Improved Agricultural Irrigation Scheduling Using a Soil Water Content Sensor - Case Study

Abstract
The key to scheduling irrigation timing and amounts is determining moisture depletion in the soil. Two common methods include tracking crop evapotranspiration (ETc) and tracking the water content with a sensor buried in the soil. In Colorado, a popular online tool that estimates the ETc for a variety of well-irrigated crops is the Colorado Agricultural Meteorological Network (CoAgMet). However, the use of CoAgMet to estimate the ETc of a water-stressed crop is limited. Therefore, this study analyzed the capability of a digitized Time Domain Transmissometry (TDT) soil water content sensor (Acclima, Inc., Meridian, ID) to schedule irrigation timing and amounts of a fully-irrigated and a water-stressed maize crop in eastern Colorado. According to the results, it was concluded that the TDT sensor can reliably be used to monitor soil water use and thus help reduce pumping costs, while ensuring that the soil moisture remains within the Management Allowed Deficit (MAD).