Adoption of site-specific variable rate sprinkler irrigation systems

Abstract

More than 20 years of private and public research on site-specific variable rate sprinkler irrigation (SS-VRI) technology on self-propelled center pivot and linear move irrigation systems has resulted in limited commercial adoption of the technology. Competing patents, liability, and proprietary software have affected industry's willingness to move into a new technology area. Docu- mented and proven water conservation strategies using site- specific irrigation are quite limited. Marginal costs associ- ated with site-specific technologies are high. Although sales of SS-VRI are increasing, they are primarily being used for eliminating irrigation and chemigation on non-cropped areas of a field or for land application of liquid agricultural and municipal wastes. Various aspects of SS-VRI technol- ogies for general crop production are beginning to slowly gain widespread acceptance; however, their uses are largely focused on addressing symptoms of poor design and sub- optimal water and nutrient management. Although cur- rently underutilized, SS-VRI technology has the potential to positively impact crop water productivity, water and energy conservation, and the environment. There are also few economic incentives to motivate growers to move to higher levels of SS-VRI management. Greater adoption rates will likely require higher costs for water and energy, severely restricted water diversions on a broad scale, and enforce- ment of compliance with environmental and other regula- tions. Sustainable use of SS-VRI will require strong research support, which is currently limited. In the short term, adoption of SS-VRI technologies will be enhanced by addressing equipment deficiencies and research developing basic criteria and systems for defining management zones and locations of various sensor systems for both arid and humid regions. Training adequate personnel to help write site-specific variable rate irrigation prescriptions in humid and arid areas to assist growers with the decision-making process is also a high priority. There is also a large need to educate government boards and bankers on the potential benefits of these systems. The long-term challenges will be to demonstrate that SS-VRI will improve water manage- ment or increase net returns. There is a critical need to develop fully integrated management systems with sup- porting elements that accurately and inexpensively define dynamic management zones, sense within-field variability in real time, and then adaptively control site-specific vari- able rate water applications, which will be challenging as significant knowledge gaps exist.