Compost happens when yard & food waste are combined with oxygen in a way that stimulates microbial decomposition. Microbes such as bacteria, fungi, and molds are attracted to the pile by carbon and nitrogen—their favorite foods. These microbes in turn entice organisms such as earthworms, millipedes, and beetles to the pile…and together they have the biggest food binge you’ve ever seen.
Successful composters use the right combination of “browns,” or carbon-rich ingredients, plus “greens,” or nitrogen-rich ingredients, to attract compost-producing organisms. The secret to their success is to remember the brown:green ration of 3:1—three parts carbon-rich ingredients for every one part nitrogen-rich ingredients.
Here's a list of the most commonly used browns & greens. These items should be shredded/crushed/broken down as much as possible to speed the decomposition process.
- Fall leaves
- Hay & straw, cornstalks
- Shredded cardboard & newspaper (newspaper inks are soy-based which are OK)
- Paper plates, bags, towels
- Chipped brush, sticks, twigs, branches, bark
- Pine needles (but not more than 10% of the pile)
- Vegetable & fruit wastes
- Coffee grounds, filters, & teabags
- Horse, cow, rabbit, chicken, gerbil, goat, sheep, rabbit, pig manure
- Weeds without weed seeds & other yard waste (without chemicals)
- Grass clippings (but not if you use harmful chemicals on your grass!)
- Seaweed (give it a good soak to remove excess salt)
What not to add. In theory, almost anything can be composted except the waste of humans, cats, & dogs. Commercial composters compost many things that those of us with home piles shouldn't, because they don't have to worry so much about bad odors, pests, or weeds. But as a general rule, avoid composting the following to keep your pile free of toxins, odors, pests such as rats, and weeds:
- Meat/pork, chicken, fish, bones
- Fat, grease, oils
- Peanut butter
- Dairy products
- Foods cooked with sauces or butter
- Dog, cat, or human waste
- Plants with diseases
- Weeds with seeds
- Weed vines
Remember, if you keep a ratio of 3 parts browns to 1 part greens, your compost will decompose faster and without a lot of odors. In actual practice here's what this means: get your pile started with 3 parts of your leftover fall leaves and yard waste and add one part vegetable & fruit scraps and mix. Continue to add food scraps and mix them in, making sure that you add additional browns as you go along to keep the ratio at 3:1.
I'll write more how to compost later, when to turn, hot vs. cold composting, pile/heap vs. bin, etc.
Willie the Worm courtesy of Michigan Dep't of Agriculture.