Effects of slaking and mechanical breakdown on disaggregation and splash erosion

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

Submitted to: European Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2017
Publication Date: 11/1/2017
Citation: Xiao, H., Liu, G., Zhang, X.J., Liu, P., Zheng, F., Zhang, J., Hu, F., Abd Elbasit, M.A. 2017. Effects of slaking and mechanical breakdown on disaggregation and splash erosion. European Journal of Soil Science. doi:10.1111/ejss.12482.
DOI: https://doi.org/10.1111/ejss.12482

Interpretive Summary: The contributions of different aggregate breakdown mechanisms to raindrop splash erosion are still unclear. This study was designed to investigate the effects of different soil disaggregation mechanisms on splash erosion. Loam clay soil, clay loam soil, and sandy loam soil 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 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 splash erosion rate increased with the increasing of rainfall kinetic energy in both deionized water and alcohol tests. The splash erosion rates for three types of soil followed the order of loam clay soil < clay loam soil < sandy loam soil, but the mean weight diameter (MWD) of disintegrated aggregates followed the opposite order. The splash erosion rates due to the effects of slaking and mechanical breakdown increased with an increase in 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. Slaking effect contributed more than 50% of splash erosion. The contribution rates of the slaking and mechanical breakdown to splash erosion depended on rainfall kinetic energy and soil type. These results demonstrated that reducing raindrop impact energy by increasing surface cover is an effective measure for decreasing soil erosion and runoff. This information will be useful to soil and water conservationists for controlling soil erosion.

Technical Abstract: The contributions of different aggregate breakdown mechanisms to splash erosion are still obscure. This study was designed to investigate the effects of different soil disaggregation mechanisms on splash erosion. Loam clay soil, clay loam soil, and sandy loam soil 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 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 splash erosion rate increased with the increasing of rainfall kinetic energy in both deionized water and alcohol tests. The splash erosion rates for three types of soil followed the order of loam clay soil < clay loam soil < sandy loam soil, but the mean weight diameter (MWD) of disintegrated aggregates followed the opposite order. The splash erosion rates due to the effects of slaking and mechanical breakdown increased with an increase in 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. Slaking effect contributed more than 50% of splash erosion. The contribution rates of the slaking and mechanical breakdown to splash erosion depended on rainfall kinetic energy and soil type.