Evaluation of Hybrid Biodegradable Sensor Node for Monitoring Soil Moisture

Acquiring spatio-temporal soil moisture status at high spatial density within a farm field is the primary ingredient for precision water management. Contrary to conventional systems, this research seeks to develop a low-cost hybrid biodegradable sensor node that would allow the simple deployment of sensor nodes at a high spatial density. In the present work, low-cost ‘hybrid sensor nodes’ were developed, which comprise biodegradable and bioinert materials that were used in the sensor nodes for measuring soil water content, while the readout electronics were fabricated with conventional electrical circuit boards and Internet of Things (IoT) devices for wireless communication. Accuracy in detecting different irrigation treatments ranging from sufficient to severe deficit soil moisture conditions for maize plants was evaluated with the hybrid biodegradable sensor nodes. The time-series analysis of hybrid sensor readings in the greenhouse experiment indicated a good agreement between sensor readings and commercial TDR measurements at consecutive wetting and drying events in severe deficits to sufficient irrigation treatments. The statistical test, including ANOVA and Tukey’s HSD post hoc tests at p = 0.05 level of significance, also revealed significant differences among treatments in the mean values of soil moisture readings with hybrid sensors in most cases. Overall, the hybrid sensors could consistently detect soil moisture conditions at V4–V8, V9–V15, and V16–R2 growth stages of maize, making them useful for precision water management strategies throughout the crop season.