Health Protection

                        F a c t s

Composting

What is Composting?

Composting is a great way to reduce your household waste by up to one-third. It also produces a rich soil conditioner for your garden, lawn and houseplants. Composting takes advantage of a natural process that converts organic material into a soil-like material. Micro organisms, such as bacteria and fungi, do the work by breaking down the organic material into simpler substances.

Compost provides nutrients for plants; it is high in organic content and helps improve the health of soil. Compost is not a fertilizer but it does contain nutrients that improve plants.

The composting process and the time it takes are affected by a number of factors:

• Temperatures reached in compost pile

• Moisture

• Aeration (oxygen in compost pile)

• Outside temperatures

• Carbon-to-nitrogen mix

• Amount of turning

Odour Control

Composting is not an odour-free process, but it can be effectively controlled so odours are minimal and acceptable. Composting is a process that requires oxygen. If the process becomes restricted in oxygen, it can become anaerobic and cause odours.

To prevent odours from developing there are a few things to remember:

1. Do not add large, unchopped items to the pile. Compostable items that are about 2.5 cm (1”) or smaller will break down quickly because they offer more surface area for the decomposer organisms to work on.

2. Make sure each layer of material is no more than 10-15 cm (4-6”) thick. A compost pile consists of layers of browns (carbon sources), such as finished compost, soil or dried leaves, and greens (nitrogen sources), such as food waste and fresh yard waste. These materials must be alternated and added in equal layers.

3. Just a little soil is needed. When adding food waste to the pile, bury it in the centre and cover it with a 2.5 cm (1”) layer of finished compost, soil or dried leaves. This will prevent odours and add helpful microbes to the pile.

4. The amount of water is important. The proper amount of moisture in the pile is important in the control of odour. Too much moisture can create a rotten egg smell. Keep the pile as damp as a well-wrung sponge.

5. Never add meat, bones, dairy products, fats, or oils to your compost pile.
   These materials will smell as they decompose and may also attract unwanted insects and animal pests. The decomposition process slows down because these materials take longer to break down.

6. Make sure there is a lot of air in the pile. A compost pile that does not have enough air is called anaerobic (without air). To prevent an anaerobic compost pile, poke holes through it with a broom or rake handle, a stick, or a commercial aerating tool, or turn it with a garden fork. You can also create an airstack that will regularly allow air into your pile. Place a bundle of sticks about 15 cm (6”) in diameter and tied with rope, or a piece of plastic pipe punctured with small air holes, in the centre of the compost pile.

Common Odours

Ammonia

An ammonia smell means that too much nitrogen-rich material has been added to the pile. Materials that are high in nitrogen content include kitchen food waste and green grass clippings. These are called green materials and they must be balanced with carbon-rich, or brown materials, to properly decompose in a compost pile. Materials high in carbon include brown leaves, dried grass clippings, dried garden plants, and straw.

Always add equal volumes of green and brown materials. Turn and mix the materials in the compost pile, dampen to the wetness of a well-wrung sponge, and top with a 2.5 cm (1”) layer of soil. The soil will trap any remaining ammonia and turn it back into nitrogen.

Rotten Egg

Compost piles that are too wet, or too compacted, will become anaerobic and give off a rotten egg smell. Turn the pile with a garden fork or shovel to allow more air into the pile then mix in dry leaves or a similar dry material to absorb moisture. Repeat these steps for a few days then place a 2.5 cm (1”) layer of soil on top of the pile to introduce more decomposer organisms to the pile and reduce the odour.

Pest-Proofing your Compost Bin

You may not be aware of small critters, such as raccoons, mice, rats, or insects, until you start to compost. Previously unnoticed pests may be looking for a new source of food or a cozy bed in your compost pile. The best solution is prevention. If you compost correctly, your pile will be less attractive to pests. Composting will not encourage pest populations to move into your area, though a neglected pile may attract local populations and make them more visible to you.

Here are some methods to protecting your compost pile.

1. Do not compost any meats, fish, bones, oils, fatty foods, or pet manures because animals may be attracted by the smell.

2. Place materials that are high in carbon (eg. dry leaves or dead plants) at the bottom of the pile and along the inside walls of your compost bin. This will provide good airflow, drainage and odour control. Ensure that each layer remains slightly damp to discourage nesting.

3. Cover any exposed food with a layer of dry leaves, a 2.5 cm (1”) layer of soil, or finished compost, or bury food waste in the centre of the pile. This reduces smells that may attract pests.

4. Turn or poke holes in the pile every week or two. A regularly "disturbed" pile helps deter pests.

5. Harvest finished compost at the bottom of the bin every three to six months. This will discourage pests from nesting in the warm finished compost.

6. Choose a location for your compost bin that has good drainage and at least partial sunlight. This improves the efficiency of your pile. Place your bin at least 20-30 cm (8-12”) from fences, decks and buildings to discourage pests and to improve airflow.

Pests will be less likely to discover your compost if they are not already attracted by other sources. It is a good idea to put your plastic garbage bags into a container at the curb, or do not put them out until the morning of collection. Keep leaves and other materials for your pile in a secure garbage can near the composter. Piles of yard waste can provide a safe, warm place for pests to hide or nest. Food waste for your pile should be kept in a sealed container away from the bin. Note: Sources of fresh water and birdseed also attract pests.

Insects

Flies, wasps, hornets, and bees can be discouraged from invading your compost bin by covering any exposed food with a 2.5 cm (1”) layer of soil or by burying fresh food into the pile. Add air to your compost pile by turning it or create air channels by plunging a broomstick handle into the pile. Keep the pile slightly damp so that it will heat up. Higher temperatures and moisture will kill any fly larvae and discourage bees, wasps and hornets from nesting. If a nest has already been set up in your bin, soak the pile completely and leave it damp until the colony vacates the pile. The pile can also be dismantled after freeze-up in the fall.

Rodents and Other Small Animals

Pest-proofing your bin will prevent any animal from tunnelling up through the bottom, climbing into the bin from the sides or top, or chewing holes in the bin.

• Use hardware cloth to line the bottom and outside walls of your bin. For mice use 0.5 cm (1/4”), 16 gauge and for larger pests use 1 cm (1/2”), 20 gauge. (Hardware cloth is galvanized wire mesh and it is available at most home improvement/hardware stores. Chicken wire does not provide good protection.)
   

• Get a tight fitting lid or modify your existing lid by adding hinges and a latch. You can also stretch a bungee cord or chain across the lid and fasten it to the sides of the bin. A heavy brick or rock will also keep the lid secure. Note: Bungee cords can be dangerous if children are assisting in the maintenance of the composter.
   

• Pile rocks or bricks around the outside bottom edge of your bin to temporarily prevent against some burrowing animals.

Sources:
Toronto Public Health

Composting Council of Canada