T U R F TA L K
Turfgrasses AND
GLOBAL WARMING By Tom Samples, Ph.D., John Sorochan, Ph.D., and James Brosnan, Ph.D., Plant Sciences Department, The University of Tennessee hich of the following — light, temperature, water (H2O), atmospheric carbon dioxide (CO2) or nutrition — is most important for turfgrass survival? One correct answer: All are equally important. More difficult and complex questions are: “What is turfgrasses’ capacity to remove and store, or sequester, carbon (C) from the atmosphere?” and “Does this help prevent global warming?” These questions force us to recall what we’ve learned about photosynthesis (6CO2 + 6 H2O + light energy _C6H12O6 + 6O2), the ability of turfgrasses to capture and store C, the greenhouse effect and the oceans’ role in C sequestration. Approximately one-half of the photosynthesis on Earth occurs on land, and the remainder occurs in water. Both ocean and land plants share the same basic requirements for photosynthesis and growth. These requirements include light, an appropriate temperature, H2O, CO2 and nutrients. Although the gases nitrogen (N2) and oxygen (O2) account for 78% and 21% of the dry atmosphere, respectively, they contribute very little to the greenhouse effect. Greenhouse gases in the atmosphere — including CO2, hydrofluorocarbons (HFCs), methane (CH4), nitrous oxide (N2O), ozone (O3), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and water vapor — act as a partial blanket for long-wave radiation coming from the earth’s surface. They let energy from the sun in, but they don’t let all of the heat energy out. This blanketing results in a natural greenhouse effect, warming the earth’s surface. Water vapor and CO2 are two very important greenhouse gases. Human activities have had only a small, direct influence on the amount of water vapor in the atmosphere. During the
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TENNESSEE TURFGRASS
FEBRUARY/MARCH 2009
Email TTA at: tnturfgrassassn@aol.com