Net Carbon Sequestration Potential and Emissions in Home Lawn Turfgrasses of the United States

Soil analyses were conducted on home lawns across diverse ecoregions of the U.S. to determine the soil organic carbon (SOC) sink capacity of turfgrass soils. Establishment of lawns sequestered SOC over time. Due to variations in ecoregions, sequestration rates varied among sites from 0.9 Mg carbon (C) ha⁻¹ year⁻¹ to 5.4 Mg C ha⁻¹ year⁻¹. Potential SOC sink capacity also varied among sites ranging from 20.8 ± 1.0–96.3 ± 6.0 Mg C ha⁻¹. Average sequestration rate and sink capacity for all sites sampled were 2.8 ± 0.3 Mg C ha⁻¹ year⁻¹ and 45.8 ± 3.5 Mg C ha⁻¹, respectively. Additionally, the hidden carbon costs (HCC) due to lawn mowing (189.7 kg Ce (carbon equivalent) ha⁻¹ year⁻¹) and fertilizer use (63.6 kg Ce ha⁻¹ year⁻¹) for all sites totaled 254.3 kg Ce ha⁻¹ year⁻¹. Considering home lawn SOC sink capacity and HCC, mean home lawn sequestration was completely negated 184 years post establishment. The potential SOC sink capacity of home lawns in the U.S. was estimated at 496.3 Tg C, with HCC of between 2,504.1 Gg Ce year⁻¹ under low management regimes and 7551.4 Gg Ce year⁻¹ under high management. This leads to a carbon-positive system for between 66 and 199 years in U.S. home lawns. More efficient and reduction of C-intensive maintenance practices could increase the overall sequestration longevity of home lawns and improve their climate change mitigation potential.