Alternate wetting and drying reduces aquifer withdrawal in mississippi rice production systems

Authors: ATWILL, R. LEE - Mississippi State University; KRUTZ, L.JASON - Mississippi State University; BOND, JASON A. - Mississippi State University; GOLDEN, BOBBY R. - Mississippi State University; SPENCER, G.DAVE - Mississippi State University; BRYANT, COREY J. - Mississippi State University; MILLS, BRIAN E. - Mississippi State University; GORE, JEFF - Mississippi State University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/4/2020
Publication Date: 11/9/2020
Citation: Atwill, R., Krutz, L., Bond, J., Golden, B., Spencer, G., Bryant, C., Mills, B., Gore, J. 2020. Alternate wetting and drying reduces aquifer withdrawal in mississippi rice production systems. Agronomy Journal. 112(6):5115-5124. https://doi.org/10.1002/agj2.20447.
DOI: https://doi.org/10.1002/agj2.20447

Interpretive Summary: This research was conducted to determine if alternate wetting and drying (AWD) irrigation in rice can reduce withdrawal from the Mississippi River Valley Alluvial Aquifer (MRVAA) without having an adverse effect on yield or profitability at the field-scale. Intermittent flooding decreased total water use while maintaining or improving rice grain yield and profitability relative to a traditional, continuous flood. Alternate wetting and drying is one of the most promising, current water-saving practices in midsouthern USA rice production. Potential barriers to adoption include a perceived negative effect of AWD on yield, profitability, nitrogen use efficiency, and weed control; however, this research demonstrates that properly managed AWD can improve the sustainability of the MRVAA while preserving or enhancing on-farm profitability.

Technical Abstract: Water level declines in the Mississippi River Valley Alluvial Aquifer (MRVAA) are attributed largely to withdrawals for rice (Oryza sativa L.) irrigation. This study was performed to determine if alternative irrigation strategies for rice could reduce withdrawal from the MRVAA without having an adverse effect on yield and profitability. Research was conducted at 19 on-farm locations across the Delta region of Mississippi from 2014 through 2016 to determine the effects of irrigation water management practice, i.e., conventional flood via cascade (CONV), multiple side inlet (MSI), and MSI coupled with alternate wetting and drying (AWD), on aquifer withdrawal, rough rice grain yield, irrigation water use efficiency (IWUE), and net returns above irrigation costs. Compared to CONV and MSI, up to 39% less water was applied to AWD (P ' .0001). Rice grain yield for AWD was not different from either CONV or MSI (P = .1343), despite substantial reductions in water use. Relative to standard irrigation strategies, AWD maintained or increased net returns up to $238 ha-1 for pumping depths from 5.5 m to 122 m and diesel prices from $0.42 L-1 to $0.98 L-1 (P = .0003). Irrigation water use efficiency was up to 59% greater for AWD relative to conventional systems due to the positive effects of the former on water use while maintaining yield (P = .0034). These data demonstrate that AWD can reduce withdrawal from the MRVAA while maintaining or improving yield and net returns relative to irrigation strategies currently employed across the midsouthern USA rice belt.