Turfgrasses, Carbon Dioxide and Global Warming (Part 2 of 2)
Thomas J. Samples, Ph.D. - Plant Sciences Department, The University of Tennessee
More than 49 million acres of urban land in the U.S. are covered by turfgrasses (h). After absorbing CO2 from the atmosphere, turfgrasses produce, or synthesize, a number of sugars that can be transported to, and eventually become a part of, plant roots. Sequestered C in turfgrass soils is often a combination of decomposing roots and shoots that have been mixed with soil.
Research indicates that turfgrasses may sequester up to 800 pounds of atmospheric C per acre per year (l). Based on this estimate, urban turfgrasses in the U.S. could remove about 20 million tons of C from the atmosphere annually (e).
Researchers Ronald F. Follett (USDA-ARS Soil-Plant-Nutrient Research Unit, Ft. Collins, CO) and Yaling L. Qian (Dep. of Hortic. and Landscape Architecture, Colorado State University, Ft. Collins, CO) are studying the impact of turfgrasses on C levels in soil. They report that, in Colorado, four years after turf establishment, about 14 to 16 percent of the soil organic C (SOC) at a depth from 0 to 4 inches, and 7 to 11 percent of the SOC at a depth of 4 to 8 inches, came from turfgrasses (l). Fine fescue and creeping bentgrass sequestered more C than Kentucky bluegrass (l). In a previous study of 15 golf courses near Denver and Ft. Collins, CO, and one golf course near Saratoga, WY, research results show that, after turfgrasses are established, C sequestration continues for up to 31 years in fairways and 45 years in putting greens (m). Most rapid SOC increases take place during the first 25 to 30 years (m).
Trade-in, greenhouse gas 'offsets' paid by companies and individuals worldwide may total more than $100 million this year (n). The Outdoor Power Equipment Institute suggests that homeowners managing lawns may not need to look any further for a C offset than their own back yard (I). According to a research report by Ranajit Sahu, turfgrass in an average-managed lawn removes four times more C from the air, and a well-managed lawn, five to seven times more C from the air, than is produced by today's typical lawn mower (o).
Perhaps the efforts of golf course superintendents, homeowners, landscapers, lawn care professionals, parks and recreation department employees and sports turf managers to improve the overall quality of turf are more beneficial and important than ever before.
References:
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b. Anonymous. 2007. Cold storage solution for global warming? Carbon dioxide could be frozen in underground reservoirs. ScienceNews. February. http://www.sciencedaily.com
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I. Kiser, K. 2008. For carbon offset, look no further than your own backyard. Outdoor Power Equipment Institute. http://www.opei.org
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l. Qian, Y. and R. Follett. 2008. Soil organic carbon input from urban turfgrasses. 2008 Joint Meeting of the Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM. 68-2.
m. Qian, Y. and R. F. Follett. 2002. Assessing soil carbon sequestration in turfgrass systems using long-term soil testing data. American Society of Agronomy. Agron. J.: 94:930-935.
n. Revkin, A.C. 2007. Carbon neutral is hip, but is it green? New York Times. April 29.
o. Sahu, R. 2008. Research report: Technical assessment of the carbon sequestration potential of managed turfgrass in the United States. Outdoor Power Equipment Institute, Inc. http://www.opei.org
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