Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/2/2006
Publication Date: 12/20/2006
Citation: Massey, J.H., Smith, M.C., Johnson, A., Thomas, J., Tacker, P.L., Vories, E.D., Lancaster, S., Andrews, A.A., Ampim, P. 2006. Multiple-inlet plus intermittent rice irrigation increases rainfall capture and reduces non-point source runoff [abstract]. Proc. 31st Rich Technical Working Group, p.135 (CD-ROM)
Technical Abstract: Research was conducted in 2004 to determine the potential for water savings and reduced nonpoint source runoff using multiple-inlet irrigation plus intermittent flooding as compared to continuously flooded rice. Experiments were conducted at five farms ranging from the southern-most Mississippi Delta to the northeast corner of Arkansas. Each location consisted of two adjacent fields averaging 16 ha each. The two fields only differed in water management practice. The control field at each location was continuously flooded using the grower’s traditional practices. The experimental field used multiple-inlet irrigation plus intermittent flooding, whereby the flood was established at the appropriate time using 38-cm diameter plastic pipe to deliver water to each paddy simultaneously. After two weeks of continuous flooding, the experimental field was allowed to dry until about half of each paddy had exposed soil. At this point, the 8 to 10 cm flood was reestablished. This cycle was repeated every 5- to 9-days throughout the growing season. All water inputs and flood depths were recorded. Water samples were collected on a weekly basis for nutrient and pesticide analysis. Intermittent flooding did not affect pest pressure, plant-nutrient content, or rice yield. However, intermittently flooded rice used 56 cm water per ha compared to 81 cm per ha with continuously flooded rice, representing a 30% savings in irrigation inputs. This savings was due to increased rainfall-holding capacity, and reduced over-pumping and subsequent tailwater runoff. Based on 25-year historical rainfall data, our model predicts an average increase in rainfall capture of 67% and a 60% reduction in tailwater runoff for the intermittent flood as compared to the conventional flood system. Water samples are currently being analyzed for pesticide and nutrient concentrations and will be used to estimate surface water loadings from each irrigation treatment.