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Title: Soil carbon as affected by horticultural species and growth media

item MARBLE, S - Auburn University
item Prior, Stephen - Steve
item Runion, George
item Torbert, Henry - Allen
item GILLIAM, C - Auburn University
item FAIN, G - Auburn University
item SIBLEY, J - Auburn University
item KNIGHT, P - Auburn University

Submitted to: Southern Nursery Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/8/2010
Publication Date: 8/1/2011
Citation: Marble, S.C., Prior, S.A., Runion, G.B., Torbert III, H.A., Gilliam, C.H., Fain, G.B., Sibley, J.L., Knight, P.R. 2011. Soil carbon as affected by horticultural species and growth media. Southern Nursery Association Proceedings, January 19-20, 2011, Mobile, Alabama. 56:345-350.

Interpretive Summary: The global climate may be altered by increases in atmospheric CO2 concentration. The majority of work on soil carbon storage has been done in crop and forest systems with little attention being placed on horticulture plantings in the urban landscape. Our objective was to determine the effects of standard and alternative potting mixtures on soil carbon levels when commonly grown horticultural species are planted into the landscape. Our findings show that the addition of media from container-grown plants increased soil carbon levels 4 to 12 times more than soil carbon levels seen in native soils. Such increases are much larger than that observed in crop and forest systems.

Technical Abstract: Increasing atmospheric concentrations of greenhouse gases (GHG) are widely believed to be a main contributing factor to climate change. United States agriculture is one of the largest contributors of GHG emissions, trailing only energy production, which leads scientists to believe that emissions from agriculture must be reduced to slow climate change. However, emission reductions alone may not sufficiently curtail negative environmental impacts and, therefore, long-term capture and storage of carbon (C) will be necessary. To date, most research on GHG emissions and C sequestration has focused on row crop and forest systems with virtually no work on ornamental horticulture. Farmers in other agricultural sectors are now earning additional income in the emerging C trading market for reducing C emissions and pledging to alter management practices which will provide C offsets by increasing C sequestration. The ornamental horticulture industry also has the potential to sequester C through transplanting container-grown ornamentals into urban and suburban landscapes which sequester C in biomass and soils. In addition, transplant growth media can be an additional C sink that has not been accounted for in previous research. Our data shows that when ornamental species are planted in the landscape, the addition of media from container-grown plant production increased soil carbon levels 4 to 12 times higher than soil C levels observed in native soils. If future legislation requires caps to be placed on agricultural emissions, the horticulture industry will need to demonstrate possible benefits it has on the atmospheric environment. The objective of this research is to determine the effects of growth media on soil carbon levels from commonly grown horticultural species planted into the landscape.