荒漠草原不同土壤类型水分入渗特征

为了研究荒漠草原不同土壤类型对降水的响应过程,在宁夏盐池县皖记沟村选取分布较广的灰钙土、风沙土和基岩风化残积土为研究对象,采用双环法测定其入渗过程,分析并比较三者的入渗特征,利用模型拟合土壤入渗过程。结果表明:研究区内3种类型土壤入渗过程大致可分为3个阶段,0~5min入渗速率急剧下降阶段,5~10min入渗速率逐渐变缓并趋于稳定及30min后入渗速率达到相对稳定的状态。通过对不同土壤初始入渗速率、稳定入渗速率及60min累积入渗量对比分析,发现不同土壤类型的入渗特征存在差异,风沙土的入渗性能最好,基岩风化残积土次之,灰钙土入渗性能最差,原因是由于不同土壤结构的差异所导致。各土壤类型物理性质的差异性分析表明,土壤的机械组成和非毛管孔隙度是影响研究区土壤入渗的主要因素。利用4种土壤入渗模型拟合不同类型土壤的入渗过程,通用经验模型更适宜于描述研究区内土壤入渗速率随时间变化的情况。

Soil Infiltration Characteristics of Different Soils Types in Desert Steppe

In order to study the response process of different soil types in desert steppe to precipitation, the sierozem, aeolian sandy soil, and bedrock weathered residual soil were selected as the research objects in Wanjigou village, Yanchi country, Ningxia. The infiltration process was determined by double-ring sampling method, and the infiltration characteristics of the three were analyzed and compared. The models were used to fit the soil infiltration process. The results indicated that three types of soil infiltration process can be divided into three stages. The first stage was from 0 to 5 minutes, in which the infiltration rate decreased rapidly; during 5 min to 10 min, the infiltration rate brought a gradual decreased and tended to be stable, and reached a relatively stable state after 30 min. By comparing the initial infiltration rate, stable infiltration rate and cumulative infiltration rate of 60 minutes in different soils, it was found that the infiltration characteristics of different soil types were different. Soil infiltration of the aeolian sandy soil was the best, followed by bedrock weathered residual soil, while sierozem was the worst. The differences in soil infiltration characteristics were caused by the differences in soil structures. The analysis of the differences in soil physical properties showed that the mechanical composition and non-capillary porosity were the main factors affecting soil infiltration in the study area. Using four soil infiltration models to fit the infiltration process of different types of soil, the universal empirical model was more suitable for describing the change of soil infiltration rate with time in the study area.