The Influence of Texture on the Moisture Characteristics of Soils

Summary The available‐water capacity (AWC) of soil profiles in the field may be estimated by ( a ) measuring the thickness of each soil horizon; ( b ) assessing its texture; and ( c ) summing the products of the thickness of each horizon and the mean values of AWC for the relevant textural classes. (This mean value of AWC was calculated from the average particle‐size composition and from a relationship between particle size composition and AWC.) Estimates of AWC using this method were compared with measured values for each of 39 soils. When a 21 textural‐class system was used to describe the soils, the mean error (the error of the estimated AWC value relative to the measured value) was ±10 per cent and with a 12 class system the mean error was ±17 per cent.