ESTIMATION OF THE DRAINING SOIL-MOISTURE CHARACTERISTIC FROM STANDARD DATA AS RECORDED IN ROUTINE SOIL SURVEYS

An analytical expression describing the moisture retention characteristic was tested using multiple regression on 105 horizons in 34 representative soils from Greece, with textures from loamy sand to heavy clay. All samples were analyzed for particle size distribution, organic carbon content, carbonates content and dry bulk density. It was found that soil moisture retention by the studied soils can satisfactorily be described using a logarithmic model that incorporates simple soil properties such as saturation moisture content, clay and silt contents, and bulk density. The applicability of a simplified model (with saturation moisture content and clay content as the only soil parameters) to small watersheds and considering groups of soil horizons was apparent from the improved coefficients of determination. Homogeneity tests showed, however, that only 2 major groups of soil horizons could be distinguished, namely well-structured horizons and structureless to weakly structured horizons. Incorporating other soil properties in the regression analyses of these soil horizon groups produced only a slightly higher R(2)-value.