Design and evaluation of a capacitive sensor for real time monitoring of gravimetric moisture content in soil

Abstract

Soil moisture content measurements are required widely in the fields of lawn maintenance, irrigation systems of farming, soil processing in civil engineering etc. The paper presents a novel two terminal sensor for real-time volumetric soil moisture content measurement. The sensor was designed and tested with two terminals and an epoxy layer. This sensor was designed such that the range of the sensor in the range of the moisture measurement. An a-stable multi vibrator-based circuit was used to measure the capacitance across the two terminals when inserted into soil. A microcontroller-based system was used to measure, calculate the volumetric soil moisture content and save to a SD card. The results validate the effective applicability of the developed sensor in volumetric soil moisture content measurement.