Quantifying contributions of slaking and mechanical breakdown of soil aggregate to splash erosion for different soils from the Loess Plateau of China

Authors: XIAO, HAI - Northwest Agricultural & Forestry University; LIU, GANG - Northwest Agricultural & Forestry University; ZHANG, QIONG - Northwest Agricultural & Forestry University; FENLI, ZHENG - Northwest Agricultural & Forestry University; Zhang, Xunchang; LIU, PULING - Northwest Agricultural & Forestry University; ZHANG, JIAQUIONG - Northwest Agricultural & Forestry University; HU, FEINAN - Northwest Agricultural & Forestry University; ABD ELBASIT, MOHAMED - Agricultural Research Council Of South Africa

Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/30/2017
Publication Date: 1/16/2018
Citation: Xiao, H., Liu, G., Zhang, Q., Fenli, Z., Zhang, X.J., Liu, P., Zhang, J., Hu, F., Abd Elbasit, M.A. 2018. Quantifying contributions of slaking and mechanical breakdown of soil aggregate to splash erosion for different soils from the Loess Plateau of China. Soil & Tillage Research. 178:150-158. https://doi.org/10.1016/j.still.2017.12.026.
DOI: https://doi.org/10.1016/j.still.2017.12.026

Interpretive Summary: The information to assess the aggregate disintegration mechanisms during splash erosion is scant. This study was conducted to quantify the contribution of the mechanism for aggregate disintegration on splash erosion. Six types of soil with five soil textures were used in this study. Soil aggregate stability was determined by the LB (Le Bissonnais)-method. Deionized water was used to simulate the combined effect of slaking and mechanical disaggregation, while alcohol was used to estimate the sole contribution of the mechanical breakdown. Simulated rainfall with intensity 60 mm h-1 were applied at five fall heights (0.5 m, 1 m, 1.5 m, 2 m and 2.5 m) to achieve different rainfall kinetic energy. The results indicated that slaking had the most effect on aggregate breakdown, and followed by mechanical breakdown, while chemical dispersion in slow wetting with deionized water is the weakest breakdown mechanism. The splash erosion rates due to the effects of slaking and mechanical breakdown increased with the increasing of rainfall kinetic energy. The contributions of the slaking and mechanical breakdown to splash erosion decreased for the former while increased for the latter as rainfall kinetic energy increased. The contribution of mechanical breakdown had a power function relationship with rainfall kinetic energy and was most significantly correlated with RSI (relative slaking index)/RMI (relative mechanical breakdown index). An equation describing the power and linear relations for the contribution of mechanical breakdown with rainfall kinetic energy and RSI/RMI, respectively, developed in this research can be used to estimate the contribution of mechanical breakdown. The results of this research would provide useful information on how to conserve soil aggregates and soil physical properties.

Technical Abstract: The information to assess the aggregate disintegration mechanisms during splash erosion is scant. This study was conducted to quantify the contribution of the mechanism for aggregate disintegration on splash erosion. Six types of soil with five soil textures were used in this study. Soil aggregate stability was determined by the LB (Le Bissonnais)-method. Deionized water was used to simulate the combined effect of slaking and mechanical disaggregation, while alcohol was used to estimate the sole contribution of the mechanical breakdown. Simulated rainfall with intensity 60 mm h-1 were applied at five fall heights (0.5 m, 1 m, 1.5 m, 2 m and 2.5 m) to achieve different rainfall kinetic energy. The results indicated that slaking had the most effect on aggregate breakdown, and followed by mechanical breakdown, while chemical dispersion in slow wetting with deionized water is the weakest breakdown mechanism. The splash erosion rates due to the effects of slaking and mechanical breakdown increased with the increasing of rainfall kinetic energy. The contributions of the slaking and mechanical breakdown to splash erosion decreased for the former while increased for the latter as rainfall kinetic energy increased. The contribution of mechanical breakdown had a power function relationship with rainfall kinetic energy and had the most significant correlation with RSI (relative slaking index)/RMI (relative mechanical breakdown index). An equation describing the power and linear relation for the contribution of mechanical breakdown with rainfall kinetic energy and RSI/RMI, respectively, developed in this research can be used to estimate the contribution of mechanical breakdown. The results of this research will help to improve the soil erosion prediction models.