Compost is created in forests, fields, and plains around the world. It is the result of organic matter (plant parts and food scraps) decomposing with the aid of water, oxygen, invertebrate organisms (worms, slugs, sow bugs), and beneficial microorganisms (fungi and bacteria). Crumbly, dark brown finished compost is not soil, though it may resemble it; nor is it fertilizer. It is a soil amendment that can be incorporated into garden soil to help it retain moisture and nutrients. It improves the texture of problem soils and encourages the growth of microorganisms that maintain plant and soil health. Perhaps best of all, it's a free and easy way to dispose of organic waste, which decreases trash pickups and landfill usage. And getting started doesn't necessarily require any special equipment: piling up materials and letting nature take its course will eventually produce compost. By following a few simple guidelines and building or buying a compost bin, however, you can optimize the process, making it happen more quickly and conveniently.

This three-bin setup is the classic, DIY backyard composting system. It is the best choice for large families, rural properties, and avid gardeners because it has one pile to add to, one pile that is decomposing, and one finished pile to use in the garden. For instructions on building your own, go to extension.iastate.edu/Publications/PM683.pdf

Successful composting depends on the right combination of "green" and "brown" material. The greens (food scraps, lawn cuttings) provide nitrogen, while the browns (dry leaves, newspaper, hay) provide carbon. To create optimal conditions for decomposition, you'll need twice as much brown material as green. These photos show how to construct the pile and which materials are appropriate.

Newspaper and hay make good brown matter when dry leaves are in short supply. Shred newspaper so it doesn't form a mat. Do not compost glossy or colored paper.

A handful (or shovelful, depending on the size of your bin) of garden soil in the middle of the pile helps to inoculate it with the microorganisms that are necessary for decomposition.

Flowers, leaves, grass clippings, and weeds are great candidates for the compost pile. Do not compost weeds bearing seeds, or diseased or pest-ridden foliage.

Autumn leaves are the cheapest, most plentiful form of carbon for composting. Since they're abundant only briefly, many composters stockpile them to use through winter.

Starting from scratch means you can get it right from the beginning. If you've already begun, adapt these instructions to produce peerless compost.

1. Site Your Bin
Proper siting means easier management. Full sun necessitates frequent watering; full shade slows decomposition. The bin should be convenient to a water source.

2. Start with Brown
Begin your pile with an airy carbon layer, ideally a loose pile of fallen leaves.

3. Add Green
Aim for half as much green as brown. Too much green can lead to malodorous, slimy conditions.

4. Spring In Some Soil
A scoop of soil in the pile encourages microorganisms. Some experts recommend adding fertilizer, too, but a well-built pile will have enough nitrogen without it.

5. Repeat Brown and Green Layer
Continue layering browns and greens in a 2-to-1 ratio, ending with a layer of brown. Small pieces decompose faster, so consider cutting down any large ones.

6. Keep It Moist
Your pile should be as wet as a wrung-out sponge: moist but not drippy. Check often, and water as needed. On an open pile, use a tarp to hold in moisture or keep out rain.

7. Take A Turn
After a week, you'll notice the pile start to heat up. Now is a good time to turn it with a pitchfork, mixing the layers. Turning provides oxygen for the microorganisms and facilitates rapid, even decomposition.

8. Keep Turning
Turn the pile weekly when it's warm out. In winter, the pile may freeze and the process will slow dramatically.

9. Harvest the Compost
Depending on ingredients and conditions, your compost will be done two months to a year after you start the pile. Frequent turning expedites the process.

When compost is ready for use, it will be dark brown, free of recognizable ingredients, and inoffensive to smell. Its nutrient content will vary depending on the materials that went into it. Finished compost can be used as mulch or top dressing, dug into any problematic soil, or raked directly onto the lawn.

Building a composter is always an option (see extension.iastate.edu/Publications/PM683.pdf). But there are a number of good ready-made models on the market. Many are suitable for small spaces or urban gardens, since they are compact and can be sealed to keep out rodents or other pests. The closed environment makes it easier to maintain optimum moisture levels, especially in extreme climates. Here are the pros and cons of three popular models.

PROS: It swings on an axis, so it's a cinch to aerate.

CONS: When full, it can be heavy and unbalanced. Also, once full, nothing can be added until the contents have fully composted. 52-gallon recycled plastic tumbler (similar to shown),compostbins.com.

PROS: The door at the base lets you remove finished compost while continuing to add fresh materials at the top.

CONS: You've got to reach inside with a pitchfork to turn the materials, which can be a tricky maneuver. 86-gallon recycled plastic bin,compostbins.com.

PROS: This space-saver sits on a base with embedded rollers, making it easy to rotate without reaching inside.

CONS: Like the tumbler, its contents must be left to decompose before more material can be added. 52-gallon compost tumbler, compostbins.com.

An infusion of finished compost and water, compost tea is easy to make at home with a few basic supplies or with one of the commercially available brewing systems on the market. There are competing claims, however, as to what compost tea can do. Supporters say aerating compost tea with a simple aquarium pump results in a brew that can combat plant disease. But studies for disease control have produced contradictory results, causing many scientists to reject such claims. What's not debated is its use as an effective liquid fertilizer. Here's how to brew your own.