Soil development and management effects on hydraulic properties along a granitic soil toposequence in southern China

Abstract

A profound understanding of the effects of natural soil development and anthropogenic land management on soil hydraulic properties is essential for soil productivity and water conservation. The objective of our research was to explore the effects of soil development on soil bulk density (BD), pore size distribution, saturated hydraulic conductivity (Ksat), and soil water retention characteristics under horseweed grass (Erigeron canadensis) and corn (Zea mays)-rapeseed (Brassica napus) rotation systems in weathered granitic soils in southern China. Pore size classes determined were macropores (effective diameter > 1000 μm), coarse mesopores (effective diameter 60–1000 μm), fine mesopores (effective diameter 10–60 μm), and micropores (effective diameter < 10 μm). Soil samples from each treatment were collected to a depth of 40 cm in 10 cm increments. The results showed that Ksat was highest in Entisols (6.08 cm h−1) and lowest in Alfisols (2.58 cm h−1), and these values were averaged across management systems and depths. The saturated water content was 12.8% higher in Alfisols than that in Entisols. With soil development, soil water retention increased for all measured soil water pressures. The highest macroporosity as well as coarse and fine mesoporosity were recorded in Entisols, while the highest microporosity was found in Alfisols. Improvement in soil physical and hydraulic properties was seen in the horseweed grass system (HG) compared with that in the corn-rapeseed rotation system (CR). The bulk density was 6% lower for the HG than that for the CR. The HG had 30% higher Ksat and 10.3% greater saturated water content than the CR. The HG also had 15.2% increased macroporosity compared with the CR, which may enhance water infiltration and reduce runoff loss.