A black plastic composting barrel sits beside a shrub next to a fence.

A collection of earthworms wriggles on a manŐs hand.

Community gardeners prepare a bed for planting.

Two rows of seedlings in a field are showered by an irrigation system.

Composting 101

Composting involves the decomposition of organic matter, such as plants and once-living household waste. Millions of microscopic organisms, including bacteria and fungi, consume and recycle this waste to produce a dark, crumbly soil that is called compost. This process occurs in nature every day — vegetation naturally decays, and plants, animals, and microorganisms use it produce nutrient-rich dirt. Instead of filling landfills with organic waste, we can compost in our own outdoor piles or indoor bins. The resulting soil can be added to enrich yards, houseplants, and gardens.

But let’s face it: Keeping garbage around essentially rotting in our midst runs counter to everything we’ve internalized about hygiene and cleanliness. But fear not; your house need not smell like the town dump, and a small change to your routine (you already sort your recycling of course, right?) can not only shrink your footprint on the planet, but actively contribute to the restoration of the ecological lifecycle.

Compost benefits the Earth in many ways, from remediating contaminated soils and facilitating reforestation to reducing dependence on chemical fertilizers and removing pollutants from the air and water. When we compost, we merely accelerate a natural biological process.

The Right Stuff

Several factors must be present in a compost pile or bin in order for decomposition to occur. Microorganisms need water to survive and to access the substances in the compost pile — but not too much water. They also need adequate oxygen and a balance of nitrogen and carbon. Nitrogen is found in “green” materials like grass clippings and food scraps — which also naturally keep the compost pile moist — while carbon is contained in “brown” materials like shredded newspaper, dry leaves, and branches. To keep it simple, just remember: Air, Water, Greens, and Browns.

As the microorganisms in the pile or bin eat, they generate heat, raising the temperature of the pile and increasing the rate of anaerobic activity, or decomposition. Compost piles that are functioning optimally will have a temperature range of 140 to 160 degrees Fahrenheit. When organic materials heat up and decompose, they shrink — up to 70 percent of their original size. The composted materials produced will contain a dark-brown or black “humus” that smells earthy and like dirt. If you want your compost pile to heat up, it should be at least 3'x3'. You can have a fine compost pile that doesn't get that hot, it will just take a little longer to compost, and won't kill weed seeds.

Do It Yourself

First, choose the type of compost container and location you’d like to use. If you have the space to compost outdoors, you can build or purchase a compost bin, or simply go binless and build your pile on the ground — a minimum of three feet high by three feet wide is best. In an outdoor bin, greens like food scraps are combined with browns like dead plants and dried leaves. Composting will be quicker if the pile is aerated, monitored for sufficient moisture, and turned regularly.

Materials like bricks, buckets, wood, and chicken wire are commonly used to build bins. Rotating bins, or a series of bins, allow the compost to be turned on a regular basis, thus speeding up the process. Holding compost units, meant for smaller volumes of yard waste, do not require turning, but the process is slower.

If you don’t have available outdoor space, composting can be done indoors — in even the smallest of apartments. You can compost materials indoors with an indoor bin, which can be made or purchased or with a small amount of red worms, or red wigglers, which can eat vegetable and fruit scraps and other organic kitchen waste and recycle it into compost. Vermicomposting worm bins are usually made out of plastic or wood, with a tight lid and air holes. Damp shredded newspaper provides the carbon-rich bedding. About one-square foot of composting area is needed to compost one pound of food per week.

How to build outdoor, indoor, and worm compost bins

Building your own indoor bin (scroll down to “Indoor Composting”)

Learn about vermicomposting

Make your own worm bin

Getting Started

Begin with a six-inch layer of brown materials in an outdoor pile or bin. (For an indoor bin you’ll want to use a lesser amount of damp, shredded newspaper.) Add a smaller layer of green materials, plus a handful of finished compost or soil. Mix the two layers lightly and top it with a layer of brown materials. Add water until moist, and turn the pile every one or two weeks, making sure it doesn’t dry out. Compost will be ready in one to four months.

Alternately, add brown and green materials as you go, making sure to moisten dry materials. When the bin is full or the pile is at least three feet high, mix grass clippings and other green waste into the compost, making sure that food waste is buried. The pile can be covered with a tarp to ensure it doesn’t get too dry. Compost is ready to use when the material at the bottom is dark and earthy-smelling, anytime between two months to two years.

Compost Tips

Don’t compost animal products like meat and dairy, fatty scraps, or pet droppings. These can attract pests like flies and rodents to your compost pile and spread odor problems and disease.

A common mistake is to have too many "greens" in your compost. Too many food scraps and fresh plant material can make your compost stink. Remedy by adding more "browns," like dried leaves or straw, or sprinkle a thin layer of chemical-free sawdust after each layer of kitchen scraps.

Don’t squash the materials you add to your compost pile, but make sure they have room to breathe.

Shred, slice, or cut scraps into smaller pieces to ensure quicker decomposition.

Finished compost will look and smell like rich, dark dirt. You should not be able to recognize the original materials.

Find more composting resources >>

Learn about the making of DIRT! The Movie >>


Home | The Film | Composting 101 | Behind the Scenes | Get Involved | Talkback | Film Credits | Get the DVD | Site Credits DIRT! The Movie home page Watch Preview