The Wilting Coefficient and Its Indirect Determination

An investigation was made to determine whether the wilting coefficient of a soil can be computed from physical measurements of its moisture retentivity. A comparison of the wilting coefficient is made with the moisture equivalent, the hygroscopic coefficient, the moisture-holding capacity, and the mechanical analysis, for a series of soils ranging from sand to clay. From this comparison, a series of linear relationships is established, as expressed in the following equations, which form a means of computing the wilting coefficient when direct determinations are not feasible. {align*}Wilting coefficient &= {moisture equivalent{1.84 (1 ± 0.007)} \\ Wilting coefficient &= hygroscopic coefficient/0.68(1 ± 0.018) \\ Wilting coefficient &= {moisture holding capacity-21}}{2.90 (1 ± 0.021)}\\ Wilting coefficient &= 0.01 sand + 0.12 silt + 0.57 clay/1 + 0.025{align*} The second term of the quantity within the brackets shows the probable error of the relationship in each case, and constitutes a measure of the relative accuracy of the different methods.