Model of the Soil-Moisture Characteristic

A procedure is proposed by which the soil-moisture characteristic of sandy soils can reasonably be established as ψ=ψ_c(θ/$$$)^−β, where ψ_c is the air-entry capillary suction in bar, β is an empirically determined constant, θ is the volumetric moisture content of the soil and θ_c is the value of θ at saturation. Only a single measurement of ψ at θ is needed. The value of β can be estimated as β=26.5(λ₂/λ₁)^1.786, where, λ₁ and λ₂ are the percentage sand and silt of the soil. The procedure is useful when a reliable curve is not available. Statistical test of the β-model established from the experimental observation of twelve samples of soil mixtures indicates its validity.