Experimental evaluation of low-cost resistive soil moisture sensors

Abstract

Soil moisture sensors are used mainly to help farmers to plan irrigation scheduling and save fresh water usage. The measurement of soil moisture based on electrical resistivity is widely used by farmers due to its simplicity and low cost. This research aims to evaluate the performance of low-cost resistive soil moisture sensors under greenhouse conditions. For this purpose, sensors have been assessed by several calibrations and evaluation experiments. Soil moisture percentages were logged daily to obtain curves relating moisture percentages to voltages provided by the sensors. The obtained results revealed that resistivity based sensors were affected by several sources of error, which lead to severe problems regarding accuracy and usability.