Vol18 No.5: 1222-1234
【Title】Effects of soil conservation practices on soil erosion and the size selectivity of eroded sediment on cultivated slopes
【Author】XU Lu1,2; ZHANG Dan1*; PROSHAD Ram1,2; CHEN Yu-lan3; HUANG Tian-fang4; UGURLU Aysenur1
【Addresses】1 Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China; 2 University of Chinese Academy of Sciences, Beijing 100049, China; 3 Liangshan Company of Sichuan Provincial Tobacco Co., Xichang 615000, China; 4 Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China
【Corresponding author】ZHANG Dan
【Citation】Xu L, Zhang D, ProshadR, et al.(2021) Effects of soil conservation practices on soil erosion and the size selectivity of eroded sediment on cultivated slopes. Journal of Mountain Science 18(5). https://doi.org/10.1007/s11629-020-6569-2
【Abstract】Soil conservation practices can greatly affect the soil erosion process, but limited information is available about its influence on the particle size distribution (PSD) of eroded sediment, especially under natural rainfall.In this study, the runoff, sediment yields, and effective/ultimate PSD were measured undertwo conventional tillage practices,downhill ridge tillage(DT) and plat tillage (PT)and three soil conservation practices, contour ridge tillage (CT), mulching with downhill ridge tillage (MDT), and mulching with contour ridge tillage (MCT) during 21 natural rainfall eventsin the lower Jinsha River.The results showed that (1) soil conservation practices had a significant effect on soil erosion. The conventional tillageof DT caused highest runoff depth (0.58 to 29.13 mm) and sediment yield (0.01 to 3.19 t hm-2). Compared with DT, the annual runoff depths and sediment yields of CT, MDT and MCT decreased by 12.24%-49.75% and 40.79%-88.30%, respectively.(2) Soil conservation practices can reduce the decomposition of aggregates in sediments. The ratios of effective and ultimate particle size (E/U) of silt- and sand-sized particles of DT and PT plots were close to 1, indicating that they were transported as primary particles, however, values lower/greater than 1 subject to CT, MDT and MCT plots indicated they were transported as aggregates. The ratios of E/U of clay-sized particles were all less than 1independently of tillage practices. (3) The sediments of soil conservation practices were more selective than those of conventional tillage practices. For CT, MDT and MCT plots, the average enrichment ratios (ERs) of clay, silt and sand were 1.99, 1.93 and 0.42, respectively, with enrichment ofclay and silt and depletion of sand in sediments. However, the compositions of the eroded sediments of DT and PT plots were similar to that of the original soil. These findings support the use of both effective and ultimate particle size distributions for studying the size selectivity of eroded sediment, and provide a scientific basis for revealing the erosion mechanism in the purple soil area of China.
【Keywords】Natural rainfall; Runoff and sediment yield; Soil particle size distribution; Enrichment ratio; Purple soil