Past, present and future of irrigation on the U.S. Great Plains

Authors: Evett, Steven - Steve; Colaizzi, Paul; LAMM, FREDDIE - Kansas State University; O`Shaughnessy, Susan; HEEREN, DEREK - University Of Nebraska; Trout, Thomas; KRANZ, WILLIAM - University Of Nebraska; LIN, XIAOMAO - Kansas State University

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2020
Publication Date: 7/21/2020
Publication URL: https://handle.nal.usda.gov/10113/7057958
Citation: Evett, S.R., Colaizzi, P.D., Lamm, F.R., O'Shaughnessy, S.A., Heeren, D.M., Trout, T.J., Kranz, W.L., Lin, X. 2020. Past, present and future of irrigation on the U.S. Great Plains. Transactions of the ASABE. 63(3):703-729. https://doi.org/10.13031/trans.13620.
DOI: https://doi.org/10.13031/trans.13620

Interpretive Summary: Historically, recognition of the High Plains aquifer as a source of plentiful irrigation water led to the development of millions of acres of irrigated production on the U.S. Great Plains, but declining aquifer levels threaten the future viability of irrigated agriculture in much of the Great Plains. To have a chance at glimpsing and affecting future circumstances, we must understand the past and the historical journey that has led to the present day. To provide direction to future research and policy, USDA ARS scientists and engineers at Bushland, Texas and Fort Collins, Colorado joined with university partners from Colorado, Kansas, Nebraska and Texas to analyze data on past, present and ongoing irrigated production, irrigation technology and practices. Irrigation was found to double the yields and water use efficiency (amount of yield per unit of water used in production) of both sorghum and winter wheat compared with dryland production. The increase is even greater for corn. Although aquifer declines have reduced irrigation water availability over much of the Great Plains, increasingly more efficient irrigation methods, such as low pressure precision application center pivots and subsurface drip irrigation systems, have allowed irrigated crop production to remain stable with much reduced water use. New technologies involving GPS guidance, and plant and soil sensing systems are shown to allow further reductions in water use while maintaining high yields because these systems provide for a carefully regulated deficit irrigation regime that reduces risk of crop failure. The sustainability of irrigated agriculture with reduced water supplies has been greatly increased due to advances in irrigation application and management methods resulting from combined state, federal, and private research and development efforts.

Technical Abstract: Motivated by the need for sustainable water management and technology for next-generation crop production, the future of irrigation on the United States Great Plains was examined through the lenses of past changes in water supply, historical changes in irrigated area and innovations in irrigation technology, management and agronomy. We analyzed the history of irrigated agriculture through the 1900s to the present day. We focused particularly on the efficiency and water productivity of irrigation systems (application efficiency, crop water productivity, and irrigation water use productivity) as a connection between water resource management and agricultural production. Technology innovations have greatly increased the efficiency of water application, the productivity of water use, and the agricultural productivity of the Great Plains. We also examined the changes in water stored in the High Plains aquifer, which is the region’s principle supply for irrigation water. Relative to other states, the aquifer has been less impacted in Nebraska, despite large increases in irrigated area. Greatly increased irrigation efficiency has played a role in this, but so also have regulations and the recharge to the aquifer from the Nebraska Sand Hills and from rivers crossing the state. The outlook for irrigation is less positive in western Kansas, eastern Colorado and the Panhandles of Oklahoma and Texas. The aquifer in these regions is recharged at rates much less than current pumping, and the aquifer is declining as a result. Improvements in irrigation technology and management plus changes in crops grown have made irrigation ever more efficient and allowed irrigation to continue. There is good reason to expect that future research and development on the part of federal and state researchers, extension specialists, and industry, often in concert, will continue to improve the efficiency and productivity of irrigated agriculture. Public policy changes will also play a role in regulating consumption and motivating on-farm efficiency improvements. Water supplies, while finite, will be stretched much further than projected by some who look only at past rates of consumption. Thus, irrigation will continue to be important economically for an extended period. Sustaining irrigation is crucial to sustained productivity of the Great Plains “breadbasket” because on average irrigation doubles the efficiency with which water is turned into crop yields compared with what can be attained in this region with precipitation alone. Lessons learned from the Great Plains are relevant to irrigation in semi-arid and sub-humid areas worldwide.