Compostable materials are those which biodegrade completely into substances which are healthy or at least harmless for soil and plants. In general, anything which was once living can be composted, although some materials are more convenient to process than others. To be on the safe side, always wear gloves when handling compost, and try to avoid allowing compost to have any contact with eyes, mouth, or breaks in skin.
List of compostable materials[edit | edit source]
Plant materials[edit | edit source]
In general, plant-based materials are easy to handle and pose fewer health risks to humans.
- Coffee grounds
- Some tea bags (a staple may be ok, but many bags sold in the US contain a small amount of plastic. This is not very harmful, but is not perfectly compostable - you can tear off the top and throw in the regular garbage, and just compost the tea leaves & lower portion of the bag.)
- Green waste from the garden, dead tomato plants after the autumn frost, weeds, etc.
- Yard waste (lawn and hedge clippings). Woody waste will degrade faster if you shred it before adding it to the pile. Large intact limbs may take years to fully decay. If you cannot reduce the size of large wood chunks, place them toward the bottom of the pile so they are subject to the most possible heat and moisture.
- Leaves - if you live around deciduous trees, you can collect huge amounts of leaves for your compost pile. If your neighbors place their leaves and yard waste at the curb for collection, you can rescue it for your compost pile, thus saving the fuel cost of hauling it to a central processing facility. To reduce the volume of fresh leaves as quickly as possible, shovel old compost over them as you add them to the pile, and wet them down (preferably with graywater or rainwater rather than potable water). If no old compost is available, an alternative is to throw dirt on the pile, which will innoculate the leaves with microbes and break them down faster.
- Old mushroom compost
- Tree bark. Pine bark and some other forms of bark need to be composted for a period of some months to break down harmful components.
- Christmas trees - lop off the branches, add them to your pile, and save the trunks to use as very sturdy tomato stakes in your garden. You can set the trunks in the ground with a post-hole digger. After they rot and fall down you can compost them too. You can collect trees from all your neighbors when they discard them after Christmas. The branches take a long time to compost, unless you shred them first. If you can't shred them, put them directly on the ground, shovel old compost over them, and wait a year.
- Kitchen scraps containing no animal products - putrescible wastes (i.e., that stink) attract flies and larger scavengers. Follow the same precautions as for kitchen scraps containing animal products.
Animal materials[edit | edit source]
- Egg shells - straightforward to compost, add calcium to the final product
- Humanure (but take proper health precautions)
- Urine - easier to collect and pour on the pile than faeces, poses far less health risk, and provides most of the usable nitrogen from human waste. Nitrogen from urine will feed the microbes that break down brown (carbon) materials.
- Food scraps containing meat or bones - beware of pests. Meat scraps are often not advised as they can attract animals, but it depends on the context, the amount of meat, and whether the compost is securely covered. To eliminate odors and flies, shovel a thick layer of old compost or brown waste such as leaves over any fresh food scraps you add to the pile. It may help to arrange two piles, one that you add new material to, and one that you use as a source of old material to cover each addition of new material. While scavengers such as raccoons have extremely sensitive noses, there is a limit to how deeply they will dig into a compost pile. You can compost almost anything without attracting pests if you bury it deeply enough in unpalatable compost material. Materials such as meats, skin, etc. will become unpalatable in just a few days if the interior of the pile is active enough (i.e., hot and wet), but animal bones can remain attractive to pests for weeks. In cold weather, if the pile is dormant i.e. cold through the interior, food scraps may remain attractive to scavengers until the weather warms and decay resumes.
- Hair trimmings, nail trimmings from people or pets.
Man-made materials[edit | edit source]
- Compostable packaging - but ensure that any "plastic" is actually compostable, and not just "biodegradable" (i.e. breaking down into tiny pieces of plastic).