Greenhouse gas emissions from an ornamental crop as impacted by two best management practices: irrigation delivery and fertilizer placement

Authors: MURPHY, ANNA-MARIE - Auburn University; Runion, George; Prior, Stephen - Steve; Torbert, Henry - Allen; SIBLEY, JEFF - Auburn University; GILLIAM, CHARLES - Auburn University

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2018
Publication Date: 8/3/2018
Citation: Murphy, A., Runion, G.B., Prior, S.A., Torbert III, H.A., Sibley, J., Gilliam, C. 2018. Greenhouse gas emissions from an ornamental crop as impacted by two best management practices: Irrigation delivery and fertilizer placement. Journal of Environmental Horticulture. 36(2):58-65.

Interpretive Summary: The rising level of greenhouse gases (GHG = carbon dioxide, methane, and nitrous oxide) in the atmosphere are thought to be factors causing climate change. Agriculture is known to be one of the largest contributors of these GHGs. Research on reducing agricultural GHG loss to the atmosphere has focused on row crops, pastures, forestry, and animal production systems. However, little work has been done in specialty crop industries such as horticulture. We looked at how irrigation (overhead vs drip) and fertilizer placement (dibble vs incorporated) might affect GHG loss using Japanese boxwood (Buxus microphylla) grown in 11.4 L (3 gal) containers with a 6:1 pine bark:sand growth media and incorporated with standard fertilizers. Containers received 6.35 mm (0.25 in) of water three times a day. Gas samples were collected and measured for GHGs once or twice a week over a growing season using standard methods. Total carbon dioxide loss was not affected by differences in irrigation or fertilizer placement. Total nitrous oxide loss was least for drip-irrigated plants, regardless of fertilizer placement. For overhead-irrigated plants, nitrous oxide loss was greatest for containers with incorporated fertilizer. Loss of methane was low throughout the study. Our findings suggest that using drip irrigation could decrease nitrous oxide loss, regardless of fertilizer placement. However, when limited to overhead irrigation, dibbled fertilizer placement could decrease nitrous oxide loss.

Technical Abstract: Agriculture is a one of the largest contributors to trace gas emissions. To date, much work on reducing greenhouse gas (GHG) emissions has centered on row crops, pastures, forestry, and animal production systems, while little emphasis has been placed on specialty crop industries such as horticulture. In this horticulture container study, Japanese boxwood (Buxus microphylla) was used to evaluate the interaction of irrigation (overhead vs drip) and fertilizer placement (dibble vs incorporated) on trace gas emissions (carbon dioxide, methane, and nitrous oxide). Plants were grown in 11.4 L (3 gal) containers with a 6:1 pine bark:sand growth media and incorporated with standard amendments; unfertilized (control) containers were included for background GHG emissions. All containers received 6.35 mm (0.25 in) water three times daily. Gas samples were collected in situ using the static closed chamber method according to standard protocols and analyzed using gas chromatography. Total cumulative CO2 loss was not affected by differences in irrigation or fertilizer placement. Total cumulative N2O efflux was least for drip-irrigated plants, regardless of fertilizer placement. For overhead-irrigated plants, N2O efflux was greatest for those with incorporated fertilizer. Efflux of CH4 was generally low throughout the study. Findings suggest that utilizing drip irrigation could decrease N2O emissions, regardless of fertilizer placement. However, when limited to overhead irrigation, dibbled fertilizer placement could decrease N2O emissions.