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

ABSTRACT-Zeolite 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 ۰, ۴, ۸, and ۱۲ g kg-۱ 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, cm۳ cm-۳), while maximum value of a and b in sandy loam and silty clay soils, respectively occurred by zeolite application of ۸ g kg -۱ 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 ۸ g kg-۱ 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.

Keywords:

Hydraulic diffusivity , Sorptivity , Soil hydraulic parameters , Soil conditioner , Zeolite