Our county master gardener who teaches composting emailed me the link and doc below. The composting method at the link is simpler than the method she outlined below. We had a detailed phone conversation and here are my notes.
- Efficient composting requires the right mix of nitrogen (greens), carbon (browns), oxygen and water
- 1 cu. yd. is the minimum compost pile size for holding heat well; there is no maximum size
- Have a collecting bin or garbage can for incoming greens until you have enough
- Start a new pile with 2 parts browns to 1 part greens by volume, mix it all at once
- Add water as you mix the pile, moist by not dripping
- Left undisturbed the pile should reach 120+ deg in 2 days; if not, add more greens
- Left undisturbed the pile should reach 130-160 deg in 3-5 days
- At 7-10 days or 100 deg, turn the pile. Repeat this 3-4 more times or when pile no long reheats.
- Best to turn inside-out since the center is the hottest. Mix in water so only moist, not dripping
- Let the compost age for 4-8 weeks; otherwise, it will draw nitrogen from the soil when applied
- This full cycle is then 2 to 3 months
- If you don't mix browns/greens all at once and don't let the pile sit, then it cools and takes longer
- She's measured 140 deg piles even in winter
- Longer, cooler wait periods are ok but 7-10 days or 100 deg are the most efficient to turn
- Hot composting, as above, is more effort and needs more materials all at once
- Cold composting is much easier but can take a year or more, plus leach nutrients, attract pests
- The two main cold composting examples are leaf piles and straw+manure, both left to sit
- A high peak temperature helps kill volunteer seed
- Different aerobic bacterial take over at different temperatures; bacteria get air during pile turns
- Worms will self manage and seek the cooler parts of the pile
- Is not enough rain in Central Oregon so don't cover piles with tarps; it would also reduce air
- Browns: sawdust is the highest nitrogen. Straw is good along with leaves. Newspapers are ok.
- Suggests no dirt; it adds weight and is a low-quality brown
- Greens: the variety of greens we have is very good; composting is more efficient if chopped smaller, 1" or less
- Suggests bins with screen sides or screened-pallets for better air, not straw bails or solid walls
- One oxygen vent pipe is enough for our current bin; more would cool the core too much
Here is the link to the composting publication.
Here is the handout for you explaining what we talked about on the phone,
