Measuring evapotranspiration and carbon dioxide fluxes in Mid-South US rice (Oryza Sativa) with eddy covariance

Abstract:

Rice (Oryza sativa), a staple crop for a large portion of the Earth’s population, is grown under flooded soil conditions. This results in greater water use than most other agricultural crops. Nearly 75% of US rice is grown the Mid-South states of the US. The objective of this study is to measure the evapotranspiration (ET) and carbon dioxide flux of conventionally flooded, commercial sized rice fields in this region. Measurements were made throughout the entire growing season during 2012, 2013, and 2014. The mean daily uptake of CO₂ emissions under flooded soil conditions was at 4.0 g m^-2 day^-1, four times greater during flood than post flood, while ET was measured during flood at 3.12 mm day^-1 was two times greater than post flood. Entire season measurements are important to characterize the micrometeorological conditions over agriculture fields. Future work will use eddy covariance to compare alternate irrigation methods on the net ecosystem exchange in commercial sized rice fields.