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Featured Turfgrass Article
Carbon Sequestration and Microbial Populations in Turfgrass Landscapes Author: Joseph Young Ph.D. , Texas Tech University, Plant and Soil Science Department
Popular media and many urban residents seem to undermine the benefits natural turfgrass landscapes provide to the environment and betterment of society. However, one such benefit that has been studied extensively across the US is carbon sequestration potential of lawn grasses (1, 2), and newer research is identifying the vast array of beneficial microorganisms associated with natural turfgrasses (3, 4, 5). Researchers from Texas Tech University’s Plant and Soil Science department recently completed research in this area to estimate carbon sequestration potential and characterize soil microbial populations of urban turfgrass landscapes. Carbon Sequestration Potential As carbon dioxide levels in our atmosphere continue rising, turfgrasses and other photosynthesizing plants are benefiting by transforming atmospheric carbon dioxide into more stable forms of carbon stored in the soil. The capture and subsequent storage of carbon is called sequestration. Previous research has suggested turfgrasses have potential to sequester and safely store between 0.08 to 2.27 tons carbon per acre per year with variation depending on climate (annual temperature and moisture), soil texture, plant species selection, or previous land use. Our research team set out to determine carbon sequestration potential of residential lawns throughout Lubbock by collecting soil samples (4-inch depth) from yards of homes built prior to 1970, 19711990, 1991-2010, and after 2011. We did assume there had not been any drastic alterations to the landscape since home construction and used previous satellite imagery from each property to confirm similar landscape design since the late 1990’s. Soil samples obtained from 40 residential lawns (10 lawns within each age group) were used to establish the carbon sequestration rate of 0.1 tons carbon per acre each year reaching maximum storage in the upper 4 inches at 53.6 years. Once maximum storage is reached (approximately 5 tons carbon per acre), an equilibrium is reached where relatively equal portions of the stable soil carbon pool are degraded by microorganisms as would be added through photosynthetic production and plant growth. When considering an individual’s piece of residential property, the calculated carbon sequestration rate can feel a little “worthless”, especially when estimates suggest each human person expends 16 to 27 tons of carbon each year (6, 7). However, when you begin to add up the acreage of residential lawns across highly populated cities, managed parks, athletic field complexes, and golf courses; these incremental carbon storage bank accounts can become a significant contributor to decreasing atmospheric carbon. Characterizing Microbial Populations in Turfgrass Soils The number of microbial organisms living in soil is astounding and almost unbelievable as it has been estimated that one gram of soil may contain up to 10 billion microorganisms! These soil microbes provide many benefits to soil, plants, and the environment such as decomposition, essential plant nutrient cycling, pesticide degradation, and bioremediation.