|King, Bradley - Brad|
Submitted to: National Irrigation Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2010
Publication Date: 12/5/2010
Citation: Evans, R.G., King, B.A. 2010. Site-Specific Sprinkler Irrigation in a Water Limited Future. National Irrigation Symposium. Phoenix, AZ. Dec 5-8. ASABE CDROM.
Technical Abstract: Available water supplies for irrigation are becoming more and more limited in the western USA and other locations around the world, and this trend is accelerating. This will force major changes to physical and managerial aspects as well as design of water delivery and on-farm irrigation systems. Thus, a water and energy limited future will be the likely catalyst that finally brings many of the existing precision agricultural technologies together for irrigated agriculture. Resource conservation as well as achieving environmental benefits under these conditions will probably require the adoption of non-uniform water applications, also known as site-specific irrigation. The goal of site-specific irrigation is to conserve water by directing the amount and frequency of water applications according to established spatial and temporal crop water requirements. However, twenty years of private and public research on site-specific irrigation has resulted in very limited commercial adoption of the technology. The primary reason for the very low rate of commercial adoption appears to be the absence of a market for the technology. Documented and proven water conservation strategies using site-specific irrigation are essentially nonexistent and its cost-effectiveness has not been demonstrated. Simulation studies comparing conventional and site-specific irrigation have reported water savings of 0 to 26%. Ironically for well-watered crop production, water savings from site-specific irrigation maybe greatest in humid climates by spatially maximizing utilization of growing season precipitation. In arid and semi-arid climates, the greatest potential water savings could come from highly managed deficit irrigation where spatial management of soil water deficit timing is used to maximize net return rather than yield. This strategy will require integration of irrigation system hardware, sensor systems, and decision support software, which will be challenging as significant knowledge gaps exist. It will also require a shift in production practices from maximizing yield to maximizing net return. Future research needs to focus on developing and documenting cost-effective site-specific water conservation strategies in order to develop markets for these irrigation technologies. The current status of site-specific sprinkler irrigation and some general barriers to adoption of the technology are reviewed. Keywords. Precision irrigation, precision agriculture, spatial variability, water management, irrigation controls, adaptive control systems, decision support, sensor systems.