【作者】 郭伟；

【导师】 史志华；

【作者基本信息】 华中农业大学 ， 土壤学， 2007， 硕士

【摘要】 我国红壤丘陵区地处热带、亚热带，面积113万km²，水热资源丰富，是我国重要的农业生产区域。由于土地资源的不合理开发与利用，土壤侵蚀退化已成为本区农业生产的严重障碍。土壤团聚体是土壤结构的基本单元，其粒径分布及稳定性对土壤水分入渗和径流有重要影响，也与可蚀性密切相关。本文采用湿筛法和LeBissonnais法研究土壤团聚体稳定性，比较不同粒径和不同湿润速率团聚体稳定性，采用室内人工模拟降雨，研究了不同破碎机制下团聚体稳定性与坡面侵蚀过程的影响：通过对不同粒径的团聚体稳定性进行分析，研究不同粒径团聚体与坡面径流强度和产沙量之间的关系；不同湿润速率条件下土壤团聚体稳定性差异及坡面侵蚀过程响应；同时通过对侵蚀泥沙颗粒特性的分析，比较不同粒径与不同湿润速率下侵蚀泥沙粒径的区别。主要结论如下：（1）影响土壤团聚体稳定性的有土壤机械组成、粘粒含量、有机质等。研究结果表明，湿筛法QP2的稳定性最好，QP1的最差，QP3居中。LB法测定团聚体稳定性显示，不同粒径的团聚体差异显著，在前期含水量一致的条件下，随着团聚体粒径的增大其稳定性减小。不同湿润速率土壤团聚体稳定性差异显著，其排序为慢速湿润＞中速湿润＞快速湿润。（2）降雨过程中，不同粒径团聚体侵蚀过程差异显著，在前期含水量、坡度一致的条件下，随着团聚体粒径的增大，侵蚀量不断减小，供试3种土壤中＜2mm团聚体侵蚀量最大，依次为3.40、2.55和3.33gm^-2min^-1。不同湿润速率条件下坡面的侵蚀过程也存在显著差异，湿润速率越大，产流时间越慢，稳定径流强度越大。供试三种红壤QP1、QP2和QP3快速湿润时稳定径流强度比慢速湿润分别增加60％、37％和21％。同样，坡面侵蚀量也随着湿润速率的增大而增加，供试三种典型红壤在快速湿润条件下侵蚀量比中速湿润分别增加23％、28％和61％，比慢速湿润分别增加112％、85％和159％。在降雨侵蚀过程中，降雨和径流为这一过程提供能量，土壤是作用的对象。研究坡面侵蚀过程表明。随着径流强度的增大，产沙量呈增大的趋势，并且两者的相关性很好。（3）侵蚀过程中泥沙的颗粒分布状况与土壤团聚体的破碎情况和侵蚀能量密切相关，可以反映土壤表面结构变化以及径流携带搬运能力以及径流选择性搬运特性。实验中不同粒径团聚体侵蚀泥沙粒径差异显著，随着团聚体粒径的减小，侵蚀泥沙的平均重量直径逐渐增大。其中＜2mm团聚体的平均重量直径明显大于其它两种粒径，并达到显著差异，除了QP3外，2～3mm和3～5mm团聚体的平均重量直径没有显著差异。不同湿润速率的侵蚀泥沙平均重量直径（MWD）变化显著。其中湿润速率2mm h^-1的侵蚀泥沙平均重量直径最大，10mm h^-1的次之，60mm h^-1的最小。供试3种土壤慢速湿润的泥沙平均重量直径均与其它两种湿润速率差异显著。更多还原

【Abstract】 The red soil hilly region, located in the tropical and subtropical zones of Southeast China, consists of 9 provinces and 1 autonomous region. The area of region is about 1.13 million km~2, and hold 30% of the population. Because it has plentiful light, heat and water resources, the red soil hilly region has a high potential for agricultural and economic development. However, soil erosion and seasonal drought are major constraint for sustainable agriculture due to improper land use and uneven distribution of rainfall. Efficient rainfall use and erosion control, therefore, are very advantageous from eco-environmental and agricultural perspectives. Soil aggregate is a important part of soil and it’s stability has substantial effects on soil porosity and, therefore, may influence infiltration rate and runoff processes under rainfall. The objects of this study were to investigate the relationship between soil aggregate stability and soil erosion at hillslope. In this study, three red soils derived from Quaternary clay were studied. The main results as followed:(1) There was a significant interaction between soil properties and soil aggregate stability. The aggregate stability by wet sieve methods ranked in the order of QP2、QP3、QP1. By the Le Bissonnais’ method, the aggregate stability of different aggregate size and wetting rate is strongly different. As aggregate size increased, the aggregate stability decreased and the normalized mean weight diameter (NMWD) of different wetting rate is slow wetting, wet stirring, fast wetting.(2) There is a significant interaction between soil loss, runoff rate and aggregate size. The results showed that as clod size increased, the runoff rate decreased, ranging from 0.36 to 0.62mm min-1. The small aggregate size is likely to form a seal, consequently, the soil loss increased with decreasing aggregate size. There was also a significant interaction between soil loss, runoff rate and wetting rate. The results showed that as wetting rate increased, the runoff rate increased, ranging from 0.58 to 0.96 mm min-1. In each soil, thus, less soil loss was noted when exposed to slow wetting rate. A significant interaction between soil loss and runoff rate can be found. As the runoff rate increased, the soil loss increased too.(3)There is a significant interaction between sediment materials and aggregate size and wetting rate. During a rainfall, the largest MWD of sediment materials were found in aggregate size＜2mm of each soil. Wetting rate also played a great role in determining sediment materials. The largest MWD of sediment materials were found in fast wetting rate of each soil.更多还原