Lead Researcher: Derek Heeren
Contact: Derek Heeren 

Partners: University of Nebraska-Lincoln, USDA-ARS Bushland, TX, Valmont Industries

Abstract: The next step forward for advancing irrigation management, especially in the sub-humid eastern portion of the Great Plains, is increasing the adoption rates of scientific irrigation scheduling (SIS). Adoption rates of SIS for center pivot irrigation in the Great Plains would likely be much higher if SIS was automated and reliable. Field experiments will be carried out on a standard size (60 ha) center-pivot-irrigated field at the UNL Eastern Nebraska Research and Extension Center (ENREC) near Mead, NE. Treatments will include: IRT and Watermark (full irrigation), IRT and Watermark (deficit irrigation), ISSCADA System (IRTs and Acclima soil water sensors), Spatial Evapotranspiration Model, Common Practice, and Rainfed (no irrigation). Although one of the treatments in the field trials(ISSCADA) will be specific to Valmont Industries, the other research findings will be in the pre-competitive space and could be incorporated by other manufacturers and service providers, moving the industry toward center pivot automation.

Adoption rates of Scientific Irrigation Scheduling for center pivot irrigation in the Great Plains would be much higher if SIS was automated and reliable.

 1) Evaluate the accuracy of canopy temperature measurements from pivot-mounted sensors by comparing to stationary sensors and sensors deployed on unmanned aircraft 2) Develop a best management practice that could be automated for conventional irrigation and speed-control irrigation based on IRTs mounted on a center pivot and Watermark soil water sensors, and 3) Test and evaluate an existing patented system for SIS with pivot-mounted sensors (ISSCADA).

Planning, experimental design, and installation of equipment and supplies, including a new variable rate irrigation center pivot system, was successfully executed in 2020. Preliminary data analysis showed significant yield differences for the irrigation refill treatments (0% – rainfed, 50%, 100% (the depth recommended by the specific treatment), and 150%, with refill levels implemented by switching nozzles on the pivot lateral at the beginning of the season. The ISSCADA system was able to detect stress in the crop canopy. The threshold value for integrated Crop Water Stress Index (iCWSIse) for when to trigger irrigation needed to be adjusted from the default values, perhaps due to different climate factors compared to where ISSCADA was developed. This research will continue during the 2021 growing season.