Composting Food Waste

Properly handled, kitchen waste—even the meat products usually excluded from piles—can be used successfully in a home composting system. However, check local health regulations before composting food scraps, since some municipalities have strict laws governing the disposal of such waste. For example, you may have to compost food scraps separately from nonfood waste. In some areas, you may be required to use a rat-resistant compost bin.

The most common problem in backyard compost piles is an unpleasant odor—and the usual cause is an excessive amount of either grass clippings or kitchen waste. In other words, the problem is too much nitrogen. You can always leave grass clippings on the lawn or use them as mulch to avoid having too much grass in the compost pile, but kitchen waste is a special situation. Stored in a container, especially a covered one, for more than a few days, kitchen waste begins to putrefy and reek. When this occurs outdoors, the food scraps attract flies and other pests.

When you add kitchen waste to a compost pile, be sure to cover it with a carbon-rich material, soil, or old compost to avoid odor and pest problems. Don’t include meat, bones, gravy, or fat in a passive pile or one that’s seldom turned. Even with a covering of carbon material, meat products usually attract pests.

When you add kitchen waste to a hot, actively managed pile, you don’t have to worry about excluding meat products and grease from the pile. The high level of microbial activity can handle those materials without odors or pest problems. Include bones in the pile if you wish. Although chicken bones and small beef bones won’t fully decompose even after a month or two in a hot, managed pile, they’ll lose their moisture and become dry and brittle. Sift them out of the finished compost and add them to the next pile. Or add them directly to the soil, where they’ll eventually break down and release phosphorus.

Another way to avoid problems with food waste in a compost pile is to run the waste through a blender or food processor before adding it to the heap. The material will settle down into the pile and won’t accumulate on top. The worms and other invertebrates in the outer layers of the pile make short work of this rich food, usually consuming it before it has time to decompose.

Ultimately, the best way to guard against problems is to compost kitchen waste separately in a compost tumbler, worm box, or other system that is designed to handle food.