What do I need to know to start an outdoor compost pile?
We’ve done a lot of composting in our urban back yard. We tried open piles, using some old wooden pallets, but the rats nested in the pile. We also tried some plastic bins, but had the same problems; nothing we could do would keep the rodents out. We figured that we should avoid ground contact. We’ve built a large composter out of a 55-gallon plastic apple juice barrel, and it’s fantastic. We also have an Envirocycle. Note that this model includes a resevoir for “compost tea.” Be sure to empty the resevoir regularly, or you’ll be treated to some really amazing smells. Since our yard is quite small, we collect leaves and grass clippings from the suburbs. We avoid yards that are unnaturally green, as we suspect those homeowners don’t share our organic sensibilities.
The real secret is that biodegradable matter composts by definition. All the tips and tricks are either to make things compost more quickly, less stinkily, or less full of racoons. My compost is in a fancy composter that I bought from the county at a discounted rate, but I’ve also composted perfectly well in a plastic garbage can that I cut the bottom off of and drilled lots of holes in the sides. I tend not to worry so much about the rules to keep things composting quickly. I do tend to put lots of leaves and grass clippings on top of any food scraps to keep the pile from smelling too much.
It’s simple. There are only a few things to know: 1. Use a container to keep raccoons, mice, etc. out 2. Avoid meats and fats. Eggshells are fine, and even some paper, like unbleached coffee filters. 3. Keep it slightly moist. 4. Turn it over regularly. It is the aerobic bacteria that work wonders with compost. The anerobic ones turn it into a stinky, slimy mess.
You’ll get a hot pile with a 30:1 C:N ratio. Carbon is the energy source for the microbes; as they oxidize it heat is produced. 30:1 is considered the optimum ratio to provide enough energy to maintain the bacteria long enough to break everything down. Adding more nitrogen doesn’t speed up aerobic composting- you end up with no energy to sustain the heterotrophic organisms that rely on organic carbon to function, and end up with an anaerobic pile that loses nitrogen to the atmosphere. Studies have found that around 50% of nitrogen was lost to the atmosphere when C:N ratios started at 20-25:1. Too low or too high a temperature will result in volatilization of nitrogen. Additionally, turning compost releases nitrogen to the air. This loss is minimized with a C:N ratio of 30:1 (incidentally, horse manure at 25-30:1 composts very well all by itself, while grass clippings at 12:1 need more carbon). The fastest possible compost is not necessarily a good thing. Under optimum conditions compos
