Biomass yield from an urban landscape

Utilizing biomass from urban landscapes could significantly contribute to renewable energy needs. An experiment was begun in 2007 to evaluate the biomass production from a bermudagrass, Cynodon dactylon var. dactylon (L.) Pers., lawn in Woodward, Oklahoma USA and to estimate the potential biomass yield for the City of Woodward. Each year in April, the lawn was dethatched and fertilized. Mowing began in mid-to-late May and biomass dry matter (DM) yield was estimated by harvesting four 1 m × 16 m areas. In addition, the DM yield of fallen leaves and tree limbs from pruning operations were added to the lawn yield estimates for total annual biomass potential. These data suggest that during years of high growing season precipitation it was possible to harvest from 13.5 to 19.0 Mg of DM biomass per planted hectare from an urban landscape and 8.0 to 12.3 Mg of DM biomass per planted hectare in years with near normal precipitation and temperatures. It was estimated that the City of Woodward could generate about 3750 Mg of biomass dry matter in a normal rainfall year and about 6100 Mg in a high rainfall year if every homeowner collected their lawn thatch and clippings, and tree leaves, twigs, and limbs for bioenergy production. On the basis of a 10 Mg ha−1 annual DM yield, an estimated 164 million Mg of dry biomass material could be collected in the USA from planted urban areas. Biomass from urban landscapes is an untapped resource and further research is needed to fully explore its potential.

► Urban biomass could significantly contribute to renewable energy needs.
► Lawn clippings, fallen leaves and tree limbs are all potential sources of biofuels.
► Urban biomass is an unused resource.
► 8.0–12.3 Mg of dry biomass per planted hectare in an average rainfall year.
► 13.5–19.0 Mg of dry biomass per planted hectare in a high rainfall year.