干旱区生态环境知识资源中心

Vegetation and its succession can change the parameters of soil water repellency (SWR) due to the change in amount and composition of soil organic matter. This hypothesis was tested in natural and agricultural environments in Germany, Hungary, and Slovakia. The parameters investigated were the extent (determined by the repellency indices RI, RIc, and RIm) and persistence (determined by the water drop penetration time and water repellency cessation time) of SWR, as well as the potential wettability index of organic matter in sandy soils. The SWR parameters and soil organic carbon (SOC) content increased in the course of primary succession at Mehlinger Heide, Germany, and Sekule, Slovakia. Dye tracer experiments undertaken at Sekule revealed contrasting flow patterns: (a) preferential flow in water-repellent soil under biological soil crust and grass and (b) piston flow in wettable soil that consists almost of pure quartz sand. The effective flow cross section decreased, and the degree of preferential flow increased in the course of primary succession at Sekule. No consistent trend of the SWR parameters and SOC was observed in the course of secondary succession at Csolyospalos, Hungary. This is the first time that differences between trends in SWR parameters due to primary and secondary successions were observed and related to the composition of SOC and extracellular polymeric substances. It can be concluded that dynamics of soil organic matter composition during the succession controls SWR.