Carbon Accounting for Compost Use in Urban Areas

Urban Farm DB summary

This study modeled the carbon benefits and costs of biosolids compost use in King County, Washington. Soil carbon sequestration was highest for use on disturbed soils, such as new housing developments, neglected urban soils, or highway right-of-ways (–1.1 Mg CO2eq per Mg compost), and lowest for use in well-tended yards or other highly maintained landscapes (–0.036 Mg CO2eq per Mg compost). Compost use for tree growth, calculated over a 30-year period, added above-ground sequestration benefits ranging from –1.53 Mg CO2eq per Mg compost for a mature tree grown on a healthy soil to –4.58 Mg CO2eq per Mg compost for a newly planted tree grown on a disturbed site. Assuming a 20 km haul distance, transport costs ranged from 0.005 Mg CO2eq per Mg compost for delivery in a 5 Mg truck to 0.09 Mg CO2eq per Mg compost for pick up in a personal vehicle.