Soil Water Retention Curve from Saturated Hydraulic Conductivity for Sandy Loam and Loamy Sand Textured Soils

Abstract

Knowledge of the soil hydraulic properties is indispensable to solve many soil and water management problems related to agriculture, ecology, and environmental issues. Soil hydraulic properties are key factors that regulate the movement of groundwater and transport of solutes. The most important hydraulic properties of soils are the soil water retention curve (SWRC) and saturated hydraulic conductivity (ks). Determination of these hydraulic properties is needed for many studies and applications related to irrigation, drainage, water movement and solute transport in the soil. Although many advances are made for direct measurements of SWRC and ks, they are usually time consuming and costly. Some attempts have been made to indirectly predict these hydraulic properties. The objective of this study was to derive an empirical relationship to estimate soil water retention curve from saturated hydraulic conductivity. One hundred and one soil samples were collected from agricultural and forest sites at different depths, at different locations in the Pavanje river basin that lies in the southern coastal region of Karnataka, India. The saturated hydraulic conductivity was measured in the laboratory by variable falling head method using Permeameter and soil water retention curve data was obtained through pressure plate apparatus for all the agricultural and forest soils. Prediction accuracies were evaluated using coefficient of determination, root mean square error, mean error, Akaike Information Criteria, between measured and predicted values. The results obtained from the prediction of soil moisture retention curve from saturated hydraulic conductivity, shows that the developed relationship are reasonably useful to get the soil moisture retention curve for the soils of agricultural and forested hillslopes of the region under consideration.