Friday, June 20, 2008

Compost your organic waste

Reduce waste by composting

If you have a yard that generates most any kind of green waste, you probably have the right ingredients and enough room to set up your own compost bin.

Composting is easy and cheap, you can cut down your garbage by hundreds of pounds each year, and create a mixture that can be used to improve the soil.

You could be growing instead of throwing

Home composting is a way for you to speed up the natural process of decomposition and return organic materials to the soil. Yard trimmings and food scraps make up nearly 1/6 of what the average household throws into the garbage.

Why throw this stuff away when it can be put to good use in your yard and garden?

By composting, you can convert organic wastes — yard trimmings, leaves and many kinds of kitchen scraps — into a dark, crumbly mixture that can be used to improve the soil and reduce your use of fertilizer and water.

In Minnesota, yard and tree wastes have been banned from garbage since 1992. Don't trash it!
Don't trash it!

Composting Biology 101: The simple science

Composting is a natural process. You don't need fancy equipment or expensive artificial additives to break down your organic scraps and turn them into something useful. Take a moment to learn about what makes composting work.

Guess who's coming to dinner
Check out who the real compost workers are

Composting is done by a wide variety of organisms that are found naturally in organic matter. They work together, feeding on your pile (and each other), to break materials down.Composters

  • Bacteria perform the primary breakdown of organic materials. Bacteria aren't added to your compost pile — they're found in almost all forms of organic matter. There are several different types, and they will flourish and reproduce rapidly under the proper conditions.

  • Nonbacterial composters — fungi, worms, and a variety of inveratebrates — go to work on your pile. Some feed directly on plant tissues, helping bacteria in their role Squirmy wormsof primary decomposers, while others will actually eat the bacteria. Bugs like centipedes and beetles will feed on the smaller invertebrates.

What's compostable? (and what isn't?)
Learning the basics: "Green" and "Brown"

Like any simple recipe, you'll get the best results if you use the right mix of ingredients to make your compost. The key materials are nitrogren-rich "greens," carbon-rich "browns," water, and air. All of these are essential, but they're easy to mix together for quality compost.

Greens provide nitrogen, and act as a source of protein for the microbes that are hard at work in your compost pile.
  • Green leaves
  • Coffee grounds
  • Tea bags
  • Plant trimmings
  • Raw fruit and vegetable scraps
  • Fresh grass clippings
  • Hair
Browns are a source of carbon, and provide energy for the microbes.
  • Dried grasses, leaves and some weeds
  • Straw
  • Woodchips
  • Twigs and branches
  • Sawdust
  • Shredded newspaper
  • Corncobs and stalks

As living things, the microbes in your compost pile need water and air to work and live. Water allows microbes to grow and travel around in the pile to decompose materials. Turning your pile each week with a spade or pitchfork will provide air to aid decomposition and control odors.

  • Food with meat, dairy or oils
  • Pet feces (dog, cat or bird)
  • Diseased plants
  • Weeds gone to seed
  • Ash from charcoal or coal

Just say no. While many materials can be composted, there are some items that you should keep out of your home compost pile. Excluding foods with meat, dairy or oils will minimize odors and keep your pile from attracting scavengers like dogs and raccoons. Since compost is generally used for a soil amendment, you want to keep it free of plant diseases and unhealthy bacteria.

Want to get started? Let's break it down!

Getting your own compost bin started can be boiled down to three simple steps: Make a compost bin or buy one, throw in your kitchen scraps and yard waste, and mix it up with a shovel or pitchfork once in a while.

1. Begin with the bin

    Pallet compost bin

    Inexpensive materials like pallets, snow fence or chicken wire can be used to make simple compost enclosures.

    Wire compost bin.

    Location, location, location. Pick a spot in your yard that's at least partially shaded and at least 2 feet from a structure like your house or a fence. Other considerations:

    • Convenient for you to add materials
    • Access to water
    • Good drainage

    Containers. You can compost in a simple pile, but using a container or bin helps your compost pile retain heat and moisture and look neat. To get started, it's easy to go with a single bin system. As materials are added and mixed together, the finished compost settles to the bottom of the bin.

    Materials. Bins can be built from scrap lumber, old pallets, snow fence, chicken wire, or concrete blocks. Typically, several types of composting bins are sold at hardware or lawn and garden stores.

    Size. A pile that is 1 cubic yard (3 feet high, 3 feet wide, 3 feet long) is big enough to retain heat and moisture, but small enough be easily turned. Home compost piles shouldn't be larger than 5' x 5' x 5'.

2. Add the first materials

    If you're just starting a compost pile, you can measure out greens and browns to create a good mix of materials — for example, an equal mixture of brown autumn leaves and fresh grass clippings will give you an optimal composting combination. But new composters shouldn't worry about getting the right mix; it's very easy to add new materials that will adjust the pile's performance.

    1. Lay a base. Start with a layer of browns, laying down 4-6 inches of twigs or other coarse carbons on the bottom of the pile for good air circulation.
    2. Alternate greens and browns. Add layers of nitrogen and carbon materials. Make layers about 4-6 inches thick. Once you turn the pile the first time, these materials will get mixed together and compost more efficiently.
    3. Size does matter. Most materials will decompose faster if they are broken or chopped into smaller pieces, as it makes more surface area available to your composters and water.
    4. Water as you go. Your compost pile should be moist, kind of like a wrung-out sponge. Squeeze a handful of compost; if small beads of water appear between your fingers, you have enough water. Your pile will get water from rain, as well as the moisture in the greens — for example, fresh grass clippings are nearly 80% water by weight. If the pile gets too wet, you can turn it more frequently to dry it, or add more dry brown materials to soak up the excess moisture.

3. Mix up the pile: As the compost turns

Turn your compost

Turning your pile with a pitchfork or shovel mixes up the greens and browns, brings oxygen into the pile, and helps break up materials into smaller bits.

    Once you build your pile, the real composters get to work — bacteria, fungi and insects help break down the materials in your compost bin. As the organic materials decompose, your pile will get hot on the inside and you might see some steam. In about a week, your compost will be ready for turning.

    Use a pitchfork or shovel to mix up the layers of green and brown and move materials toward the center of the pile. You can empty your bin and re-layer, or just work materials around inside the bin. Break up clumps of material and wet the pile as needed.

    Repeat until it's complete. The composting process can be pretty quick in the summer months. Your compost pile may no longer heat up after just a few weeks. Look in your pile for finished compost — material that is dark and crumbly, fresh-smelling, and no longer looks like what you originally put into your bin.

Using finished compost

Your compost can really pay off in the yard or garden. While compost is not a fertilizer, it can contain nutrients which improve plant growth. By using compost, you can improve the soil and reduce your use of fertilizer and water.

You'll learn why gardeners call compost "black gold."

  • Mix in compost to improve soil. In sandy soils, compost acts like a sponge, reFinished composttaining water and nutrients where it can be reached by plant roots. In clay soils, compost makes the ground more porous, creating tiny holes and passageways that help soil drain more quickly.
  • Spread compost on your lawn to help fill in low spots.
  • Use as a mulch for landscaping and garden plants. Mulches cover the soil around plants, protecting the soil from erosion and the drying effects of wind and sun.
  • Mix compost into pots for potted plants.

Common problems and solutions

Home composting isn't very complicated, but the typical composter will likely run into one or more of these common challenges.

The pile doesn't heat up.

"Recycle" yard and food wastes

Composting is a way to recycle yard and food wastes back into the soil.

  • Size matters: A pile that's at least 3 feet wide and tall will help "hot" composting by conserving heat and moisture.
  • Moisture. Try the squeeze test: Pick up a handful of compostable material, make a fist and squeeze it in your hand. If you do not see beads of water between your fingers the pile is too dry. Turn the pile and water thoroughly with a hose.
  • Nitrogen: If the pile is new, you may need to add more "green" to your pile. Try grass clippings or fruit and vegetable scraps. In a pinch, use a scoop of nitrogen-rich plant fertilizer.
  • Aerate: A compost pile needs to breathe to function efficiently. Use coarse materials such as wood chips to create air spaces in the pile and add carbon to the mix.
  • Maybe it's done: If your pile is old, and you've turned it a few times, you may already have finished compost. Use a screen to sift off bigger pieces and use the compost in your garden or on your lawn.
There's an odor: Methinks your compost stinks.
  • Rotten egg smell: Your pile may not be getting enough air because it's too wet. Turn the pile with a shovel or pitchfork to let in air and mix things up. Wood chips or some other bulking agent could be added to increase air flow.
  • Rotten egg smell, part 2: If your compost pile is too compacted it won't get good air flow. Again, turn pile to fluff up the contents and create air pockets. If particle size is small, under one inch, add a bulking agent such as wood chips that are around 2 inches.
  • Ammonia odors often indicate too much "green." Add more carbon materials: dead leaves, non-recyclable paper, or straw. Mix the pile thoroughly and see that the moisture content passes the squeeze test.

The pile is attracting scavengers and insect pests.

  • Nonfat diet: No food wastes with oils, meats, or dairy; odors from these can attract scavengers like raccoons or mice.
  • Keep it covered: Keep new food wastes covered with materials high in carbon and in the middle of the pile. Covering the bin will help keep out larger pests.
  • Insects are a normal part of composting, but an active pile will create enough heat to kill their eggs and reduce the nuisance insects.

Links to resources

There are a lot of terrific online resources that you can access for more information.

Online tutorials

Videos for loan

The Education Clearinghouse at the Minnesota Office of Environmental Assistance offers a lending library of educational videos to Minnesota residents. Videos are offered for a free two-week loan (the borrower pays for return shipping.) Call the Clearinghouse at 651-215-0232 or 800-877-6300 toll-free, or e-mail them at

  • Compost: Truth or Consequences (15 minutes)
    Designed to take the mystery out of home composting, this video teaches how to create the right conditions for quality compost, avoiding odors and getting a "hot" pile that decomposes rapidly.
  • Home Composting: Turning Your Spoils to Soils (17 minutes)
    This video describes how easy it is to start a compost pile at home for yard and kitchen waste, as well as explaining the benefits of mulches and leaving grass clippings on the lawn.
  • It's Gotten Rotten (20 minutes)
    The science of composting literally goes under the microscope in this video, with amazing up-close photography. A high school science lab provides the set for applying biology, life and physical sciences to understand how the composting process breaks down organic matter and turns it into a useful soil amendment. Includes a reference copy of "Composting in the Classroom," a comprehensive teacher's guide with research projects for high school students.

Manufacturers of compost bins

    If you don't want to make your own bin, check out this site's extensive listing of commercially made bins and accessories from national manufacturers.

National organizations