Determination of Small-Scale Spatial Heterogeneity of Water Repellency in Sandy Soils

The degree of water repellency in soils is commonly characterized by the contact angle (CA). For its determination, disturbed and homogenized soil samples are used. Thus, information about the small-scale spatial heterogeneity of soil water repellency is lost. We modified the sampling technique of the sessile drop method to allow the determination of the CA on particles located at their original positions, reflecting the natural wetting properties of the site. The proposed preparation technique further allows the determination of small-scale variability of water repellency (millimeter to centimeter scales) along transects with a length of approximately 1 m or more. Hence, the small-scale spatial distribution of water repellency within a soil profile or transect can be determined and its impact on physical, biological, or chemical processes in soil can be evaluated.