Variable Rate Irrigation System

Variable rate irrigation (VRI) for center pivots was developed by the University of Georgia Precision Agriculture Team. The technology is now widely offered by most pivot manufacturers. VRI allows pivots to vary the amount of water they apply along the length of the irrigation system to address the variability within fields. Although VRI is a great leap forward in improving water use efficiency, the system could be greatly enhanced by having real-time information on crop water needs to drive the application rates. So the Georgia Precision Agriculture Team developed the UGA Smart Sensor Array, which is an inexpensive wireless soil moisture sensing system that allows for a high density of smart soil moisture sensors – a feature needed to enable dynamic prescription maps. The smart sensors wirelessly transmit soil moisture data to a web server where the data are processed and converted to recommended irrigation application rates. These recommendations are converted into daily prescription maps which can be downloaded remotely to a VRI controller, creating a dynamic VRI control system. As a result, when an irrigation event is initiated, the VRI-enabled pivot applies water to meet actual soil moisture needs. During 2015, they conducted an experiment to assess the system in a 230-acre field in Calhoun County, Georgia. The dynamic variable rate irrigation control system performed well throughout the growing season. The VRI controls allowed the scientists to not irrigate non-farmed areas within the field, saving significant amounts of irrigation water. In addition, the control system allowed them to irrigate some areas off the field more frequently and other areas less frequently based on actual crop water needs. This system has the potential to greatly increase agricultural water use efficiency and how much crop farmers get for every drop of irrigation water applied. This technology may be a powerful tool for increasing agricultural productivity without increasing irrigation water demand.