|SMITH, M.CADE - Mississippi State University|
Submitted to: Journal of Irrigation and Drainage Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/12/2018
Publication Date: 5/11/2018
Publication URL: https://handle.nal.usda.gov/10113/6472261
Citation: Massey, J., Smith, M.C., Vieira, D.A., Adviento-Borbe, A.A., Reba, M.L., Vories, E.D. 2018. Expected irrigation reductions using multiple-inlet rice irrigation under rainfall conditions in the lower Mississippi River Valley. Journal of Irrigation and Drainage Engineering. 144(7):04018016-1-04018016-13. https://doi.org/10.1061/(ASCE)IR.1943-4774.0001303.
Interpretive Summary: Rice is important to the economies of Arkansas and other rice-growing states in the Lower Mississippi River basin. Rice also relies heavily on groundwater pumped from the Mississippi River Valley alluvial aquifer which is declining in portions of Arkansas and Mississippi. Results from this study suggest that field-level management is more important to the amount of irrigation used to grow rice than the amount of rainfall received during the rice flood. Key to maximizing irrigation reductions when using multiple-inlet rice irrigation (MIRI) is to halt pumping once the field is full so that little, if any, water leaves the field. This can be accomplished using a simple flood depth gauge and pump control timer or other forms of automation. In future research, results from this study will be used to devise management practices that maximize rainfall capture that, in turn, could help alleviate on-going declines in the Mississippi River Valley Alluvial aquifer.
Technical Abstract: Multiple-inlet rice irrigation (MIRI) decreased irrigation applications by an average of 24% over an 86-day flood when compared to single-inlet (SI) rice flood distribution. Even in the absence of rainfall, MIRI required 22% less irrigation than SI when generalized water-balance equations were used to simulate irrigation use in a 16-ha, clay soil, straight-levee field typical of the Lower Mississippi River Valley (LMRV). The majority of MIRI savings was due to improved distribution uniformity that results in less runoff rather than increased rainfall capture. Using 260 site-years of rainfall from nine LMRV locations, these results also suggest that the wide variability in irrigation use observed in MIRI field trials is not due to variations in rainfall alone. Rather, other factors such as management style and field conditions likely impact irrigation use as much, if not more than, year-to-year variations in rainfall. Taken together, these results reinforce university extension efforts that educate farmers on the importance of irrigation management in realizing the water-conserving benefits of MIRI. Further, the results support efforts to automate irrigation monitoring and pump control by showing that significant irrigation savings occur with MIRI when pumping is halted in a timely manner.