Soil erosion leads to degradation of hydraulic properties in the agricultural region of Northeast China

Agricultural erosion leads to degradation of hydraulic properties and further affects agroecosystem hydrological cycling. How such properties respond to intensities of erosion remain unclear, hindering the understanding of the mechanisms behind agroecosystem hydrological cycling. Herein, we investigated the variations in soil hydraulic and physical properties at different slope positions that subjected to various intensities of soil erosion (nonerosion, light erosion, moderate erosion, and heavy erosion) and deposition positions along a maize field in the agricultural region. The average erosion moduli were <200, 700, 1800 and 4200 t km-2 a-1 at the non-erosion, light erosion, moderate erosion, and heavy erosion sites, respectively. The measured soil properties included soil organic matter, bulk density, saturated hydraulic conductivity (Ks), soil water content, capillary moisture capacity, field capacity, parameters of the soil water retention curve and water-stable aggregates. Our results showed that organic matter, Ks, soil water content, capillary moisture capacity, field capacity and most parameters of soil water retention curve (i.e., ?r, ?s and n) decreased, but bulk density increased with soil depth at the eroding and non-erosion sites. Soil erosion decreased organic matter, Ks, soil water content, capillary moisture capacity, field capacity and the ability of soils to retain water but increased soil bulk density. The proportions of aggregates were not affected by soil depth or its interaction with soil erosion, while soil erosion decreased microaggregates but increased macroaggregates. Overall, in this study, agricultural erosion resulted in the degradation of soil hydraulic and physical properties, which may increase the risk of the agricultural ecosystem to suffer drought.