碎石的存在增加了土壤含水量测定的难度,为便于应用,一些学者将碎石当作细土或不透水介质处理,这在一些情况下可能产生很大误差。本文对忽略碎石或其含水量所引起的土石混合介质和细土含水量的误差进行了分析,并用室内实验验证了所得到的结果与相对误差的关系。结果表明,细土和土石混合介质含水量的相对误差与碎石含量以及碎石与细土含水量的比值有关。当碎石与细土含水量比值很大时,即便碎石含量很低也会产生很大误差;而当碎石与细土含水量比值很小时,高的碎石含量同样导致很大误差。此外,碎石与细土含水量的相对大小并非常数,而是随含水量变化的。因此,对土石混合介质田间水分状况的准确监测,以及水分和溶质迁移过程的定量模拟需要考虑碎石特性的影响。
Existence of rock fragments in soil makes it more difficult to measure water content of the soil. Some researchers take rock fragments as fine soil or impermeable media for the convenience of calculation, but this may lead to big errors in some situations. Analysis of these errors was conducted. Indoor experiments were carried out to validate the formula for calculating relative errors. Results indicate that the relative error in measuring water content of fine soil or soil-fragment mixture media was related to rock fragment content and ratio of water content of rock fragment to fine soil. When the ratio was high, big error may result even if the rock fragment content was low; and when the ratio was very low, high rock fragment content also induced great error. In addition, the ratio was not a constant, but varied with their water contents. Therefore, the hydraulic properties of rock fragments need considering in the study on monitoring accurately water regime and simulating quantitatively water and solute transport processes in fields of stony soil.