ESTIMATING SOIL-WATER CHARACTERISTICS OBTAINED BY BASIC SOIL DATA - A COMPARISON OF INDIRECT METHODS

Continuing earlier investigations of the junior author accuracy of soil water characteristics is tested which are obtained from easily accessible data like texture, soil carbon content and porosity data. Nomographic and algebraic procedure based on selection of similar particle size distribution curves are compared with measured moisture retention curves. The same comparison is conducted with values obtained using regression models for the parameters of Van Genuchten approach. Analysis of the mean standard deviations al pF 4.2 shows an accuracy of 2.1 Vol-% for the regression, model of the Van Genuchten parameters and 2.4 or 3.2 Vol-% for the algebraic and nomographic selection methods respectively. The comparison gives at low soil water suctions (pF 1.8) values of 2.8 and 3.3 Vol-% for the algebraic and the nomographic procedure and 5.0 Vol-% for the regression model.