Effects of fertilizer placement on greenhouse gas emissions from a sun and shade grown ornamental crop

Authors: MURPHY, ANNA-MARIE - Auburn University; Runion, George; Prior, Stephen - Steve; Torbert, Henry - Allen; SIBLEY, JEFF - Auburn University; FAIN, GLENN - Auburn University; PICKENS, JEREMY - Auburn University

Submitted to: Journal of Environmental Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2019
Publication Date: 10/21/2019
Citation: Murphy, A., Runion, G.B., Prior, S.A., Torbert III, H.A., Sibley, J.L., Fain, G.B., Pickens, J. 2019. Effects of fertilizer placement on greenhouse gas emissions from a sun and shade grown ornamental crop. Journal of Environmental Horticulture. 37(3):74-80.

Interpretive Summary: Release of greenhouse gases (GHG = carbon dioxide, methane, and nitrous oxide) to the atmosphere are factors influencing climate change. Little work has been done on reducing GHG emissions in specialty crops of horticulture. We looked at how fertilizer placement (dibble, incorporated, top-dress) affects GHG loss using a shade-grown species (hosta) and a sun-grown species (daylily) grown in 1 gal containers under standard conditions. Dibbling fertilizer reduced both CO2 and N2O emissions in both hosta and daylily. Methane release was low throughout the study and not impacted by fertilizer placement in both species. Findings indicate that dibble fertilizer placement could decrease both CO2 and N2O emissions.

Technical Abstract: Previous work has begun to establish baseline approximations for greenhouse gas (GHG) (CO2, CH4, and N2O) emissions of several horticultural crops, though much work is still needed to expand contingencies for multiple best management practices. In this study, GHG emissions from one shade-grown perennial, ‘Royal Standard’ hosta (Hosta ‘Royal Standard’), and one sun-grown perennial, ‘Stella D’Oro’ daylily (Hemerocallis ‘Stella D’Oro’), were evaluated in standard bark-based substrates with one of three fertilizer methods (dibbling, incorporated, or top-dressed) (25 g per container of Polyon 16-5-10, 12-month release + micros). Plants were grown in 3.5 L (1 gal) nursery containers, and irrigated with overhead irrigation calibrated to deliver 6.35 mm (0.25 in) water three times daily. Gas samples were collected in situ once weekly over a 5-month period using the static closed chamber method according to standard protocols and analyzed using gas chromatography. Both CO2 and N2O total cumulative efflux was least for plants fertilized with the dibbled method, regardless of species. Total cumulative CO2 emissions were greatest for both daylily and hosta with incorporated fertilizer, though in the case of the sun-grown daylily, CO2 efflux was similar among plants with fertilizer that had been either incorporated or top-dressed. There were no differences in N2O efflux for both the incorporated and top-dressed treatments of shade-grown hostas and sun-grown daylilys. Methane (CH4) efflux was consistently low throughout the study. Commensurate with previous work, daily CO2 and N2O emissions experienced a spike at study initiation. In general, daily CO2 efflux was greater for shade-grown hosta than for daylily, while initial spikes in daily N2O emissions were greater for sun-grown daylily than for shade-grown hosta. Findings suggest that utilizing a dibbled fertilizer placement could significantly decrease both CO2 and N2O emission.