Prediction of soil moisture characteristics from mechanical analysis and bulk density data

Soil moisture characteristics can be established directly from the physical properties of soils such as mechanical analysis and bulk densities. Multiple regression equations were worked out by taking first fractions of sand (E₁), silt + clay (E' = E₂ + E₃) and bulk density (P), and second fractions of sand (E₁), silt (E₂), clay (E₃) and bulk density (P) as independent variables to predict the parameter b, the air-entry potential ψ_e and the saturation moisture content _s of the soil-moisture characteristics equation. Regression equations were tested for soils of different textural and structural compositions and showed good agreement between estimated and experimentally determined values.