Location: Soil, Water & Air Resources ResearchTitle: Seasonal carbon and water dynamics in corn-soybean rotation systems in Central Iowa Author
|Dold, Christian - Orise Fellow|
|Moorman, Thomas - Tom|
|Sauer, Thomas - Tom|
|Drewry, Darren - Jet Propulsion Laboratory|
Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2018
Publication Date: 12/18/2018
Citation: Dold, C., Hatfield, J.L., Prueger, J.H., Moorman, T.B., Sauer, T.J., Drewry, D.T. 2018. Seasonal carbon and water dynamics in corn-soybean rotation systems in Central Iowa [abstract]. In: Preceedings of the American Geophysical Union Fall Meeting, December 10-14, 2018, Washington, DC.
Technical Abstract: The Midwestern US is one of the most important regions for rainfed corn [Zea mays L.] and soybean [Glycine max (L.) Merr.] production worldwide with approximately 90% of the agricultural land in this region being cultivated with these two crops. Carbon and water dynamics in Midwestern cropland are therefore mostly driven by corn and soybean production. These carbon and water fluxes may change both temporally as well as spatially, even on a regional level, owing to micro-climate and crop management. The aim of this study was to analyze seasonal changes in carbon and water fluxes in corn-soybean rotation systems on a regional scale in Central Iowa in 2016. Eight eddy-covariance stations recorded carbon and water fluxes in four pairs of fields with annual corn (n=4) and soybean (n=4) rotation during the growing season (day 145 – 269). Daily and seasonal evapotranspiration (ET) and net ecosystem production (NEP) were calculated, and NEP partitioned into gross primary production (GPP) and ecosystem respiration (Re). The inherent water use efficiency (IWUE*) was calculated as GPP multiplied by the ratio of vapor pressure deficit and ET. Daily ET increased with maximum air temperature until >33 degrees C and decreased thereafter, while IWUE*, NEP, and GPP decreased at >30 degrees C in both crops. Daily NEP, GPP, and IWUE* also decreased with increasing rainfall and soil water content. Seasonal (x¯ ± SE) NEP, GPP, and Re were 678 ± 63, 1483 ± 100, and -805 ± 40 g C m-2 for corn, and 263 ± 40, 811 ± 53, and -548 ± 14 g C m-2 for soybean, respectively. Seasonal values of ET were 371 ± 5 and 381 ± 22 mm, while IWUE* 39.1 ± 2.4 and 19.4 ± 0.8 for corn and soybean, respectively. While carbon and water fluxes changed substantially between crops, the differences among sites were insignificant despite differences in crop management. These findings are important to validate remote sensing of carbon and water fluxes on field and regional level, and model optimum crop growth conditions.