A Smartphone App for Scheduling Irrigation in Cotton

A smartphone app for scheduling irrigation on cotton in Georgia was released prior to the 2014 growing season and is available on both the iOS and Android platforms.  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 as a trigger for changing the crop coefficient during the growing season but allows for user override based on observed phenology (first bloom, first open boll, etc.)  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 app has been tested by the University of Georgia and the University of Florida for two years and has performed well under a variety of growing conditions.  During 2014 and 2015 it was used to schedule irrigation in over 500 fields in southern Georgia and northern Florida.