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 fertilizer properties, e.g., nitrogen, phosphorus, and potassium, that must be
included in calculations for fertilizer application.
Composting serves as an alternative method of managing those organics that would
otherwise be landfilled. Although up to 60 percent of municipal solid waste is potentially
compostable (including food and paper), yard trimmings are the least controversial feedstock
for compost. Yard trimmings composting returns grass, twigs; and leaves to the soil. When
grass clippings are included with leaves and other yard trimmings, the resulting compost can
serve as a suitable nitrogen source with an optimal carbon/nitrogen ratio for many
applications. A significant portion of the yard trimmings is being composted, and the
percentage is increasing. Oily 651 yard trimmings composting facilities were operating in
1988. This increased to more than 2,200 yard trimmings composting facilities at the end of
1991, continuing to increase to nearly 3,000 facilities at the end of 1993. Thus, the quantity
of compost available from local sources is expected to increase in the near future.
There is currently not a large amount of compost produced from mixed municipal
solid waste produced in the U.S. As of February 1993, there were 20 mixed municipal solid
waste composting facilities in operation, 10 pilot programs, and about 60 projects under
development. The amount of compost being produced from food scraps is even smaller,
with much of the current production coming from pilot projects.
High quality compost is fully "mature," which means that the cornposting process is
completed. Mature compost is free of pathogens and weed seeds. Compost is used as a soil
conditioner, soil amendment, lawn top dressing, potting soil mixture; rooting medium, and
mulch for shrubs and trees, and for improvement of golf and other sports turf. It has also
been used in erosion control, certain pollution prevention procedures (used to permanently
bind heavy metals in contaminated soils) and for soil reclamation. Compost can be used in
agriculture, horticulture, silviculture (growing of trees), and in landscaping. Compost can
also be used in land reclamation and revegetation of roadsides after road construction. An
important consideration for the compost purchaser is the availability of sufficient quantities of
high quality compost and certainty that it is of sufficiently high quality for its intended use.
Because of the high volume of yard trimmings currently discarded each year, there is no
current shortage of raw materials that would preclude composting facilities from supplying
large volumes of yard trimmings compost. Taken together, yard composts, biosolids
compost and mixed municipal composts are the most rapidly growing recycled content
products.
2. Summary of Comments and Agency's Response
a. Support for compost designation. EPA received four comments specific to its
proposal to designate yard trimmings compost as a guideline item in the CPG. Three
commenters expressed general agreement that yard compost should be a designated item.
b. National standards for compost. One commenter expressed concern about the
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