Effects of growth substrate on greenhouse gas emissions from three annual species

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: 1/15/2020
Publication Date: 6/30/2021
Citation: Murphy, A., Runion, G.B., Prior, S.A., Torbert III, H.A., Sibley, J.L., Fain, G.B., Pickens, J. 2021. Effects of growth substrate on greenhouse gas emissions from three annual species. Journal of Environmental Horticulture. 39(2):53-61. https://doi.org/10.24266/0738-2898-39.2.53.
DOI: https://doi.org/10.24266/0738-2898-39.2.53

Interpretive Summary: Little work has been done on reducing greenhouse gas GHG (GHG = carbon dioxide, methane, and nitrous oxide) emissions in specialty crops of horticulture. The ornamental plant production industry could impact global climate change, and may reap economic benefits from potential changes in legislation or tax incentives aimed at reducing GHG emissions. Previous work has focused on plants grown in a bark-based substrate, while the current work evaluated three annual species grown in a standard peat:perlite greenhouse media, and two alternative substrates with varying percentages of high wood fiber. No differences were observed for main effects of species or media for N2O and CH4. Results for cumulative CO2 efflux indicated that substrate amended with up to 20% of a high wood fiber substrate (effectively replacing perlite) had similar CO2 emissions to the standard peat:perlite blend. This is promising for growers looking to identify a more sustainable substrate alternative to perlite, without increasing GHG emissions.

Technical Abstract: Previous work by these authors have quantified cumulative greenhouse gas (GHG) emissions for several woody and herbaceous perennial species, in interaction with several standard best management practices (container size, fertilizer application and irrigation delivery methods, and light level). In this study, the greenhouse production of three annual species (Solenostemon scutellarioides Thonn. ‘Redhead’, Catharanthus roseus L. ‘Cooler Grape’, Impatiens walleriana Hook. f. ‘Super Elfin XP White’) was evaluated in three substrates [80:20 peat:perlite, 80:20 peat:WholeTree (a whole pine based substrate), 60:40 peat:WholeTree]. Emissions of CO2, N2O and CH4 were collected over a period of 52 days. Without regard to media, coleus had the highest cumulative CO2 efflux (statistically similar to vinca), due to its increased size in comparison with both vinca and impatiens. Without regard to species, plant-pot systems using the highest proportion of WholeTree (40%) had the most cumulative CO2 efflux (statistically similar to those containing only 20% WholeTree). No differences were observed for main effects of species or media for N2O or CH4. Results suggest that using a more sustainable high wood fiber substrate in similar proportions to that of perlite in an industry standard mix could yield similarly sized plants with no negative impact on GHG emissions.