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土壤水分特征曲线描述土壤基质势ψ和含水量θ之间的函数关系,表征土壤的持水性能,是研究土壤水分入渗、蒸发、土壤侵蚀及溶质运移的关键。高寒气候特征使有机质在青藏高原地区大量积累,为确定多年冻土活动层土壤持水性能的影响因素,尤其是有机质的影响,在长江源北麓河地区采样分析。结果表明:相比于土壤粒度分布,容重和有机质是影响土壤持水性能的主要因素,其中高基质势下(0~-30kPa)以容重影响为主,低基质势下(-100~-1 500kPa)以有机质影响为主;有机质通过改变土壤结构和增强土壤的吸附性而影响土壤持水性能,同时影响程度取决于有机质的多少,土壤持水性与有机质含量呈正相关关系。本次研究有助于认识高寒地区土壤水文特征,对展开土壤水文过程的研究提供理论基础。
Soil water characteristic curve describes the relationship between soil matrix potential ψ and water content θ, and characterizes the water holding capacity of soil. It is the key to study soil water infiltration, evaporation, soil erosion and solute transport. Alpine climatic characteristics make the organic matter accumulate in the Qinghai-Tibet Plateau in large numbers. In order to determine the influencing factors of soil water holding capacity in the active layer of the permafrost, especially the influence of organic matter, sampling analysis is made in the Beiluhe area of the Yangtze River. The results showed that compared with the soil particle size distribution, bulk density and organic matter were the main factors influencing soil water holding capacity. Among them, the bulk density (0 ~ -30 kPa) was dominated by the bulk density. Under low substrate potential (-100 ~ -1 500kPa). Organic matter affected the soil water retention by changing the soil structure and soil adsorption. Meanwhile, the degree of influence depends on the amount of organic matter, and the soil water retention was positively correlated with the organic matter content. This study is helpful to understand the soil hydrological characteristics in the alpine region and provide a theoretical basis for the study on the soil hydrological process.