滴灌棉田粉砂壤土的水分特征曲线试验研究

摘要

为探究滴灌棉田粉砂壤土土层深度对土壤水分特征曲线的影响,采用张力计法对0～20 cm,20～40 cm,40～60 cm深度土层土壤水分特征曲线测定并分析,选用van Genuchten模型进行拟合.结果表明,随着土层深度的增加,土壤体积含水率随土壤水吸力的变幅降低,变化最快的土层为0～20 cm,20～40 cm;在同一吸力下,土壤容重越大的土层,相应含水率越大,各土层含水率大小表现为:0～20 cm>20～40 cm>40～60 cm;不同土层吸湿曲线与脱湿曲线不相同,有滞后现象存在.试验区各土层吸湿与脱湿土壤水分特征曲线均与van Genuchten模型拟合较好,其中40～60 cm土层拟合最优,拟合相关系数0.8600～0.9949,实测值与模拟值均方根误差均小于0.01.%In order to explore the effect of soil depth on soil water retention curve,the soil water retention curve of 0-20 cm,20 -40 cm and 40 - 60 cm soil layers were measured and analyzed by tension meter method,and van Genuchten model was used to simulate and analyze.The results showed that with the in-crease of soil depth,the volumetric water content of soil decreased with the soil water suction amplitude and the fastest changing soil layer was the soil at 0-20 cm,20-40 cm.Under the same suction,the greater the soil bulk density,the greater the corresponding water content.The size of soil moisture content showed:0-20 cm>20-40 cm>40-60 cm.The moisture absorption curves of different soil layers were different from the desorption curves and there was hysteresis in the process.The soil moisture retention curve of the soils in the test area were well fitted with the van Genuchten model,and the best result ap-peared at 40-60 cm layer.In addition,the correlation coefficient was between 0.8600 and 0.9949,and the root mean square error of the measured and simulated values was less than 0.01.