Field Evaluation of a Smartphone App for Scheduling Irrigation in Cotton

A smartphone app for scheduling irrigation on cotton in Georgia was released in early 2014.  The app is based on a crop-coefficient model and uses cotton crop coefficients developed by various research groups in the Southeast.  The app uses growing degree days and phenology as a trigger for changing the crop coefficient during the growing season.  The model uses a check-book approach to estimate when available soil moisture has been depleted by adding precipitation and irrigation to available soil moisture and subtracting FAO-56 ET adjusted by the crop coefficient from it.  The model was used to schedule irrigation at two locations in Georgia during the 2014 growing season.  Soil water tension was recorded continuously with a Watermark-based soil moisture sensing system at both locations.  This paper will describe the performance of the smartphone app during the drier than normal 2014 growing season and compare results to the wetter than normal 2013 growing season.