TRIME-T3用于盐碱地土壤含水量测定的试验研究

以陕西省富平县卤泊滩盐碱地改良区为例，在其上游地段选取两块农田为研究对象，布置典型观测断面并埋设测管，运用TRIME-T3法和烘干法对观测断面土壤剖面含水量进行测定，并同步测定土壤含盐量。对两种方法测得的土壤含水量进行对比分析，研究土壤盐分对TRIME-T3法测定的土壤含水量影响以及该方法在盐碱地农田土壤剖面含水量测试中的应用。研究结果显示：（1）TRIME-T3法测量值较烘干法值偏大，但两者之间有较高的相关性，回归分析结果表明可以用y=0.866 3x+0.754 5的线性函数进行校正，校正后的TRIME-T3测量值中将有94.4%的值接近土壤含水量真实值。（2）通过对校正函数进行实例验证，结果表明TRIME-T3标定曲线值与烘干法测定值非常接近，绝对误差<1 cm³·cm^-3，相对误差在5%以下，表明TRIME-T3法通过一定的校正后可以很好地表达该盐碱地农田土壤剖面含水量信息。（3）通过对TRIME-T3测定的含水量与相应含盐量进行分析，发现两者之间的相关性并不显著，表明该方法可适用于盐碱地农田土壤剖面含水量测定。该研究结果可为类似地区盐碱地土壤剖面水分测定技术（TRIME-T3）的应用提供科学依据和理论参考。

Experimental study on measuring soil water content with TRIME-T3 in a saline environment

Time domain reflectometry (TDR)is a modern device for quick measurement of soil water content; it has been widely used for monitoring soil moisture status in farmland in recent years. But application of TDR in soils with high contents of salt or clay may result in large errors due to the embedded limitation of the instrument. Calibration is often needed on a site specific basis to improve the measurement accuracy. In order to examine the feasibility of using TDR for soil water content measurement in saline soil environment, the paper presented an experimental study in this paper to compare the differences in soil water contents measured by a TRIME-T3 TDR and the conventional oven-drying method. Soil sampling and onsite observations were conducted on a reclamation area with salinized soils in Shaanxi Province of China. Plastic access tubes of TDR were placed as groups in 2 strip fields; each group has 3 tubes spaced at 20 cm for easy access of the TDR. Of the total 6 monitoring points, manual readings of soil moisture at depth interval of 20 cm were conducted every 10 days; three readings were taken at each point and the averages were adopted as the final values. In the mean time, soil samples were taken for water content measurement with the oven drying method. The results show that soil water contents measured with TDR tended to be higher than those with the oven-drying method, the absolute deviation was in the range of 1-7 cm³·cm^-3, and the relative difference was between 2% and 25%, indicating the need for calibration process. The soil water content measured with the TRIME-T3 and the oven drying method were compared and fitted to a semi-empirical functional relationship, relatively good correlation was found between the two measurement results with R²=0.094 91, indicating that the TRIME-T3 measurements of soil water content were close to the field condition, and a simple linear relationship can be used for calibration. The electrical conductivity (EC)of the soil samples was not significantly correlated with the moisture content of the same soil profile. Further testing of the soil moisture correction function with TDR obtained a correlation coefficient of 0.99, showing promising application of the TDR technology for determining soil moisture in the study area.