【作者】 孙站成；

【导师】 蔡崇法； 丁树文；

【作者基本信息】 华中农业大学 ， 土壤学， 2003， 硕士

【摘要】 本实验以鄂南几个侵蚀红壤为研究对象，运用人工模拟降雨方法，通过测量侵蚀参数与观测不同时段的表土微形态，力求找出降雨过程中红壤表土结构的变化过程及其与土壤侵蚀的关系，为我国南方水土流失提供理论依据。研究表明： 1．土壤侵蚀会引起土壤机械组成的改变。对于第四纪粘土发育的红壤，土壤质地粘重，而花岗岩红壤，侵蚀使其趋向砂质化。以微团聚体含量为基础计算的分散率，说明了六种供试土壤团聚体的稳定性，第四纪粘土红壤团聚体稳定，花岗岩红壤团聚体较易破坏。 2．降雨过程中的土壤微形态观测结合坡面产流过程分析，可认为土壤表面结构变化有产流前、产流到稳流、稳流三个阶段。这三个阶段表明了表土结构经历了有疏松到紧实，有不稳定到相对稳定的过程。 3．土壤溅蚀量是衡量土壤可蚀性的直接测定量之一。20min的溅蚀实验表明，T2、T3土壤溅蚀量较高，H3、T1土壤溅蚀率较低。从溅蚀率历时过程看，H1溅蚀率呈下降趋势，其余土样的溅蚀率在降雨初先升高，10min后下降。不同粒度团聚体的溅蚀实验表明，＜0.25mm的微团聚体，其溅蚀率历时曲线呈缓慢降低的态势；而＞0.25mm大团聚体，则是先升高再降低。在不同粒径的团聚体溅蚀率中，0.5～1mm的溅蚀率最大，溅蚀率最低的为2～3mm粒径的团聚体。在有无纱网两种处理条件下的产沙实验表明，雨滴溅蚀对坡面土壤侵蚀量有明显的影响，消除溅蚀作用后土壤侵蚀量不到有溅蚀作用的一半，说明溅蚀对坡面产沙的贡献占50％以上，不同土壤类型其贡献率不同，如结构性较差花岗岩红壤，溅蚀贡献率高达70％。 4．产流产沙实验表明供试土样H1、H2、H3、T1、T2、T3稳定径流量的大小关系为H1＞H2＞T3＞T2＞T1、H3，产流后1小时的平均产沙率的大小关系为T3、T2、H1＞H2＞H3、T1。在降雨过程中，H1、H2表土结构的变化有两个显著特征，一是团聚体容易破碎，二是表土迅速紧实。这两个特征导致H1、H2在产流开始后的12min内，产沙率迅速上升，随后H1产沙率缓慢波动下降，H2产沙率出现几个峰值。H3、T1表土良好的结构性和稳定的团聚体推迟和减缓了表土结构向紧实方向发展，使产沙率变化相对平缓，数值在较小的数值范围内变动。T3、T2团聚体发育差，缺乏多级孔隙，形成的高径流量和溅蚀率使T2、T3的产沙率在相对大的数值范围内变动。 5．利用IDRISI地理系统软件，对微形态照片进行处理，可以获得总空隙度。试用后，初步认为采用最大释然法分析总孔隙度可以获得结果，与容重法测的孔隙相比，结果偏小。更多还原

【Abstract】 The project was carried out to study the changes of topsoil surface structure and the relationship between soil surface structural change and the soil erosion under simulated rainfall, by measuring erosion parameter and observing soil surface micro morphology during the process of rainfall. The red several soils, such as H1 H2 H3 T1 T2 T3, were derived from three different parent materials in hubei province .We hope to provide the theory for the loss of soil and water in southern hill in China.1. The textures of H1,H2,H3,T1,T2,T3 were clay loam, silty clay loam, salty loam, sand clay, sandy loam soil, sand loam soil. Soil erosion would change soil mechanic composition. As for H2 and H3 derived from quaternary deposits, the textures of soils would become heavy because of soil erosion, whereas T2 and T3 of red soil of granite became sandification. The breakdown of soil aggregates was the premise of soil erosion, and dispersion ratio explained the stabilization of soil aggregates of six experimental soils, which was calculated by the content of micro-aggregates. The DR of H1,H2,H3,T1,T2,T3 were 0.84, 0.68, 0.58, 0.62, 0.87, 0.92, And the order was T3>T2>H1>T1 H2>H3.2. The photos of soil micro morphology explained the development of soil surface structure during the process of rainfall. The results showed that, there were three phases including the preceding of runoff, preceding of runoff to stability of runoff, stability of runoff. The three phases revealed the development of soil structure, which was the process from loosen to tighten, from unstability to stability.3. Soil splash erosion is one of the most important parameters of soil erosion. The results showed that, the amounts of T2 and T3 were highest, and the rates of soil splash erosion were lower during the rainfall of 20min. The curve of H1was descending, and the others soils were ascending during prophase of rainfall, descending after 10min. The results of different particle size aggregates showed that, the curve of splash erosion of aggregates of <0.25mm was slowly ascending during the rainfall process, whereas, according to >0.25mm, the curve was ascending during prophase of rainfall, then descending. According to aggregates of different particle sizes, the splash erosion rate of 0.5~lmm aggregates was highest, and 2~3mm was lowest. The effect of splash erosion on sloping surface erosion is evident. After the splash erosion was eliminated, the erosion amount was less than half of the amount when the splash erosion existed. It indicated the splash erosion contributed more than 50% erosion amount, but to the different soil type, the contribution ratio of erosionamount varied, such as the soils derived from granite, the contribution ratio reached 70%.4. The order of the amount of steady run-off was HI (6644ml) >H2 (6045ml) >T3 (4953ml)>T2 (4585ml)>Tl ( 3507 ml ) H3 (3155ml) , and the order of sediment wasT3[17.365 g#(m2#min)-1] , T2[16.305 g#(m2#rnin)-1] Hl[14.149 g#(m2#min)-1]>H2 [9.038 g#(m2#min)-1]>H3 [2.686 g#(m2#min)-1], T1 [2.139 g#(nr2#min)-1]. There were two typical characters in the soil surface of H1 and H2, which were breaking up of aggregates easily and sharply tightening of surface soil. The two characters sharply enhanced the rate of sediment, then H1 descending, and there were several peaks in the curve of H2. The fine structure and stable aggregates deferred the destroy of soil surface structure, and the change of sediment was slow. The stability of aggregates of T3, T2 was very low and multilevel pore was few, so soil splash erosion and sediment was very high.5. Porosity of micro image of H1, T2, H2 was analyzed by IDRISI Software. The results showed that the order of Porosity was H1<T2<H2, and Porosity sharply descended during 10min, then there was little change in the Porosity of soils with rainfall going on .更多还原