In Situ Profiling of Soil Water Content

Measuring the soil moisture is an essential task in precision agriculture and smart irrigation strategies. However, most of the available measurement instruments are expensive and are not suitable for use by traditional farmers with a low level of education. In addition, several technical limitations affect the performance of the currently used soil moisture sensors, such as weather changes, dependency on calibration, soil types, aging and drift among others. This policy brief is based on the work done on implementing a new low-cost and simple-to-use instrument, for measuring the soil water content, based on a discrete capacitive sensing technique. The proposed device measures the vertical soil moisture profile and serves as an indicator for water infiltration rate. In contrast to the existing commercial capacitive sensors that measure volumetric water content, the proposed sensor is measuring the soil moisture at different depths. The presented device is capable of long-term field operation, and is characterized by: 1) low-cost and simple-to-use, 2) robust sensing technique (does not require calibration against different soil types), 3) protection against corrosion and reduced aging, and 4) low-power consumption allowing long-term field deployment.