Surface Irrigation in the Lower Mississippi River Basin: Trends and Innovations

HighlightsBetween 1950 and 2017, there was a 12-fold increase in irrigated area in Arkansas and a doubling in Louisiana.Groundwater provides over 90% of the irrigation water applied to the 4 Mha of cropland in the LMRB.Ongoing efforts to address aquifer declines have been multi-faceted and include those of producers, public (local, state, and federal) institutions, and private organizations.Irrigation water management innovations include precision grading, reduced-flood or no-flood rice irrigation, pump automation, computerized hole selection, flowmeter requirements, and permit-based water use limitations.Abstract. The Lower Mississippi River Basin (LMRB) is an agricultural region of national and international significance. The basin relies heavily on the Mississippi River Valley alluvial aquifer to provide over 90% of the irrigation water applied to over four million hectares of cropland, with Arkansas using approximately 70% of the water and Mississippi and Missouri using approximately 15% each. Surface methods predominate, especially furrow irrigation using plastic lay-flat tubing in corn, cotton, peanut, and soybean and flood methods in rice. Irrigation extent has steadily increased by approximately 2% per year, such that irrigation withdrawals, combined with the region’s geology, have led to considerable aquifer declines in portions of Arkansas and Mississippi. Attempts to address these declines have been multi-faceted and include innovations in crop management and source water management, and programs in water resources management. Crop management innovations are focused on soybean and rice production and include precision grading, reduced-flood or no-flood rice irrigation, pump automation, and computerized hole selection. Adoption of these practices remains heavily reliant on field demonstrations and extension outreach. Source water management innovations include on-farm reservoirs, managed aquifer recharge, and regional-scale river diversions. Due to the concerted efforts of producers participating in regional and state programs, progress has been made in making surface irrigation more efficient and less reliant on groundwater. However, aquifer decline remains a challenge to the LMRB’s economy, ecology, and culture. Keywords: Aquifer decline, Irrigation, Lower Mississippi River Basin, Mississippi River Valley alluvial aquifer, Surface water.