利用TDR对不同盐分土壤水分含量的测定

Measurement of Soil Water Content in Different Soil Salt Contents Using Time Domain Reflectrometry(TDR)

通过室内模拟设定不同盐分含量土柱,比较TDR输出电压值和烘干法测定的水分含量值,探讨土壤盐分含量对TDR测定土壤水分含量的内在影响。结果表明:随着土壤中盐分含量的增加,TDR测定数值明显增大;土壤电导率(σ)<2.56dS/m时,TDR测定电压与烘干法测得水分含量显著正相关(r2>0.882);σ>3.2dS/m时,测定数值不能很好地反映土壤水分含量变化。比较TDR测定低盐条件下土壤水分含量发现,当土壤水分含量较大时,TDR测定相对误差较小,土壤水分含量较小时,TDR测定相对误差较大。根据分析结果构建TDR测定土壤水分的综合模型,结合大田验证,并对模拟值和实测值进行精度比较分析,表明该综合模型能够较好的模拟农田墒情状况。

In this paper soil water content was measured both by TDR（Time Domain Reflectometry） Output voltage value and by weighing method in many soil columns with different salt contents to ex plore the intrinsic influence of soil salt content to TDR measurements. The results showed that TDR measured moisture content values significantly increased with the increase of the soil salt content TDR measured voltage values and soil water content from weighing method showed a remarkable and positive correlation （r2〉0. 882） when soil content a〈2.56 dS/m, but the correlation was not high when soil content a〉3.2 dS/m. The results showed that the relative error of TDR measurements was smaller when soil water content was high; the relative error was larger when soil water content was low. Based on the analysis results the integrated model of soil moisture TDR measurement was build up. Combining the field validation with the simulated and observed values, the integrated model can better simulate soil moisture conditions.