A Soil Moisture Calibration Service for IoT-based Smart Irrigation

IoT plays a vital role in precision agriculture, enabling modern farm management technology to improve crop quality and quantity. Sensors can cover large farm areas, transmitting soil and weather data to an IoT Platform. For IoT smart irrigation, raw soil measurements generated in a physical quantity need to be converted into a percentage of soil moisture via a calibration process before usage. Most commercial soil moisture sensors transmit calibrated data using a generic calibration method, thus losing accuracy given that they do not consider the inter and intra-field variability. We developed an open-source application called SWAMP Kali, responsible for the online calibration of raw moisture data transmitted by soil probes. SWAMP Kali calibrates each data point according to a polynomial equation specific for each soil type. Our application is fully integrated into a smart irrigation platform (SWAMP) and one open-source IoT Platform (FIWARE). SWAMP Kali was deployed in a real smart agriculture scenario and calibrated more than 18,000 data points.