Oil isn't black gold. Compost is.
It improves just about any soil you add it to, makes plants healthier, discourages pathogens in the soil, moderates swings in soil temperature/pH/moisture, prevents erosion and water runoff, reduces the need for chemical fertilizers, prolongs the availability of whatever fertilizers you do use, and reverses male pattern baldness. OK, that last one isn't true. I think.
Unfortunately buying finished compost at your local big box store or garden center gets expensive, and occasionally the quality of the stuff can be underwhelming. So you want to start making compost instead of buying it, but you're worried that it'll be too much trouble, huh? Cheer up! Composting doesn't have to be complicated, scientifically rigorous, or closely monitored. It isn't guaranteed to be messy and smelly. You don't have to primp and fuss over a compost pile if you don't want to. Most of the in-depth discussion among us composting nerds is geared toward getting finished compost as fast as possible. You don't have to do things my way or anybody else's way. Take whatever raw materials you have, put 'em in contact with the soil, cover 'em, and you'll get compost soon enough.
Just about anything that used to be alive -- or that's made from something that used to be alive -- will rot eventually. It's really that simple.
----- Begin compost geekery -----
If you absolutely need to make good compost as fast as you can, then you want a hot pile (or bin). That'll require the right ratio of carbon and nitrogen in your finely-chopped or -shredded raw materials, the right amounts of oxygen and water, and a big enough pile to generate and retain the heat that kills pathogens and weed seeds.
The ratio of C:N (a.k.a. "browns and greens") should be roughly 30:1 by weight. The list of raw materials and the compost mix calculator below will help you figure out the C:N ratio of your own refuse. If the carbon side of the ratio gets too high, the pile won't cook. If the nitrogen side of the ratio gets too high, the pile will get ridiculously hot, and too much of that valuable nitrogen will leave the pile in the form of disgustingly stinky ammonia gas.
To keep the pile aerated properly, you can either flip the materials over periodically, use a compost aerator tool, build the pile with some perforated pipes running into it, or leave enough sticks and coarse material mixed in that you get air pockets. If you get a big pile going, but neglect to aerate it enough, it'll go anaerobic. That means that bacteria that live in low-oxygen environments will crowd out the others, which is not fun for your neighbors. Anaerobic decomposition just plain reeks. Think "swamp." If you go too crazy with aerating your pile, you'll let too much heat escape into the air and your pile won't kill pathogens and weed seeds as effectively.
The ideal moisture content is much like a lightly wrung out sponge. Without water, decomposition slows to a crawl. With too much water you'll get a cold, wet, stinky, anaerobic mess.
To retain enough heat to get the aerobic bacteria working at peak efficiency, your pile will need to measure at least 4x4x4 feet. You can get compost to cook in smaller piles, but it'll require insulation and a lot more attention. If you build an uninsulated pile that's smaller than about 20 cubic feet, you're going to have a really hard time getting it to heat up.
The rule of thumb for a hot pile is "shoot for a steady temperature above ~130F." It'll take a perfect new pile a few days to get there, and it won't stay that hot forever, but that's the magic temperature for hot composting. The pile will shrink as the raw materials decompose, and the temperature will begin to tail off after a day or so at peak heat. When things begin to cool off, just aerate the pile, mix the raw materials on the edges into the core, re-moisten if needed, and let it heat up again.
I've been able to get a big pile to heat up three times, but that's about all I can expect. A different bunch of bacteria, plus fungi, insects, and worms will take over when the pile cools a bit, and they'll continue breaking things down. Eventually you'll be left with crumbly black gold. Depending on how intently you babysit your pile, you can get finished compost in a couple of weeks.
----- End compost geekery -----
You DON'T have to do it that way! If you're willing to be patient, you can get compost without going to the trouble of building a hot pile.
For example, I have a Biostack bin that I use for hot composting a very wide variety of organic matter and rock dust; its finished compost goes onto my veggie garden. However, I also have a big, mostly-neglected cold pile that generates compost for my ornamental plants and my lawn. I start a new cold pile in the middle of summer with bags of shredded office paper and junk mail, bags of grass clippings, bags of fallen leaves from the year before, uprooted weeds that haven't yet gone to seed, wood ashes from my fireplace, used potting mix, shredded trimmings from bushes and trees that have just been pruned, whatever nasty hunks of clay I've got left over from that year's planting holes, and a handful of finished compost. It all goes in a big ol' pile that's about 4x3x12, after which it gets watered, and then it gets left. For a year. It takes awhile, and weeds tend to grow on top, but it eventually shrinks down to pretty decent compost. It almost never gets hot enough to kill every last weed seed, but I don't care. In early summer when it's almost done, I flip it once. That puts the weeds growing on top down inside the pile, and exposes any viable seeds to the air so they can germinate. Those weeds get plucked as they sprout, and about two weeks later I've got decent (if a bit chunky) compost. I've actually started growing cover crops on top of my cold pile to crowd out opportunistic weeds, provide "green manure," and prevent nutrients from leaching away in the rain and snow. So far buckwheat and clover make a good mix.
There are a million other ways to compost. You can use worms. You can use the Bokashi method, which intentionally uses anaerobic bacteria in a sealed container to ferment kitchen scraps into compost. You can spot compost, which involves burying small amounts of raw materials wherever the soil needs improving. Trench composting is spot composting on a larger scale. Some people make biochar, which involves making charcoal, soaking it in compost tea or fish emulsion, drying it, crushing it, then incorporating the powdered charcoal into the soil. Farmers near my home compost giant piles of sawdust from their stables that's mixed with the manure of their alpacas, horses, or goats. Soiled straw bedding from rabbit hutches and chicken coops can really heat up if left in a pile. Other people do sheet composting, where mats of grass clippings and shredded leaves form a mulch that slowly decomposes in place. If you can't make enough compost to meet your needs, you can stretch what you've got by making compost tea and watering your plants with it. A few brave souls even compost otherwise dangerous stuff like roadkill, pet poop, grease, and whatever else falls into their clutches ... but their methods are not for the faint of heart (or stomach). There is no "right way" to compost.
Enough bloviating from me. I'll wrap things up with a few links, which I'll add to as needed:
8 steps to smart gardening:
http://www.hgtv.com/landscapin...
General tips:
http://www.youtube.com/user/pa...
A quick & dirty (soil-y?) handbook for home composting:
http://www.cals.uidaho.edu/edC...
"Can I compost this?":
http://www.compostthis.co.uk/
No-frills composting:
http://www.hgtv.com/landscapin...
Cover crop usage:
http://www.seedsofchange.com/e...
Cover crop guide:
http://www.hort.cornell.edu/bj...
List of raw materials:
http://compost.css.cornell.edu...
Compost mix calculator:
http://www.klickitatcounty.org...
Cornell University's in-depth composting handbook:
http://compost.css.cornell.edu...
Do-It-Yourself compost projects:
http://www.instructables.com/t...
How to build new topsoil:
http://managingwholes.com/new-...
The soil food web:
http://oregonfoodweb.com/
Surprising facts about weeds:
http://journeytoforever.org/fa...
Your turn!
