测量土壤质量含水率的体积置换方法

Direct Measurement Method of Soil Moisture by Volume Replacement

提出了一种直接测量土壤质量含水率的方法，达到传统干燥称重法同等的效果。该方法将任意待测土样置于已知体积的容器中并将容器注满水，由已经测量得到的湿润土壤的质量、容器中盛满水后土样与水的总质量、假设已知的土壤颗粒密度和水密度，计算得到土壤质量含水率。给出了相应的测量方法、测量过程、土壤含水率计算过程。采用4种土壤，配制成10％、15％、20％、25％、30％的初始土壤体积含水率。用提出的体积置换法测得土壤质量含水率后，再将土样干燥，得到传统干燥法测量的土壤质量含水率。将两种方法测量的结果进行比较，说明所提方法的可行性。结果表明提出的方法较传统干燥8h后称质量法测量的含水率高2．4％-2．7％。而传统方法延长干燥时间后，测量得到的含水率约增加1％～3％。表明所提方法测量过程优于传统方法。

This article presented a method for direct measurement of soil moisture, which was equivalent to the conventional oven-dry method. Under assumed soil particle density, soil samples for measurement were placed into a container of known volume, and then the container was filled with water to saturated. The weights before and after saturation of the soil sample, the assumed soil particle density and water density, were used to estimate the original soil moisture content. The measurement method, procedures as well as the computational method and procedures were detailed. Four soils were used for the validation experiments, under five initial soil water contents 10% , 15% , 20% , 25% and 30%. The measured results were compared with those measured by the oven-dry method. The data showed that the measured moisture contents by the new method were about 2.4% - 2.7% higher than those by the traditional method after oven-dry for 8 h. Extended oven-dry for 12 to 48 h produced 1% -3% higher water content than dried for 8 h. The proposed method performs better than the conventional method. The results indicate the feasibility of the new method.