Effects of different tillage types on soil erosion in the hilly red soil region of Southeastern China

Le résumé fourni par la source

Tillage methods have a significant influence on soil erosion on sloping farmland, particularly in critical areas such as the Yangou Small Watershed in the hilly red soil region of South China. To investigate the effects of tillage practices on soil erosion, this study considered runoff, sediment yield, soil loss, and changes in soil water content before and after twelve selected high-intensity rainfall events impacting five plots with different tillage types. Specifically, 5× 20 m plots covered by bare land (BL), trifolium repens + citrus tree (TR), cross-slope tillage + citrus tree (CT), down-slope tillage + citrus tree (DT), and standard terrace + citrus tree (ST) were analysed. Based on long-term monitoring, runoff and sediment of every plot were measured using collection tanks, while soil water content was continuously recorded by automatic sensors. The results showed that the bare land, used here as a control plot, had the highest runoff, sediment, and soil loss, which were 4 times, 228 times, and 234 times those of the second-highest plot (DT), respectively. The runoff of TR, DT, and ST was almost the same, indicating no impact of those tillage methods on surface flow. The sediment yield of TR and ST was comparable, about half of that of CT, but still much lower than that of DT. The soil losses of TR, ST, and CT were about 0.01 kg, which was approximately one-quarter of that of DT, indicating the high erosivity potential of this last tillage method. During the rainfall events characterised by reduced intensity, all four tillage methods performed well. However, the soil loss of CT increased slightly, and DT performed the worst in soil conservation during very high-intensity rainfall events, suggesting that control strategies should focus on sediment generated during extreme events. ST showed the lowest sediment yield among all tillage methods, ranging between 0.01 and 0.1 kg, and pointed out that this tillage method should be preferred in soil conservation planning. Using an experiment at the plot scale, sensitivity analyses demonstrated that, although there are treatment-related differences under the selected high-intensity rainfall events, the rainfall intensity structure, particularly I30, maximum rainfall intensity, and EI30, can be associated with soil loss. Down-slope tillage is the most erosion-prone tillage practice among the four methods, whereas Trifolium repens cover and standard terrace are the most erosion-resistant methods, likely due to the reduced streamwise slope typical of terraces. By comparing four tillage methods and cover practices used in the hilly red soil region of southeastern China, this study provides field-based references for site-specific land management and soil conservation planning under high-intensity rainfall conditions.

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