Design of Soil Moisture Sensor based on Dual Frequency Signal Measurement

Abstract

The traditional soil moisture sensor is affected by soil temperature and soil polarization effect, and the measurement error of the traditional soil moisture sensor is large. To improve the measurement accuracy of soil moisture, this paper proposes a dual-frequency impedance-based soil moisture measurement method and designs a soil moisture sensor based on soil electrical conductivity. The design process solves three problems, which are the problem of polarization effect of soil, the problem of inaccuracy due to the interaction between the capacitance of the double electric layer and the capacitance between the wires, and the problem of temperature influence on the measurement results. Among them, the dielectric property method is based on the indirect measurement of soil dielectric property, and this method can achieve nondestructive and rapid measurement of soil moisture. The coupling problem of soil temperature and humidity is also analyzed and corrected. Experiments have proved that the accuracy of soil moisture measurement using this method is greatly improved compared with other sensors. It solves the high cost and waste of resources caused by inaccurate measurement accuracy of soil moisture sensors in the agricultural planting process