红壤坡面土壤团聚体特性与侵蚀泥沙的相关性

Abstract

PDF HTML阅读 XML下载 导出引用 引用提醒 红壤坡面土壤团聚体特性与侵蚀泥沙的相关性 DOI: 10.5846/stxb201611112299 作者: 作者单位: 浙江大学环境与资源学院,浙江大学环境与资源学院,浙江大学环境与资源学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41471221） The relationship between soil aggregates and eroded sediments from sloping vegetated red soils of South China Author: Affiliation: College of Environmental and Resource Sciences,Zhejiang University,Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment,College of Environmental and Resource Sciences,Zhejiang University,Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment,College of Environmental and Resource Sciences,Zhejiang University,Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment Fund Project: National Natural Science Foundation of China [grant number 41471221] 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:借助室内人工模拟降雨试验为研究手段，以强降雨过程中红壤丘陵区坡菜地侵蚀泥沙颗粒组成及土壤团聚体稳定性变化特征与规律为研究目的，分别在不同坡长（2，3，4m）、不同植被覆盖度（0，30%，60%，90%）条件下进行了有效模拟降雨试验共计12场次，每场次降雨试验的产流历时设计为30min，固定雨强为2.0mm/min。试验结果表明：1）侵蚀泥沙中颗粒粒径以 < 2μm粘粒和2-20μm细粉粒为主。在原土中，粘粒（0-2μm）和细粉粒（2-20μm）含量之和占总量的43.92%，在泥沙中粘粒和细粉粒之和占总量的约57.08%，均出现不同程度的增加；2）在不同处理中，坡面土壤 > 1mm干筛法团聚体含量明显大于湿筛团聚体（ > 1mm）的含量，可认为水稳性团聚体的含量更能作为衡量土壤结构的稳定性的指标。 > 0.25mm团聚体分散度（PAD0.25）和 > 2mm团聚体分散度（PAD2）含量均出现增大，而 > 0.25mm水稳性团聚体含量（WAS0.25）减少，植被覆盖度对土壤团聚体稳定性影响明显强于坡长；3）WAS0.25含量是影响侵蚀泥沙的颗粒粒径分布的主要因素，随着坡面土壤中WAS0.25的增加，侵蚀泥沙的平均重量直径逐渐降低。同时，泥沙颗粒平均直径与土壤团聚体平均重量直径（MWD团聚体）含量呈极显著负相关，可知坡面大团聚体越稳定，坡面土壤的粗化过程越不易形成。 Abstract:Soil erosion is a serious problem that has significant environmental impacts, including declines in soil quality, sedimentation of reservoirs, and nonpoint source water pollution. Thus, it is important to study soil erodibility and mechanisms for nutrient loss on sloping land. Plenty of studies have researched soil erosion factors, such as land use patterns, plant cover type and ratio, slope length and gradient, rainfall intensity and amount, and raindrop kinetic energy; these studies have been key to characterizing these processes. It is generally recognized that plant cover and slope length have a significant impact on soil erosion and nutrient loss. However, these parameters have often been studied in isolation, and few have researched the combined effects of sedimentation and nutrient loss. In this study, we analyzed the effects of slope length and plant cover ratio on the particle size distributions (PSDs) of soil and eroded sediments from sloping vegetated fields under heavy rainfall. We evaluated the change in soil aggregate stability characteristics to explain the relationship between PSDs of the eroded sediment and soil aggregate stability. Twelve simulated rainfall experiments were conducted in a glasshouse with a rainfall intensity of 2mm/min and runoff was produced within 30min. For this study, we implemented three slope lengths, 2, 3, and 4m, and four levels of vegetation cover ratios, 0, 30%, 60%, and 90%, in 2014 and 2015. The micropipette method was used for particle size analysis of soils and eroded sediments. Surface soil samples before and after rainfall were separated into five soil aggregate sizes, > 2mm, 1-2 mm, 0.5-1mm, 0.25-0.5mm, and < 0.25mm, by dry sieving and wet sieving. The experimental indexes to evaluate soil aggregate stability included water stable aggregates (WSA), mean weight diameter (MWD), and dispersion degree of soil aggregate (PAD). The results showed that clay particles ( < 2μm) and fine silt particles (2-20μm) were the main size fractions in eroded sediments. Surface runoff, which causes soil erosion, is a selective transport process; hence, there were more clay particles and fine silt particles in the eroded sediments (approximately 57.08%) than in the original soils (43.92%). The proportion of clay particles in the eroded sediment increased slightly as the vegetation cover ratio increased. There were no significant differences in PSDs of eroded sediments for different slope lengths with the same cover ratio (P > 0.05). The content of > 2mm and > 0.25mm PAD (PAD0.25, PAD2) increased, whereas the content of > 0.25mm WSA (WSA0.25) decreased after rainfall. Vegetation cover ratio had a more significant effect on > 0.25mm soil aggregate stability than did slope length. We found that the WSA index generally reflected the difference in soil structure stability. WSA0.25 was the main factor affecting PSDs of eroded sediments; the MWD content of the eroded sediments decreased gradually whereas WSA0.25 content increased. We also found a significant negative correlation between PSDs of eroded sediment and MWD of soil aggregate. Finally, we observed that more stable soil macro-aggregates resulted in less coarse soil surfaces. 参考文献 相似文献 引证文献