Effect of tillage on soil erosion before and after rill development

Abstract

Tillage 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.

Exploring the interaction of surface roughness and slope gradient in controlling rates of soil loss from sloping farmland on the Loess Plateau of China

“…Thus, the reduction effect of SSR on the runoff volume and sediment yield would change and diminish with increasing slope gradient. This has also been confirmed by Zhao, Hou, and Wu () who found that reduced soil erosion only occurs during the overland flow erosion process due to soil deposition in the depressions. In addition, depressions and mounds contribute to rill generation and increase soil erosion during the latter stage of rainfall for tillage with depressions and mounds.…”

Modeling Soil Erosion With Evolving Rills on Hillslopes

“…The rill orientation angle is an important characteristic of rill network planform, which generally shows a trend of decrease with space and time (Bennett & Liu, 2016; Gómez et al, 2003; Shen et al, 2015). At early times, the small rills emerge very quickly and prefer the path of minimum energy dissipation (Frei & Fleckenstein, 2014; Stefanovic & Bryan, 2009; Zhao et al, 2018). The average orientation angle of the small rills is assumed the same at different cross sections due to the uniformly distributed microtopography, which is about 10–75° on planar hillslopes (Brunton & Bryan, 2000; Gómez et al, 2003; Shen et al, 2015).…”

“…Spatially, it shows a bell‐shaped trend along slope length, transiting from an increase to a decreasing trend (Bennett & Liu, 2016; Bruno et al, 2008; Schneider et al, 2013; Shen, 2015). Previous studies show that water flow initially concentrates in areas of depression (Cheraghi et al, 2018; Zhao et al, 2018) where the soil does not have enough cohesion or strength to resist the hydraulic stress and there is a greater possibility for rill initiation (Hofer et al, 2012; Nord & Esteves, 2005). The empirical understanding suggests that the main factors governing rill density include the rainfall intensity, interrill flow erosivity, the erodibility of the soil, and the erosion per unit area.…”

Rill morphological change characteristics and influencing factors on different soil types in the Loess Plateau, China

“…An increase in rill length is mainly caused by an increase in the number of rills and rill head advance under traceable erosion (Schneider et al, 2013;Wu et al 2018). An increase in rill depth is mainly caused by further retrogressive erosion of rills due to undercutting, caused by runoff shear dispersion and the reemergence of rill head undercutting in rills (Gomez et al, 2003;Zhang et al, 2017;Zhao et al, 2018). A higher level of soil cohesion, due to higher levels of clay and organic matter content, make it easier for soil to form a mass structure, especially as clay content in a soil can significantly enhance the anti-dispersion ability of the wet soil layer.…”