Accounting for Temperature Effects on the Performance of Soil Moisture Sensors in Sandy Soils

Abstract

Core Ideas Two‐point α‐mixing model with modified α‐value improves ambient calibration for 5TM. Sensor's temperature response can be predicted as a function of water content. Linear trend is adequate for predicting sensor's temperature response. Capacitance sensors are widely used to monitor volumetric water content in both field and lab settings due to their low cost, ease of use, and capability of providing continuous measurements. However, these sensors are sensitive to temperature variations. Previous attempts to develop calibration equations that negate thermal effects incorporate many empirical constants that vary based on soil and sensor type. The purpose of this study is to examine the effects of temperature on sensor performance and develop an improved calibration equation for a widely used capacitance soil moisture/temperature sensor, the ECH2O 5TM. Small cell experiments were conducted with silica sands for a range of temperatures (20–50°C) and water contents. The 5TM showed a bi‐directional response to temperature increases based on the soil water content. Within the temperature range examined, the slope of sensor‐reading vs. temperature could be predicted using a linear relationship as a function of actual water content.