|STILES, MARK - Yazoo Mississippi Water Management District|
|EPTING, MARK - Yazoo Mississippi Water Management District|
|POWERS, SHANE - Yazoo Mississippi Water Management District|
|KELLY, DAVID - Yazoo Mississippi Water Management District|
|BOWLING, TAYLOR - Yazoo Mississippi Water Management District|
|JANES, LEIGHTON - Yazoo Mississippi Water Management District|
|PENNINGTON, DEAN - Yazoo Mississippi Water Management District|
Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2017
Publication Date: 5/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5750842
Citation: Massey, J., Stiles, M., Epting, M.C., Powers, S.R., Kelly, D.B., Bowling, T.H., Janes, L.C., Pennington, D.A. 2017. Long-term measurements of agronomic crop irrigation in the Mississippi Delta portion of the Lower Mississippi River Valley. Irrigation Science. 35(4):297-313. https://doi.org/10.1007/s00271-017-0543-y.
Interpretive Summary: Irrigation is necessary to maximize yields and economic profitabilities of corn, cotton, soybean, and rice grown in the Lower Mississippi River Valley. However, the primary source of irrigation in the region, the Mississippi River Valley alluvial aquifer, is declining. The irrigation use data produced by this study are necessary to perform detailed, accurate water budgets for the aquifer, and to determine long-term trends in irrigation use as a means to assess the effectiveness of irrigation conservation programs.
Technical Abstract: With over 4 million ha irrigated cropland, the Lower Mississippi River Valley (LMRV) is a highly productive agricultural region where irrigation practices are similar and the Mississippi River Valley alluvial aquifer (MRVA) is a primary source of on-demand irrigation. Owing to agricultural exports, the condition of the MRVA has national and international importance. The power conversion coefficient was used to measure season-long irrigation applied to cotton, maize, rice, and soybean grown in the Mississippi Delta portion of the LMRV over a 12-yr period that spanned a range of weather and cropping conditions. Averaged across all years and irrigation methods, irrigation rates were 9200, 3100, 2800, and 1800 m3 ha-1 for rice, maize, soybean, and cotton, respectively. Pivot and flood methods resulted in the lowest application rates when compared to furrow irrigation of row crops. In terms of rice, zero-grade fields received the least irrigation while multiple-inlet rice irrigation reduced irrigation by 19% relative to cascade flooding. No differences were measured between contour- and straight-levee rice fields. Irrigation rates for cotton and rice remained unchanged over time while maize-soybean rates increased by approximately 200 m3 ha-1 y-1. Except for cotton, irrigation rates correlated (r > 0.60) with total moisture deficit (rainfall minus pan evaporation). Study results provide irrigation rates necessary to calculate accurate, detailed water-budgets for the MRVA. The data may also serve as benchmarks for irrigation performance evaluations and to assess how conservation efforts might impact the aquifer.