Analysis of Yield Response with Deficit Drip Irrigation Strategies, Remote Sensing with UAVs, and Thermal Image Processing

Abstract.

The study was conducted at University of Maryland Eastern Shore farm to investigate the impact of a variety of deficit irrigation strategies in the 2015 and 2016 growing seasons on corn production. Deficit irrigation is being widely investigated as a valuable and a sustainable production strategy. The objectives of this study were to identify highly efficient deficit irrigation strategies; to calculate and analyze Crop Water Stress Index (CWSI) and Irrigation Water- Use Efficiency (IWUE), and to process raw thermal images captured via UAV into stitched images. For this study, the growing season was divided in three equal portions corresponding to early, middle, and late stages of crop growth, approximately 35 days each. Two deficit irrigation treatments (0-30-15) and (0-50-50) were chosen in 2015 and treatment (15-50-0) was added in 2016. During both 2015 and 2016 growing seasons, a non-irrigated (0-0-0) control area (rain-fed), and a traditionally irrigated (70-70-70) control area were also included; 70 corresponds to maintaining 70% Plant Available Water (PAW) in the soil at all times. PAW corresponds to a particular soil moisture percentage for specific soils. Soil moisture was monitored and irrigation applied when soil moisture dropped below these known thresholds. The results of this field study indicated that deficit irrigation made judicious use of irrigation water. The ability to capture images via UAV, followed by assembling, mosaicking, and processing to display a CWSI image of an entire field was demonstrated. The UAV-based thermal imagery holds promise in crop health assessment in water stressed conditions.