A new method for estimating soil water repellency index

The soil water repellency index, R, is calculated from the ethanol sorptivity, S-e, and water sorptivity, S-w, using an equation: R = 1.95 S-e/S-w. In the older method, Se and Sw were measured in pairwise arrangements to reduce the influence of spatial heterogeneity of soil properties, and one value of R only was calculated from one pair of S-e and S-w measurements. The new method to estimate R takes into account all the measured values of water and ethanol sorptivity, i. e., m x n values of R are to be calculated from m values of S-w and n values of S-e. The results of the t-test revealed that there is not a statistically significant difference between the means of both samples at the 95.0% confidence level for all four studied soils. It was found using the F-test that there is not a statistically significant difference between the variances of samples estimated by the older and new methods at the 95.0% confidence level for all but one (grassland soil) studied soils. Comparison of R values taken in sandy soil under different vegetation cover in Sekule, southwest Slovakia, revealed that the average values of R estimated using the new method increased with vegetation succession, i. e., Pure sand < Glade soil < Grassland soil < Pine-forest soil, while the mean values of R estimated using the older method changed in the order: Pure sand < Grassland soil < Glade soil < Pine-forest soil. It seems that an increase in the number of R values processed can result in the more reliable mean values of R at the sites with high spatial heterogeneity of soil properties.