前期土壤含水率对红壤团聚体稳定性及溅蚀的影响
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国家自然科学基金资助项目(40930529)。


Effect of antecedent soil moisture on aggregate stability and splash erosion of krasnozem
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    摘要:

    为了探究前期含水率对南方红壤团聚体稳定性及溅蚀的影响,选取泥质页岩和第四纪红黏土发育的4个典型红壤为研究对象,就5个前期含水率(3%、5%、10%、15%、20%)条件下3~5 mm团聚体水稳定性特征及其与溅蚀的关系进行了初步的探讨。结果表明,消散作用是团聚体破碎最有效的机制,土壤前期含水率越大,团聚体破碎程度越小。随着前期含水率的升高,泥质页岩发育的2种红壤水稳性团聚体平均质量直径(MWDwa)显著增大;第四纪红黏土发育的2种红壤水稳性团聚体平均质量直径(MWDwa)先增大后减小,拐点出现在含水率为15%条件下。泥质页岩发育2种红壤溅蚀量随前期含水率的升高显著减小;第四纪红黏土发育2种红壤溅蚀量随前期含水率的升高呈现先减小后增大的趋势,在含水率为15%时达到最小。团聚体水稳性较高的土样,溅蚀粒径分布呈双峰曲线分布,主要分布1~0.5和<0.05 mm范围内,且前期含水率越高,<0.05 mm溅蚀颗粒含量越大;而团聚体水稳定性较差的土样,除前期含水率为20 %外,溅蚀粒径分布呈单峰曲线分布,主要分布在0.25~1mm。该结果为红壤区农业水土工程及机侵蚀机理研究提供一定的参考,对完善坡面水蚀模型具有一定的参考价值。

    Abstract:

    Abstract: Rainfall splash erosion, usually the first step in soil loss and sediment transport, is a critical process in hillslope water erosion. It is recognized that antecedent moisture content influences the re-aggregation of soil particles and their subsequent enhanced ability to resist exogenic soil erosional forces. The purpose of this study was to determine the effect of antecedent moisture on aggregate stability and splash for Utisols in subtropical China. Four soil samples derived from Shale and Quaternary red soil and five antecedent moisture contents (3 %, 5 %, 10 %, 15 %, and 20 %) were tested in this study. Effects of antecedent moisture on aggregate stability and splash erosion were discussed based on the analysis of aggregate water stability using wet-sieving method and rainfall simulation with an intensity of 60 mm/h for 45 minutes in laboratory. Mean weight diameter of aggregate water stability (MWDwa) was used as the aggregate stability index. The fragments splashed out were measured by wet sieving with sieves of 2.0 mm, 1.0 mm, 0.5 mm, 0.25 mm, respectively. And fragments less than 0.25 mm in size were then measured by a laser diffraction sizer in five classes (0.2-0.25 mm, 0.15-0.2 mm, 0.10-0.15 mm, 0.05-0.10 mm, and < 0.05 mm). The results showed that aggregate water stability significantly increased with increasing antecedent moisture content and slaking was the most efficient breakdown mechanism. With the increase of antecedent moisture content, MWDwa values of the soils derived from Shale significantly increased. However, the MWDwa values of soils derived from Quaternary red clay increased initially then decreased, with the most stable value at the moisture of 15%. With antecedent moisture content increasing, the total mass of splash for soils derived from Shale decreased, but decreased first then increased for soils derived from Quaternary red clay, with a minimum value at the moisture of 15%. The size-selectivity was determined by the size distribution and surface structure at different antecedent moisture contents. For more stable soils, size distribution of the splashed fragments is bimodal with a major peak at 1-0.5 mm and < 0.05 mm. For less stable soils, size distribution of splashed is unimodal with a large peak at 1-0.25 mm except the ones at the moisture of 20 %. The results can provide a reference for agricultural water-soil engineering and water erosion mechanisms of Utisols, which has great significance for improving soil erosion models.

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马仁明,蔡崇法,李朝霞,王军光,冯君园,吴新亮,朱惠荣.前期土壤含水率对红壤团聚体稳定性及溅蚀的影响[J].农业工程学报,2014,30(3):95-103. DOI:10.3969/j. issn.1002-6819.2014.03.013

Ma Renming, Cai Chongfa, Li Zhaoxia, Wang Junguang, Feng Junyuan, Wu Xinliang, Zhu Huirong. Effect of antecedent soil moisture on aggregate stability and splash erosion of krasnozem[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE),2014,30(3):95-103. DOI:10.3969/j. issn.1002-6819.2014.03.013

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  • 收稿日期:2013-07-24
  • 最后修改日期:2014-01-05
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  • 在线发布日期: 2014-01-13
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