The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council. |
Monday, January 28, 2008
55
Lawn Clippings as a Biofuel Source
Tim L. Springer, Agricultural Research Service, USDA, Southern Plain Range Research Station, 2000 18th Street, Woodward, OK 73801
Biomass yield from urban landscapes is an untapped resource. Lawn clippings, fallen leaves and tree limbs are all potential sources of biofuels and most cities already collect and transport these materials to disposal sites. Cities could alternatively collect and transport these biomass materials to a local biomass fueled energy conversion plant. In 2007, an experiment was begun to evaluate the yield potential of a bermudagrass [Cynodon dactylon (L.) Pers.] lawn in Woodward, OK and to estimate the potential biomass yield for the City of Woodward. A typical lawn was thatched and fertilized with 13-13-13 (N-P-K) fertilizer at the rate 10 lbs bulk material per 1000 ft2 on 15 April. Mowing began on 18 May and every 10-14 days thereafter. The yield potential was estimated for each mowing date by harvesting four 166 square feet areas. The harvested material was weighed fresh, a 0.3-0.5 lb subsample collected and dried, and DM determined. The total DM of each sample was calculated by multiplying the percentage DM of the oven-dried sample by the harvested green weight of the sample. A preliminary estimate for 15 April-21 July shows that a typical lawn yielded 1,010 lbs of dry biomass material. This is equivalent to 4.6 tons/acre. It is also estimated that 3,600 tons of biomass material could be collected in the City of Woodward over that same period if every homeowner collected there lawn clippings. The typical growing season for bermudagrass in NW Oklahoma is May through September. Thus, it is possible that the reported biomass yields could double by the end of the growing season.