called conductivity potential or conductivity capacity of soil pores Kp(θ) [M L-1T-3] (erg. cm-3.sec-1 or joule. m-3 sec-1) was derived in vadose zone. Data of pore size distribution were obtained for the investigated
soil profiles using water retention data. The calculated K(θ), D(θ) and k values were conformable to the common measured ranges, indicating the applicability of the proposed equations for predicting water movement parameters in cultivated clay soils.