The First Application of Dynamic Variable Rate Irrigation to Cotton in Georgia: A Case Study

While technological innovation has substantially increased the efficiency of irrigated agriculture over the past several decades, significant potential exists for continued improvement. This paper will present a case study of the first application of the dynamic variable rate irrigation (VRI) system developed by the University of Georgia. The system consists of the EZZone management zone software, the University of Georgia Smart Sensor Array (UGA SSA) and an irrigation scheduling decision support tool. An experiment was conducted in 2017 to evaluate the irrigation efficiency of the system in cotton. The field divided into four parallel strips. All four strips were 788 ft wide. Every other strip was designed to receive variable rates based on the UGA SSA decision support tool (DST) and at the rest of them uniform irrigation based on the farmer’s recommendations. Continuously, Sentinel-2 satellite images from the last two years were analyzed to find the NDVI (Normalized Difference Vegetation Index) and NDWI (Normalized Difference Water Index) variability of the field. Additionally soil electrical conductivity data, soil type data as well as elevation data were combined in the EZZone software to delineate management zones. The recommended management zones were used only at the strips where irrigation was applied with variable rates. Eighteen UGA SSA soil moisture probes were installed in the 4 strips after planting. The UGA SSA system reported soil moisture data hourly and they were visualized on the UGA SSA web portal. The DST converted soil moisture data to actionable irrigation recommendations based on the latest soil moisture readings. This paper will present the results of the yield and irrigation water use efficiency comparison between the two irrigation treatments. A preliminary analysis of the data showed that the irrigation water use efficiency was 30% higher in the VRI strips than the strips irrigated uniformly.