黏粒质量分数对土壤水分蓄持能力影响的模拟试验

通过人工配制不同质地土壤,测定土壤水分特征参数,研究土壤中黏粒质量分数对其水分蓄持能力的定量影响。结果表明：1）黏粒质量分数对土壤水分蓄持能力有较大影响,土壤持水能力随黏粒质量分数增加而递增。2个水分特征曲线模型——Gardner模型及van Genuchten模型中,表征土壤持水能力的参数均随黏粒质量分数增加而增大。2）黏粒质量分数对土壤比水容量有较大影响,试验土壤在任一水吸力水平下的比水容量值均随其黏粒质量分数增大而增大。3）试验土壤饱和含水量、田间持水量分别与黏粒质量分数呈指数、对数正相关,凋萎系数与黏粒质量分数呈指数正相关。4）试验土壤有效水、迟效水含量随黏粒质量分数增加呈先升高后降低趋势,二者与黏粒质量分数均呈抛物线关系,最高点分别出现在黏粒质量分数为35.9%和35.8%处,易效水含量与黏粒质量分数相关性不显著。研究结果可为黄土区土壤水分蓄持机制进一步研究提供一定理论依据。

Effects of soil clay content on soil water holding capacity by simulated experiments

Quantitative effects of clay content on soil water-holding capacity were studied by compounding different texture of soil.The results showed that: 1) Soil clay content has a great effect on water-holding capacity.Soil water-holding capacity strengthened with the increase of clay content.The parameters of Gardner and van Genuchten soil water characteristic curve models went up with the increase of clay content.2) Soil clay content has a great effect on specific water capacity.The specific water capacity of experimental soils strengthened with the increase of clay content at any water suction level.3) The saturated water content and field capacity of experimental soils have exponential and logarithmic function relationship with clay content.And the relationship between the wilting coefficient and clay content is exponential function.4) while the clay content increase,available water and resistant available water content of experimental soils firstly increase and then decrease,and peak at the stage of soil clay content was 35.9% and 35.8%,respectively.There is no significant correlation between quickly available water and clay content.The results provides the theoretical basis for the further study on soil water-holding mechanism.