|Wall, Gerard - Gary|
|KIMBALL, BRUCE - Collaborator|
|OTTMAN, MICHAEL - University Of Arizona|
|GARCIA, RICHARD - Li-Cor, Inc|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/21/2012
Publication Date: 3/11/2013
Citation: Wall, G.W., Mclain, J.E., Kimball, B.A., White, J.W., Ottman, M.J., Garcia, R.L. 2013. Infrared warming affects intrarow soil carbon dioxide efflux during early vegetative growth of spring wheat. Agronomy Journal. 105(3):607-618.
Interpretive Summary: The Earth is warming globally, which may affect carbon dynamics in agricultural soils where wheat – the world’s foremost food and feed crop – is grown. A warming apparatus was used to increase the canopy temperature of a spring wheat crop by 1.5 and 3.0°C during the day and night periods, respectively. From planting until the wheat crop filled the intrarow space soil carbon efflux was measured. Under well watered conditions warming increased soil carbon efflux in the intrarow space of the wheat crop. Nevertheless, warming accelerated soil drying which ultimately caused a decrease in soil carbon efflux. Results suggest that carbon efflux processes in the intrarow space of a wheat crop are more complex than previously believed. But, our understanding of the effects of global warming on soil carbon efflux of a wheat crop will enable growers and end-users to make better use of their carbon resources in wheat producing regions of the world under conditions of global climate change.
Technical Abstract: Global warming will likely affect carbon cycles in agricultural soils. Our objective was to deploy infrared (IR) warming to characterize the effect of global warming on soil temperature (Ts), volumetric soil-water content ('s), and intrarow soil CO2 efflux (Fs) of an open-field spring wheat (Triticum aestivum L. cv. Yecora Rojo) crop grown in the semiarid desert Southwest. A temperature free-air controlled enhancement (T-FACE) apparatus using IR heaters maintained canopy air temperature above 3.0-m plots by 1.3 and 2.7°C (0.2 and 0.3°C below the targeted set-points) during the diurnal and nocturnal periods, respectively. A randomized complete block (RCB) design with two IR warming treatments (i.e., Heated; Reference) in three replicates was planted on 10 Mar. and 1 Dec. 2008. Intrarow Ts, 's, and Fs were measured from emergence (bare soil) up until inflorescence emergence (canopy closure). Under ample soil water supply with high 's, midday Fs was 10% greater in Heated [4.1 µmol (CO2) m-2 s-1] compared with Reference [3.7 µmol (CO2) m-2 s-1]. In contrast, as the soil dried and 's decreased to a greater degree in Heated compared with Reference, a 10% decrease in Fs occurred in Heated compared with Reference. Overall, 's had the greatest impact on Fs, whereas it was responsive to Ts only under high 's. Accurate predictions of global climate change effects on Fs in agricultural soils require that interactive effects of Ts and 's be coupled. Infrared warming with T-FACE proved to be an effective experimental methodology to investigate these interactive effects.