Canopy Chamber Measurements of Carbon Dioxide Fluxes in Corn and Soybean Fields
2018
Wang, Zhuangji | Luo, Chenyi | Sauer, Thomas J. | Helmers, Matthew J. | Xu, Liukang | Horton, Robert
CORE IDEAS: Canopy chambers were used to measure CO₂ exchange rates (CER) in corn and soybean plots. Daytime and cumulative CER fluxes were calculated from measured instantaneous CER fluxes. Chamber CER fluxes were consistent with eddy covariance flux tower CER fluxes. Crop canopy CO₂ exchange rate (CER) includes crop photosynthesis and soil/plant respiration. A portable canopy chamber is effective in determining crop CER values at a relatively small spatial (m²) scale. The objectives of this study were to use a canopy chamber to measure CO₂ fluxes in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. Chamber measurements were performed for 18 and 15 d in 2013 and 2014, respectively. The canopy chamber measures instantaneous CER fluxes, and daily and daytime cumulative CO₂ values were calculated from the instantaneous CER. The chamber CER results were compared with nearby eddy covariance (EC) flux tower measurements at a variety of time scales, i.e., instantaneous, daily, and daytime cumulative (multiple months). The daily and daytime cumulative chamber CER values were within 5% of the EC results, providing evidence for the effectiveness of the portable canopy chamber method. In conclusion, the portable canopy chamber provides reliable CO₂ flux measurements despite the small size of field plots.
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