引用本文:安娟,陈新军,宋红丽.近地表水文条件对横坡垄作坡面褐土团聚体流失的影响[J].土壤学报,2020,57(6):1411-1421. DOI:10.11766/trxb201908210276
AN Juan,CHEN Xinjun,SONG Hongli.Characteristic of soil aggregate loss on cinnamon soil slope within contour ridge system under different soil surface hydrological conditions[J].Acta Pedologica Sinica,2020,57(6):1411-1421. DOI:10.11766/trxb201908210276
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近地表水文条件对横坡垄作坡面褐土团聚体流失的影响
安娟1, 陈新军2, 宋红丽1
1.山东省水土保持与环境保育重点实验室;2.临沂市水利局
摘要:
以横垄褐土坡面为研究对象,基于室内模拟降雨试验,就3种近地表水文条件下(自由入渗、土壤饱和与渗流)团聚体(≥5、2~5、1~2、0.5~1、0.25~0.5、<0.25 mm)在不同雨强(30, 60, 和90 mm·h-1)下的流失规律进行了探究。结果表明:(1)团聚体流失量的差异表现为:渗流>土壤饱和>自由入渗,且随雨强变化土壤水分饱和与渗流对团聚体流失的贡献较水势差分别显著增加2.02倍~3.71倍和1.28倍~2.51倍;(2)土壤饱和与渗流的存在致使2~5、1~2、0.5~1 mm团聚体的流失比例增加46.74%~121.19%,而削弱了90%以上0.25~0.5 mm团聚体的流失;(3) 土壤饱和与渗流使>0.5 mm团聚体的富集率增加了23.77%~215.80%,但导致0.25~0.5 mm团聚体的富集率减少45.07%~68.90%,主要是因为0.25~0.5 mm团聚体在侵蚀过程中发生了团聚;(4)平均重量直径是反映自由入渗与土壤饱和条件下团聚体流失的重要指标,而渗流条件下则为分形维数; (5)雨强对团聚体流失的影响在自由入渗条件下体现的最明显,尤其是对2~5 mm团聚体。研究结果有助于深入理解横坡垄作对坡面侵蚀过程的作用机制,为横垄措施的合理利用提供科学依据。
关键词:  团聚体流失粒径分布  富集率  流失团聚体特征指标  渗流  雨强  横坡垄作
基金项目:国家自然科学基金项目(41301292, 41977067, 41601086)
Characteristic of soil aggregate loss on cinnamon soil slope within contour ridge system under different soil surface hydrological conditions
AN Juan1, CHEN Xinjun2, SONG Hongli1
1.Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection, College of Resources and Environment, Linyi University, Linyi;2.Linyi Conservancy Bureau, Linyi
Abstract:
【Objective】Soil moisture content is one of the major factors determining degrees of soil aggregate breakdown, which alters the distribution of particle sizes in sediment. Soil surface hydrological condition reflects the spatial distribution of soil moisture content at slope, and strongly affects the characteristic of soil aggregate loss. However, previous researches focused on the influence of soil surface hydrological condition on runoff and sediment yield process within flat tillage system, and limited information are available about effect of soil surface hydrological condition on soil aggregate loss, especially under seepage condition in a contour ridge system. While, contour ridge system is an effective soil conservation practice used worldwide.【Method】In this study, simulated rainfall experiment was conducted to determine the lost characteristic of six size soil aggregates(≥5, 2-5, 1-2, 0.5-1, 0.25-0.5, and<0.25 mm) under three soil surface hydrological conditions (free drainage, soil saturation, and seepage) and three rainfall intensities (30, 60, and 90 mm•h-1)for cinnamon soil in a contour ridge system.【Result】Results showed that soil aggregate loss was in order of seepage>soil saturation>free drainage, seepage and soil saturation had 1.44-4.22 and 0.26-3.12 times soil aggregate loss greater than free drainage condition. Contribution rate of the existence of soil saturation and seepage for soil aggregate loss was significantly 2.02-3.71 and 1.28-2.51 times higher than that of water potential difference with the change of rainfall intensity. There was significantly difference in the loss distribution of soil aggregate among soil surface hydrological conditions. Soil saturation and seepage resulted the loss percentage of 2-5, 1-2, and 0.5-1 mm aggregate increased by 46.74%-121.19%, but weakened more than 90% of 0.25-0.5 mm aggregate loss. In addition, soil saturation and seepage increased by 23.77%-215.80% for the enrichment rate of >0.5 mm aggregate, but induced the enrichment rate of 0.25-0.5 mm aggregate decreased by 45.07%-68.90%. Because 0.25-0.5 mm aggregate occurred re-aggregate during erosion process, and the transport capacity of 2-5 mm aggregate was strengthened under the interaction of soil saturation and seepage. For the four characteristic indices of lost soil aggregate (the mean weight diameter, geometric mean diameter, mean weight soil specific area, and fractal dimension), difference in the mean weight diameter was the largest among soil surface hydrological conditions. The mean weight diameter was better indicator characterizing soil aggregate loss under free drainage and soil saturation conditions, while it was fractal dimension under seepage condition. Soil aggregate loss pronouncedly increased with the increase of rainfall intensity under free drainage, soil saturation, and seepage conditions. Among, effect of rainfall intensity on soil aggregate loss was the most pronounced under free drainage condition, and rainfall intensity had the greatest influence on 2-5 mm aggregate.【Conclusion】Soil saturation and seepage significantly enhanced soil aggregate loss, and showed more pronounce influence on the loss of lager size aggregate. These findings enhance our understanding of erosion mechanism for soil surface hydrological condition and contour ridge influence on soil erosion process, and supply guidance for implementing contour ridge system.
Key words:  Size distribution of soil aggregate loss  Enrich rate  characteristic indices of lost soil aggregate  Seepage  Rainfall intensity  Contour ridge system.