The measurement of soil water content using the dielectric method

The accurate and fast real-time measurement of the soil water content plays an important significance in water policy and precision irrigation. The measurement method based on soil dielectric properties has been the most potential measurement method. However, many soil water sensors based on the dielectric properties are not accurate because of the influence soil texture or structure. How the electromagnetic frequency affected the soil dielectric properties was studied by selecting the different frequency in the different soil texture or structure. The results of experiment show that the soil texture or structure have great influence on the soil dielectric properties in the low-frequency or the medium frequency, however, it has almost unaffected on the soil dielectric properties in the high-frequency or the very high frequency. Therefore, according to the soil texture and selecting the optimal frequency, the accuracy of the soil water sensor is greatly improved.