中文摘要：

耕作土壤在降雨、灌溉之后，其由翻耕后的疏松状态逐渐变得较为紧实，土粒之间会重新结合，土壤结构得到重组。土壤抗侵蚀能力发生了一定变化。通过土盒模拟土壤干湿交替过程，研究耕作土壤干湿交替过程中土壤容重和静水崩解变化。采用Richards模型对土壤崩解过程进行了模拟，分析干湿交替对土壤崩解速度的影响．结果表明：随土壤干湿交替次数的增加，土壤容重增长缓慢，土壤的固结从快变慢。随干湿交替次数的增加，土壤崩解速度逐渐降低。其崩解过程可划分为缓慢崩解阶段、指数崩解阶段和崩解完成阶段。随干湿交替次数的增加，缓慢崩解阶段延长，指数崩解阶段推迟出现。经3次干湿交替后，土壤崩解速度显著降低，土壤抗蚀性增强。

英文摘要：

Irrigation and rainfall would make tilled loss soil relatively compact because water makes soil particles cohered to each other, altering the soil structure and erosion resistance. Soil disintegration rate is regarded as a key parameter to evaluating soil＇s erodibility. Accurate prediction of disintegration rate of tilled soil is very important to effective management and conservation of soil and water. In this paper, simulation of wet-dry alternation of soil was performed using a soil box to explore effects of the alternation on soil bulk density and soil hydrostatic disintegration rate, and the effect was simulated with the Richards model. Soil wetting process was simulated by immersing the soil in slack water and soil drying process was by oven-drying. The two processes went one after the other forming a round of wet-dry alternation. After the alternation, the soil gradually concreted. Based on soil concretion settling rate and quantity of the soil sample, soil bulk density was calculated. At the same time soil samples were collected with a square ring sampler for determination of soil disintegration rate using the hydrostatic disintegrating method. The soil samples used in the experiment were collected from the topsoil layer of a farmland in Yangling and silt loam in soil texture. The of the growth process. However, the cumulative soil disintegration process presents a typical S-curve, so the Richards model can be used to simulate the soil disintegration process and to analyze effect of wet-dry alternation on soil disintegration rate. The paper has come mainly to the following conclusions： With the wet- dry alternation increasing in frequency, bulk density of the soil gradually becomes heavy, but concretion slows down, and disintegration rate declines steadily. The Richards equation can be used to better describe the process of soil disintegration. Based on the characteristic points of soil disintegration displayed in the model, soil disintegration process can be accurately divided into three phases： sl