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Seasonal variation in measured H(2)O and CO(2) flux of irrigated rice in the Mid-South

Reba, M. L., Counce, P. A.
Transactions of the ASABE 2016 v.59 no.1 pp. 199-206
Oryza sativa, carbon, carbon dioxide, crop production, data collection, developmental stages, diurnal variation, eddy covariance, energy balance, greenhouse gas emissions, greenhouse gases, irrigation, landscapes, methane production, plant growth, rice, seasonal variation, soil-plant-atmosphere interactions, water, water management, watersheds, Mississippi River, Southeastern United States
Rice (Oryza sativa) production in the lower Mississippi River basin constitutes over 75% of U.S. rice production, but little research has been done on water and carbon flux in this region at the field scale. Eddy covariance measurements of water and carbon dioxide (CO(2)) fluxes allow for integrated field measurement of the interaction between the landscape and the atmosphere. Measurements of these fluxes using eddy covariance were made in 2012 in a 60 ha rice (CL XL 745) field with typical production practices of the region. One hundred plants were monitored to track plant growth stage. Variability in measured fluxes was related to plant growth and production practices. Peak fluxes were measured during late vegetative stages. Corrected for energy balance closure, the maximum water flux was 6.05 mm d(-1) and occurred during later vegetative stages. Average water fluxes during late vegetative and early reproductive stages were approximately 4.45 mm d(-1). Diurnal variability in H(2)O and CO(2) flux peaked in early afternoon. Net CO(2) influx to the plant dominated the production season; hence, rice was a CO(2) sink. These findings begin to address the increased interest in understanding agricultural impact on net greenhouse gas (GHG) production and consumption. Future work might include similar data collection with the addition of methane flux from multiple fields where water management is varied to measure its impact on net GHG flux.