Please recommend me a digester/compost bin that produces compost fast

November 4, 2018 1:39 PM

So... I've got a bog standard compost bin outside (a round one about 1m high and about 0.5m wide), but I've already filled it up in about six months (mainly with food waste [no meat or dairy], some grass cutting and some rodent bedding waste) and the stuff at the bottom is still only half to three quarters done.

So... I've got a bog standard compost bin outside (a round one about 1m high and about 0.5m wide), but I've already filled it up in about six months (mainly with food waste [no meat or dairy], some grass cutting and some rodent bedding waste) and the stuff at the bottom is still only half to three quarters done. I've got a bit of a budget (£100 max), but I basically just want a compost/digester that will create compost faster, like maybe waste in and then compost out in six months or sooner if possible. Is there such a product on the market?

Thanks in advance,

Sockpim

posted by sockpim to Home & Garden (4 answers total)

I like a two-chamber tumbler (would link to mine but I think the UK has different makes). Reasonable summary. Have you been turning your single pile? Pre-tumbler, turning the whole thing over once a week was standard for me. This requires space for two piles, though.

I expect rodent bedding waste to support a lot of microbe activity, so the pile will prrrrrobablly get up to heat even in the smaller tumblers.
posted by clew at 1:47 PM on November 4, 2018 [2 favorites]

I've got two compost bins. One sounds like the one you've got now, and the other is a tumbler. The tumbler produces finished compost much faster. The only thing with that is that if you're continually putting waste in, then tumbling, you'll always have undigested food waste in with the finished compost, so you do kind of need two unless you're okay with some grossness when harvesting your finished compost. With the bin that I have that's like yours, I tend to periodically pull out the stuff at the bottom into another pile and then let my chickens roam through it for a while so they are turning it for me for a few weeks, but that bin is mostly yard waste, not food (for rodent control reasons).
posted by soren_lorensen at 1:52 PM on November 4, 2018 [1 favorite]

Best answer: Hotbin - we have something very like this, and it works very quickly. Big piles of waste become compost in a few months. We don't use it to its full potential (we're lax with the bulking side of things) but it makes good compost in any case and doesn't smell . Also has the advantage of being able to take food waste, because it really does get hot and things decompose quickly.
posted by Martha My Dear Prudence at 5:24 PM on November 4, 2018

I don't really believe there's a product you can buy to make compost work faster in a backyard context (I'm a horticulturalist with a strong interest in soil science). It's really about getting the recipe correct.

Here's what it takes to compost: about 25:1 ratio by weight, of (brown)carbon and (green) nitrogenous material; soil microorganisms; air; and moisture. Make sure your ratio is correct first and foremost so that you have the right kind of food for the microorganisms to work. They also need air and water, so keep it as wet as a wrung out sponge and be sure to toss it at least once a week. If particles are too fine and packed down that will cause aeration problems and anaerobic bacteria may take over. There's not really a product to help with these things, other than aeration. Unfortunately, rotating composters don't necessarily compost faster, they just make the stirring part easier. They have less access for all the wide range of critters that do the composting, and often can't retain heat as well as a pile on the ground. However if pile stirring is difficult, they can solve that problem. All the other components still need to be in order though.

Basically microorganisms convert organic materials to the inorganic nutrients that plants can take up. These successive populations rise and fall with C:N ratios and temperatures. What happens if this succession doesn't occur is incomplete conversion- often nitrogen, phosphorous, and sulfur are lost as a gas form to the atmosphere in artificially heated composters (or when anaerobic bacteria have taken over because the pile is too wet or not aerated). So heated composters can break down materials quickly, but it won't be nutritious in the same way as compost which is heated by the actions of bacteria converting the materials into plant-available nutrients.
posted by oneirodynia at 11:20 PM on November 4, 2018 [2 favorites]