Estimating soil water retention characteristics from particle size distribution, organic matter percent, and bulk density

Regression models are presented for estimating soil‐water‐retention curves from particle‐size distribution, percentage of organic matter, and bulk density. Models were developed from the measured soil‐water‐retention curves of artificially packed cores (7.6×7.6 cm) of 43 soil materials. These soil materials included 13 agricultural soils. Curves predicted with these models approximated reasonably well the measured water retention of 61 Missouri soils. Because conventional methods of obtaining retention curves are expensive and time consuming, these equations will be valuable for modeling salt and water flow in soils and for estimating available water capacities.