Effect of tillage on soil erosion before and after rill development

Abstract

AbstractTillage has a large effect on soil surface microtopography and consequently on soil erosion. Here, we measured soil and water loss from soil prepared by contour tillage (CT) and reservoir tillage (RT), and to analyse why tilled slopes produce more sediment run‐off. Rainfall experiments (90 mm/hr) were carried out to simulate the overland and rill flow erosion processes. Soil type is silt clay loam. Results showed that CT and RT reduced surface run‐off by 60% compared with a smooth slope during overland flow, whereas only a small reduction in run‐off occurred during rill flow. Sediment erosion from CT was reduced by about 30–60% compared with a smooth slope for both overland and rill flow erosion processes. Although RT also resulted in reduced sediment erosion during overland flow, sediment erosion increased by 25% during rill flow, leading to an overall increase in sediment flow on the RT‐treated slope. For slopes with CT, sediment production depends on the ridges, but furrows limit sediment transport. For slopes with RT, sediment production depends on the depressions, but once the depressions fill with sediment, rainwater outflowing from the depressions cause rill flow erosion and greater sediment loss compared with CT. Our results suggest that sediment and run‐off differences for different surface microtopographies induced by tillage are significant, especially during the rill flow erosion process. Future studies should address rill erosion on tilled sloped land with different microtopographies to better determine how rills are triggered and change during rainfall.