Evaluation of an analytical method for relationship between soil hydraulic diffusivity and sorptivity under zeolite application

ABSTRACTZeolite is used to improve the soil hydraulic properties, i.e., soil hydraulic diffusivity (D) and sorptivity (S) that should be determined. A simple method that relates S to D was evaluated by horizontal water absorption experiment in sandy loam, loam and silty clay soils and zeolite application rates of 0, 4, 8, and 12 g kg1 soil. Results indicated that zeolite application was not effective on the a and b values of hydraulic diffusivity function (D=aEXP(bθ), θ is the soil water content, cm3 cm3), while maximum value of a and b in sandy loam and silty clay soils, respectively occurred by zeolite application of 8 g kg 1 soil. The values of a and b for loam soil were not influenced by zeolite application rates. Sorptivity for sandy loam soil was reduced by zeolite application rate, while minimum value of S for loam and silty clay soils occurred at zeolite application rate of 8 g kg1 soil. It is indicated that indirect determination of S for different soil textures and zeolite application rates were closely similar to the direct determination of S. Therefore, by determination of S value by simple horizontal absorption test at two different initial soil water contents or two different absorption suction heads in tension infiltrometer  the values of Ds and α for hydraulic diffusivity function (D=Dsθα) can be estimated.