The Carbon Footprint of Colorado Golf Courses Estimated by Clubhouse Energy Use, Trace Gas Emissions and Modeling Carbon Sequestration.

Protecting soil organic carbon (SOC) is a critical factor concerning proper land stewardship. Intense research has been conducted on U.S. agricultural lands to evaluate carbon (C) sequestration rates as a means to retain national food security through sustaining soil integrity. More recently agricultural C sequestration and emissions from nitrous oxide (N2O) have been cited in research concerning global climate change. The leading cause of increased carbon dioxide (CO2), a known green house gas, is the direct result of fossil fuel use. Also in modern agriculture there is concern with the increased use of nitrogen fertilizer, which emits N2O another important GHG that degrades ozone and is 300 times more powerful than CO2 as a GHG. The atmospheric N2O stock is increasing at nearly 5 billion tons of nitrogen per year and while estimates are not completely certain of the specific sources of emissions, it is estimated that nearly 80% of N2O pollution comes from anthropogenic sources. However, land uses have begun to shift away from agricultural industries toward other urban practices such as turfgrass systems. While turfgrass does not produce agricultural goods, it still has a great deal of societal benefits which include soil erosion control, dust stabilization, reduced runoff, flood control, enhanced ground water recharge, and generates large amounts of revenue for the national economy of nearly $30 billion per year. There are approximately 20 million hectares (ha) of turfgrass in the U.S., which exceeds the 14.7 million ha enrolled in the Conservation Reserve program (CRP) during 2002. Since there is an ever growing amount of acreages being converted into turfgrass it is important to evaluate the overall efficiencies of these systems. Turf in Colorado is major industry that covers over 35,000 acres and generates approximately $15,700 per acre. Because turfgrass systems are perennial long lived grasses they contribute to an identified mitigation strategy of climate change by increasing SOC through C sequestration; this helps negate the adverse effects of this global problem by reducing atmospheric CO2. Turfgrass systems increase SOC by sequestering 1.0 to 0.9 megagrams (Mg) C/ha/ year for up to 25 to 30 years after turfgrass establishment. Collaborators established the “Colorado Carbon Project” in order to evaluate the C footprint of golf courses by collecting survey data for on course management practices, clubhouse energy uses and acreage types maintained on the facilities. Other detailed information regarding fertilizer use and rates, irrigation amounts, resources and energy costs for pumping, fuel types used, and age and location of course. Currently there are approximately 30 surveys that have been returned representing the major topographical regions of the state. This information will be used for estimating the C cost of energy uses based on CO2 equivalency equations. Also the information will be constructed into data for carbon and nitrogen ecosystem modeling using the newest version of Century model, Daily DayCent. The DayCent software enables timely and costly lab procedures to be scaled up. It is a multi-compartmental model that is highly sensitive to agricultural practices, soil texture, precipitation and temperature and the newest features simulate N2O, NOx emissions and N and H2O leaching. The Century model simulated 1.2 -0.9 Mg C/ha/yr, which is in close agreement with the measured data and demonstrates the appropriateness for using the model to simulate turfgrass systems. The final aspect to this study will include measurements of trace gas emissions using gas chromatography and sampling techniques and protocols for the chamber method. The trace gases will be measured at the one course near the USDA Fort Collins, CO laboratories. It is the efforts of this research that fertilizer and irrigation efficiencies can be improved through better understanding of application timings as well as other information regarding clubhouse energy audits.