Effect of Slope, Rainfall Intensity and Mulch on Erosion and Infiltration under Simulated Rain on Purple Soil of South-Western Sichuan Province, China

Abstract

Purple soil is widely distributed in the hilly areas of the Sichuan basin, southwest China, and is highly susceptible to water erosion. The triggering of this process is related to slope, rainfall intensity and surface cover. Therefore, this study assesses the effects of different simulated rainfall intensities with different slopes on hydrological and erosional processes in un-mulched and mulched purple soils. Results show that the sediment and water losses increased with an increase of rainfall intensity and slope steepness. Generally, the slope contribution (Sc) on water and sediment losses decreased with increasing rainfall intensity and slope steepness under both un-mulched and mulched soil. In un-mulched conditions, water losses were independent of slope steepness (Sc < 50%) during the highest rainfall intensity. However, in mulched soil, the higher contributions of slope (Sc) and rainfall (Rc) were found for water and sediment losses, respectively, i.e., >50%, except during the increase in slope steepness from 15 • to 25 • under the highest rainfall intensity (120 mm·h −1 ). The effectiveness of mulch was more pronounced in reducing sediment losses (81%-100%) compared with water losses (14%-100%). The conservation effectiveness of mulch both decreased and increased with slope steepness for water and sediment losses, respectively, under higher rainfall intensities. Water infiltration and recharge coefficient (RC) decreased with an increase of slope steepness, while with an increase in rainfall intensity, the water infiltration and RC were increased and decreased, respectively, in both un-mulched and mulched soil. On the other hand, mulched soil maintained a significantly (α = 0.05) higher infiltration capacity and RC compared to that of the un-mulched soil.

Innovative Pro-Smallholder Farmers’ Permanent Mulch for Better Soil Quality and Food Security Under Conservation Agriculture

“…Figure 1 indicates that runoff is further exacerbated by increases in rainfall intensity. These results are in line with findings by Khan et al [24], who reported an increase in sediment and water loss with an increase in rainfall intensity and slope steepness, in a laboratory experiment conducted under rainfall simulation using Calcaric Regosols. Xin et al [25] also conducted a laboratory rainfall simulation experiment using black soils (Udic Argiboroll) at 7% fixed slope, five levels of residue cover (bare, 15%, 35%, 55%, and 75%) and four rainfall intensities (30 mm/h, 60 mm/h, 90 mm/h, and 120 mm/h).…”

“…The kinetic energy impact of raindrops on soil surface in high intensity storms causes increased soil particle detachment and sediment loss, excess runoff and surface sealing [23]. According to Khan et al [24], the triggering of this process is related to slope, rainfall intensity and surface cover. The detached soil particles are transported away from the site of drop impact through runoff, which exacerbates land degradation [1,5].…”

Infiltration and Soil Loss Changes during the Growing Season under Ploughing and Conservation Tillage

“…As moisture content increases, the infiltration value decreases, until it reaches its theoretical minimum, which is dependent on the soil texture and structure. In reality, this minimum value is not a constant but rather a function of rainfall intensity [17]. Higher rainfall intensity triggers a higher final infiltration rate, as described by Rose [18].…”

Integrated Effects of Land Use and Topography on Streamflow Response to Precipitation in an Agriculture-Forest Dominated Northern Watershed

“…It might be because forested soil has stronger and more persistent water repellency due to the high organic matter contents under dry conditions [41]. In addition, the steep slope gradients of the forest as compared to the pasture could have played a role, which results in a shorter time for water remaining on the soil because of the gravity effect lower water storage capacity on steep slopes [42]. However, it should be noted that the subsurface flow and total streamflow in FW were both higher than AW.…”