The Thermo-climatic Cost of a Lush, Green Lawn: Characterizing N2O emissions from lawns

Abstract

Quantification of nitrous oxide (N2O) emissions from lawns is important in creating complete regional greenhouse gas (GHG) inventories. To provide an estimate of these emissions from lawns, closed chamber sampling and modeling using DNDC was performed at lawns in the Richland Creek Watershed (RCW) in Metropolitan Nashville, Tennessee. Sampled N2O fluxes were ordinarily small and sometimes negative. Estimated annual emissions ranged from 1.91-11.1 kg N2O-N/ha/yr across sample sites, a rate of N2O emissions in line with measurements made on grasslands in Ireland that experience similar annual precipitation to the RCW. The model was then used to simulate the effects of different lawn care practices on N2O emissions and nitrate leaching and to provide a crude bound on N2O emissions and nitrate leaching from residential lawns at the watershed and regional scales. Emissions of N2O from lawns in southeastern cities with population >100,000 were estimated to be nearly 95% of the value reported for ‘settlements remaining settlements’ in the U.S. Climate Action Report (2010). This result suggests that N2O emissions from residential lawns may be an important source of GHGs, and more work needs to be done to adequately quantify these emissions for GHG inventories.