基于驻波率原理的土壤含水率测量方法

Study on the Measurement of Soil Water Content Based on the Principle of Standing-wave Ratio

提出了一种基于驻波率原理的土壤含水率测量方法 ,介绍了其工作原理和使用范围 (主要分析土质对其测量结果的影响 ) ,并将其与目前广泛使用的 TDR及 FD两种测量方法进行性能对比 ,从而得出

As the development of precision irrigation, it becomes more important to measure soil water content rapidly, exactly and without destruction. Although the study on the measurement of soil water content has been carrying through for half a century, a satisfied means of measurement is still lack until now. A measurement of soil water content based on the principle of standing wave ratio (SWR) is introduced in this paper. Soil water content may be obtained by determining the dielectric properties of the soil. Soil can be considered in a physical sense as a three component mixture of air, solids and water. Generally, the dielectric constant of air equals 1, that of solids about 4, and that of pure water about 80, depending on temperature. It is obvious that the apparent dielectric constant ε (permittivity) of a soil is greatly influenced by the volumetric water content. So the measurement of soil dielectric constant is a critical to determine soil water content. According to the comparative measurements of soil water content among three different types of soil moisture sensors, SWR, FD (frequency domain) and TDR (time domain reflectometry) sensors, it demonstrated that SWR sensor was a measuring instrument with higher performance.