What do I need to know to start an outdoor compost pile?

May 16, 2008 11:01 AM

I want to start composting, but I'm clueless: what do I need to know?

There's plenty of space, but family members will object to something that is too obviously a rotting pile of food and leaves. How do I start a pile, and what do I need to know in order to maintain it? Are commercial bins worth the cost?

I have no idea how to approach this, so any book recommendations, links to related blogs/other useful online resources, or suggestions for a course of action would be greatly appreciated.

posted by davidriley to home & garden (24 comments total)

You can get a composter which might be more visually acceptable, and it makes things easier. The main thing is to put in lots of nitrogen sources like grass clippings, green leafy things. No fat or animal products. There are tons of resources on the net for help. As for leaves, leave out the brown leaves in the fall. They are a special composting project and will slow down a regular pile. Food waste from the kitchen which might attract scavengers should be buried in the pile.
posted by caddis at 11:15 AM on May 16

Think worm beds too if the situation permits, fun little fellas
posted by Freedomboy at 11:28 AM on May 16

There are lots and lots of guides on the Internet, including this which I used a lot when I got started last year. It's thorough and has great lists of what should go in/what shouldn't go in/how to keep the compost puttering along on the road to great-looking and great-smelling dirt. Since they sell equipment, they tend to overemphasize how much stuff you need -- I just use a pitchfork and the occasional dousing from a garden hose.

Bins really help with the aesthetics, though, and may be called for to keep critters out if you're going to be recycling a lot of grain-based food (bread, rice, etc).

And if family members are really worried about smell (and you're really committed to composting food, which is more complicated than straight-up yard waste), I've heard great things about NatureMill composters. Bokashi composters are cheaper initially, but require buying more stuff along the line.
posted by joyceanmachine at 11:32 AM on May 16

hehehe, at first glance I read the post as " I want to start COMPOSING...."

Google it. Tons of resources online regarding this. Lots of different ways of going about it so you do have a bit of reading to do before deciding which method is best for your situation.
You can do stuff as simple as building a box with 3 old pallets and putting leaves and grass clippings and organic food stuffs in. Coffee grinds too.

Good luck. Report back your success!
posted by a3matrix at 11:42 AM on May 16

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.
posted by MrMoonPie at 11:44 AM on May 16

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.
posted by advicepig at 11:47 AM on May 16 [1 favorite]

This gives an overview.

in a backyard
posted by nikksioux at 11:48 AM on May 16

nikksioux, that backyard link says don't put cooked foods, rice, or pasta in the pile. I've put all those in mine, regularly, with no problems (that I'm aware of, anyway). Anyone know the deal on that?
posted by MrMoonPie at 12:05 PM on May 16

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.
posted by weapons-grade pandemonium at 12:16 PM on May 16

If space isn't a problem, I recommend my stupidly-easy composting technique, requiring only a small container, and a shovel.

Reserve a long (say 20'), narrow (about 2') strip of ground for composting. Put your plant-based food scraps in a gallon-size sealable container in your kitchen. When it approaches full, bury the contents in a shallow grave -- just put it in a small hole with a couple of shovels full of dirt on top. Next time, move one spot over. In a few months, you can start over in the first spot -- there'll be nothing there but dirt and fat, happy worms (and maybe some really hard things like walnut shells -- you can tune this by leaving those things out.) Eventually there'll be enough excess dirt that you'll need to remove some (and it'll be very high-quality soil for growing things.)

Here in the Bay Area, I've had raccoons dig things up a couple of times (in years of doing it) but no rodent issues (and I've never smelled anything.)

This isn't extensible to dealing with a lot of yard waste, though.
posted by Zed_Lopez at 12:30 PM on May 16

I have a commercial bin, basically 4 snap-together sides (with access panels on the bottom) and a spring-loaded top, that sits on bare ground. So far, no vermin, and the dogs can't get in it. There's really only a sad small pile of stuff on the ground inside it, but I wanted a large container so that leaves could go in when the time is right.
posted by Lyn Never at 12:44 PM on May 16

It's all pretty much covered here. I agree that you should get a container. I have one similar to this. It has four stackable sections, which is very convenient. As the materials break down, they reduce in volume. It's much easier to remove the finished compost if you can remove the top couple stacks.

One thing not mentioned here yet: There's 'hot' composting and 'cold' composting. Cold composting is basically just piling stuff up and leaving it to decompose in its own time. Takes a long time and is very dull.

Hot composting involves little microorganisms who are so incredibly excited about their job that they heat the pile up to 130 or 140 degrees, which a) makes stuff decompose faster and b) kills weed seeds, diseases that might be presents in veggie/fruit plants you added to the pile, and other microbes that could be harmful. A hot compost pile can go from leaves/scraps to finished compost in as little as 3-4 weeks. To get a pile hot, you need to attract the right bacteria. There are commercial compost starters you can buy. They work, but they can be pricey. Another thing that works well is manure. I have chickens, so I toss chicken poop into my pile. It heats up in a day or two. If you have neighbors with chickens (or horses), they'll probably happily supply you. Note that different kinds of manure have different nitrogen levels.

The fundamental rule of composting is that you want to get the right ratio of brown + green + water. Brown is carbon (leaves, usually), green is nitrogen (grass clippings, food scraps, manure). Some people say you want 30:1 brown to green, others say 60:1. Basically, you want a lot more brown than green. If your pile begins to smell like ammonia, you have too much nitrogen (green). One thing caddis said upthread confuses me: As for leaves, leave out the brown leaves in the fall. Not really sure what he means. But brown fall leaves are fine and dandy.

Moisture: The rule of thumb is that your compost should be about as wet as a "damp sponge." It's hard to compare leaves to sponges, but the metric has always worked for me. Too much water is bad. Not enough water is bad. The right amount of water is good.

Turn your pile every week or so to aerate it. This mixes stuff up, distributes it around, and gives the aerobic bacteria a breath of fresh air.

A note to your family: If your pile starts to smell like ANYTHING, you're doing something wrong. A healthy compost pile should smell like the forest floor (with little nymphs and sprites and stuff!).

Okay. Now, when you've mastered compost, your next assignment will be making compost tea. I swear, it's like fucking steroids for plants.
posted by mudpuppie at 12:46 PM on May 16 [4 favorites]

Hey, check it out. If you're really in Cambridge, like your profile says, you can buy a bin from the city. They probably have composting classes, too. A lot of cities do. I know Boston does. Call the Recycling department and check it out!
posted by mudpuppie at 12:51 PM on May 16

Seconding buying the bin from the City of Cambridge. I did that last fall, and it's worked out great! They even give you a bonus kitchen bin.
posted by wyzewoman at 1:32 PM on May 16

As for leaves, leave out the brown leaves in the fall. They are a special composting project and will slow down a regular pile.

Not true. Carboniferous material (dry leaves, chopped straw "brown" stuff) is needed because the microorganisms that break compost down need carbon as well as nitrogen (it's what they eat, and the products they produce are water, carbon dioxide, heat, and humus). Without carbon, the chemical processes that make up these products can't happen. A 30:1 carbon to nitrogen ratio in your starting pile will give you about 8:1 finished compost, because 2/3 of the carbon is released to the atomsphere, and the rest is building blocks for nutrients your plants need. (8:1 is the target, because it's the ratio at which natural soil systems operate.) It's also important to have brown waste to maintain good texture: if it's all wet, heavy, nitrogenous material, the microorganisms will not be able to get oxygen, and your pile will go anaerobic. Anaerobic decompostion is not only extra stinky, but it's products are mostly organic acids, which can be toxic to plants; and gaseous forms of nitrogen, which is lost to the atmosphere. It's good to have some brown stuff saved up to toss in with your green waste. About 2:1 brown to green is an easy in-the-field estimate that usually works. Avoid composting really heavily carboniferous material like lots of cardboard or newspaper- since the organisms that break the stuff down need a certain amount of nitrogen for the amount of carbon, your pile can become nitrogen deficient.

Optimum pile size is 4x4'. I like to have mine on the ground, because you have an instant source of all kinds of composters from worms and bugs to bacteria and fungi. Otherwise mudpuppie has pretty much said it all.
posted by oneirodynia at 1:40 PM on May 16 [1 favorite]

nikksioux, that backyard link says don't put cooked foods, rice, or pasta in the pile. I've put all those in mine, regularly, with no problems (that I'm aware of, anyway). Anyone know the deal on that?

The general wisdom is that those things are stinky, and attract pests. Fatty stuff is slow to decompose.
posted by oneirodynia at 1:51 PM on May 16

Higher nitrogen to carbon ratios make for faster composting, especially for someone just starting out. A high percentage of grass clippings will give you a hot pile with rich compost in weeks. It does take a little more effort to stay with the turning, but the quick results are gratifying to a first timer. (by the way, grass is filled with carbon, it just has a high nitrogen content). A hot pile also kills weed seeds. Anyway, an all grass pile would be too wet and sticky. I am just advocating a high nitrogen pile. You still need browns and stuff for texture and balance. Compost made in a high nitrogen pile is quick, strong like fertilizer and a tea made from such compost is especially nourishing. A tumbler, like this, makes it easy and this one even makes tea for you.
posted by caddis at 2:17 PM on May 16

Pardon a self-link, but it happens that I just posted a short podcast about starting a cheap worm bin for indoor vermicomposting.
posted by itstheclamsname at 2:31 PM on May 16

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 compost should take about two weeks; and reach up to , but not over, 160F. Temperatures higher than that kill the bacteria, and can make the compost sterile, reducing it's pathogen fighting properties. composting relies on well documented, specific processes that require a certain amount of time as the successive stages of different types of microorganisms go through their life cycle in the compost. If you rush it, you miss out on the stages that produce well finished, properly cured, nitrogen rich compost.
posted by oneirodynia at 2:56 PM on May 16 [1 favorite]

if you want easy, Zed_lopez's "shallow grave" method works. I discovered that myself last year. You are basically doing worm composting - only using generic earthworms, instead of the specialized red wiggler worms. It's also surprisingly fast how quickly veggie scraps get broken down. Just bury some scraps and soak the ground. A piece of cardboard on top keeps the soil moist.

I've tried the plastic composting bins, and I've concluded that they are expensive, ugly and crack in half after about a year. They are also open to the ground, and as mentioned, are an ideal rat's nest. (A huge grey norwegian jumped out of mine while I was turning the pile.) If you go with a composting bin, it can be as simple as a wooden box. Just make sure that it is completely contained and that raccoons, rats, squirrels, etc. can't get into it.
posted by kamelhoecker at 4:06 PM on May 16

Of the several composting methods and doohickeys I've tried for composting kitchen scraps, I like the Green Cone the best. (I got mine from my local county government, cheap.) Since the above-ground part is fully enclosed, it's very neat and there are no smells. I especially like this because I am a very lazy composter and cannot be bothered to balance the greens and browns that go into the bin.

To keep the varmints from getting in, we lined the below-ground basket with hardware cloth, then surrounded the bins with rocks at the surface. I haven't seen any sign of rodent intrusion in the three or so years we've had them going.
posted by sculpin at 5:35 PM on May 16

Mr. Moon Pie:

I've also put those things in mine (everything except meat and dairy) and it really does make a difference in the smell and attraction to pests (per oneirodynia's response) I think that part just goes to personal preference.
posted by nikksioux at 5:36 PM on May 16

Worms are good. They know what they're doing. Every now and then you trick them up into the top so you can take what is now kick ass soil from the bottom and then they'll make you some more.
posted by mu~ha~ha~ha~har at 7:31 PM on May 16

i would go look at what folks in your area are doing. cambridge, MA? visit a local community garden. the victory gardens in the fens have all sorts of interesting small scale systems happening. or do a volunteer day with a group like the food project, and you can bombard them with questions. freezing temperatures, for instance, vexed me when i lived there for a year and started a pile.

people can be quite, what's the word, attached, to their personal style of composting. but it really depends on what you are trying to accomplish. need high quality soil supplements in a timely manner? you need a hot pile, nutrient ratios, and it wouldn't hurt to mix in some manure. just want to divert food scraps from the landfill? pretty much any system will do, and you can keep it from smelling if you get the moist/dry level pretty balanced and filter out animal products. want to surprise yourself with the depth of your appreciation for worms? etc

i agree with kamelhoecker that the plastic composting bins are pre-garbage. it's hard to aerate the pile in them and they crack. they present well, though. i always found that having a bale of straw around to top off a chicken wire ring pile would do wonders for presentation.
posted by ioesf at 12:06 AM on May 17