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Yard Waste 4039
Composted yard waste makes up a quarter of the U.S. recycling rate.
3 Min Read
Yard waste includes grass, leaves, and tree and brush trimmings. By weight, grass is the biggest component of yard waste, averaging half of all yard waste. Leaves and brush each provide one quarter. By volume, leaves are the biggest component.
Yard waste is the largest component of generated municipal solid waste (MSW) by weight but is a relatively small component of landfilled MSW by volume.
The amount of yard waste and its MSW disposal market share declined dramatically in the last four decades while the composting rate soared. Backyard compost piles and grasscycling programs have reduced yard waste generation. State and local composting requirements increased the number of commercial composting operations.
Composting is the controlled decomposition of organic matter by microorganisms into a humus-like product. Waste and carbon dioxide dissipate into the atmosphere. Up to 75 percent of the volume and 50 percent of the weight are lost through composting.
Aeration, temperature control (132-140 degrees F), moisture content (40-60 percent) and an adequate carbon-to-nitrogen ratio are required for composting. Improper operation can cause odors and allow the growth of a fungus (aspergillus fumigatus) that causes health problems.
Chaz Miller is state programs director for the National Solid Wastes Management Association, Washington. E-mail him at: [email protected].
YARD WASTE MSW FACTS
Generated:
32.6 million tons, or 12.8% by weight.
216.3 pounds per person, per year.
Composted:
20.9 million tons, or 64.1%.
3,500 yard waste composting facilities, mostly in the Northeast and the Midwest.
Average daily throughput is 57,300 tons.
Compost can be produced in as little as three months.
Composted yard waste accounts for one-fourth of the U.S. recycling rate.
Incinerated or Landfilled:
11.7 million tons, or 6.9% of discarded MSW.
Percentage sent to disposal has steadily declined for the last three decades.
2,876 Btu per pound vs. 4,500-5,000 Btu for a pound of garbage.
Several states ban the burning of yard waste piles.
24 states ban or restrict yard waste disposal.
Landfill Volume:
21.7 million cubic yards in 1997.
5.1% of landfilled MSW in 1997.
Density:
Uncompacted is 250-500 pounds per cubic yard (cu. yd.).
Landfilled is 1,500 pounds per cubic yard.
Source Reduction:
Grasscycling ("leave it on the lawn" programs) and backyard composting made yard waste the most source-reduced item in the waste stream.
Brush can be shredded into mulch.
Xeriscaping (landscaping with plants that need small amounts of water and produce small amounts of waste) reduces yard waste.
Composting Markets:
Composted yard waste is a soil conditioner that improves texture, air circulation, and drainage, moderates soil temperature, enhances nutrient and water-holding capacity, decreases erosion, inhibits weed growth, and suppresses some plant pathogens.
High-quality compost is used as a soil amendment and mulch.
Compost can be used as landfill daily cover.
Compost processors often charge a tipping fee.
End-Market Specifications:
Vary by market.
Keep non-organic materials out.
Little heavy metal contamination.
SOURCES:
Biocycle magazine, April 2006, www.biocycle.com
"Municipal Solid Waste in the United States: 2007 Facts and Figures," U.S. EPA, Office of Solid Waste, www.epa.gov/osw
Composting Council, www.compostingcouncil.org
Cornell Waste Management Institute, www.cfe.cornell.edu/compost
"Measurement Standards and Reporting Guidelines," National Recycling Coalition, www.nrc-recycle.org
Data is from 2007 EPA estimates, except where noted.
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