运用时域传输技术测定不同类型土壤的含水率

针对时域反射（TDR）技术测定含盐土壤、有机质质量分数高的土壤和红壤含水率过程中存在不适用的问题，该文应用一种基于时域传输（TDT）原理的水分测试仪，通过室内土柱试验，研究该仪器在不同类型的土壤上测定土壤含水率的适用性。研究结果表明：在风沙土、褐土和潮土3种类型的土壤上，土壤体积含水率和TDT输出的电压之间存在显著的线性关系，且可以用统一的线性关系计算土壤含水率，其估计标准误差是0.026 cm3·cm-3；在盐土（EC值为11.12 dS·m-1，含盐量为59.5 g·kg-1）上，土壤体积含水率和TDT输出电压值之间的线性关系仍然存在，其估计标准误差是0.025 cm3·cm-3；在栗钙土（有机质质量分数67.95 g·kg-1）和红壤上，土壤体积含水率和TDT输出的电压值之间的关系可以用三次多项式表示，校正关系式估计标准误差分别是0.028和0.015 cm3·cm-3。因此，基于TDT原理的水分测试仪能被广泛地应用于不同类型土壤的含水率测定，尤其在盐土、有机质质量分数高的土壤和红壤含水率的测定上表现出优于TDR技术的特点。

Measurement of soil water content for different soil types by using time domain transmission technology

According to the disadvantages of time domain reflectometry (TDR) on measuring water content for saline soils, high organic matter soils and red soils, a laboratory experiment was conducted to study the applicability of time domain transmission (TDT) instrument for measuring soil water content for different soil types. The results showed that there was a good linear relationship between soil volumetric water content and TDT voltage output for aeolian soils, cinnamon soils and fluvo-aquic soils. An uniform calibration relationship could be established for above soil types with a standard error of estimate of 0.026 cm3·cm-3; The linear relationship between soil volumetric water content and TDT voltage output was still hold for saline soils (EC value of 11.12 dS·m-1, salinity content of 59.5 g·kg-1) with a standard error of estimate of 0.025 cm3·cm-3; For chestnut soils (organic matter content of 67.95 g·kg-1) and red soils, the relationships between soil volumetric water contents and TDT voltage outputs were the cubic polynomials, with the standard errors of estimate of 0.028 cm3·cm-3 and 0.015 cm3·cm-3, respectively. Therefore, TDT instrument can be used to measure soil water content for many types of soils, and presents more superior performance for saline soils, high organic matter soils and red soils comparing with TDR.