We are developing a smart phone application that provides irrigation water management advice using satellite imagery, weather stations and field-scale farmer provided data.To provide tailored advice we use high resolution satellite imagery with national coverage provided by Google Earth Engine services to estimate field-specific crop growth information – crop coefficients – and we are among the first systems to do so. These coefficients combined with regional scale weather station data for major cotton growing regions and farmer-supplied data means we can run daily water balance calculations for every individual cotton field in Australia and provide irrigation decision support advice.We are using automated data processing to ensure the latest satellite and weather data is used for advice without manual effort.We will also deliver benchmarking data to farmers based on their previous seasons as well as peers’ farms in order to compare absolute (calculated) and relative (benchmarked) advice.