Numerical Analysis of Solute Transport from Trickle Sources in a Combined Desert Soil–Imported Soil Flow System

One of the alternative solutions to the problems associated with the agricultural use of stony desert soils is to apply imported soil material into trenches that are aligned along the crop rows. The purpose of the present study was twofold: first, to analyze the effect of two imported soil materials available in the Arava Valley of Israel on the movement and spread of water and solute originating from multiple trickle line laterals, taking into account the trench geometry, the discharge of the trickle line laterals, the pattern of the plant root distribution, and the spatial heterogeneity of the hydraulic properties of the local soil; and, second, to extend the analyses to hypothetical imported soil materials characterized by different sets of hydraulic parameters (saturated conductivity, K s , and the van Genuchten soil parameters α and n , related to the soil9s pore size distribution). Results of the present study suggest that in the case of relatively low-conductive imported soil materials, a wide and shallow trench may leach the solute below a horizontal control plane more efficiently than a narrow and deep trench, while the opposite is true for high-conductive imported soil materials. Combinations of the threshold values of K s and α above which a narrow and deep trench is more efficient in solute leaching than a wide and shallow trench calculated here suggest that, for a given n , a relatively large threshold value of K s may compensate for a relatively small threshold value of α, particularly when n is relatively large.