| Environmental Columns

Household composting in parallel with organic waste collection

The City of Pointe-Claire has been offering organic waste collection for several years. There is a second alternative, however, in which you can use your organic waste to make your own compost for your garden or vegetable patch: household composting.

What is compost?

Compost is organic matter that has been decomposed by microorganisms in an environment that is aerated by oxygen. Organic matter is any material containing carbon derived from living organisms, such as plants and animals. Food and garden waste as well as material made from plant fibres, such as brown paper, newspaper, paper towels and tissues, are considered organic matter.

Inside a household composter, organic matter is transformed by the activity of decomposing organisms, which is called composting. When oxygen is present, bacteria, fungi, insects and other invertebrates feed on the organic matter and break it down into organic and mineral nutrients that can be absorbed by plants.

The advantages of compost

Using compost in your garden or vegetable patch provides several environmental and economic advantages. Compost enriches the soil and reduces the need for chemicals. Mixed with earth, it provides the soil with several nutrients, such as nitrogen and phosphorus, which are necessary for plant growth. It also provides better soil aeration and helps ward off undesirable insects through its repellent effect. It can also serve as a barrier against weeds when used with mulch. Lastly, it helps retain water in the soil, which reduces the need for watering and regulates the amount of water according to plant needs. By using compost, you therefore not only reduce your water bill, but also your purchases of plant-protection products.

In addition to the benefits for your garden, household composting helps divert materials that generate methane (CH4) and leachate as they decompose from landfills. Methane is a powerful greenhouse gas and leachate is the liquid produced when organic matter decomposes. As it drains from the pits where waste is buried, it carries contaminants with it, such as heavy metals, which can end up in groundwater or waterways.

Starting household composting

The composting process only takes place from spring to early fall; however, you can sort and collect materials in your household compost bin in the fall and winter so that you are ready in the spring.

Compost bins must be kept out of the sun to avoid unpleasant odours and in a place that is accessible all year round. It is important to keep them on the ground so that microorganisms living there can access the organic matter. Compost bins should not be installed on cement or rock. Lastly, the ground must be flat for proper drainage.

Before placing the compost bin in its designate location, it is important to aerate the soil by turning it over to make it less compact and promote air, water and microorganisms circulation. Once the soil is turned over and well aerated, the compost heap can be started by forming a “nest”: small branches and twigs on the edges and dead leaves in the centre.

For better composting, it is recommended that the materials be deposited in successive layers, alternating between nitrogen-rich materials, or green matter, and carbon-rich materials, or brown matter. Here are some examples of materials that can be used in household compost:

  • Green matter: kitchen scraps, lawn or garden waste, eggshells (rich in calcium).
  • Brown matter: twigs, branches, dead leaves, hay, sawdust, coffee and tea grounds, dead plants and dried flowers.

At the beginning of the process, brown matter is to be preferred (such as the nest at the bottom of the compost bin). It should be two to three times the volume of green matter. Dead leaves are very useful at this stage. Afterwards, you can add as much brown matter as green matter, in thin successive layers (5 to 15 cm) to gradually reach a balance.

CAUTION – The following materials are to be avoided:

  • Meat, fish, dairy and fat waste attract small animals and may contaminate the compost.
  • Citrus peels are too acidic.
  • Garden waste containing seeds, weeds and diseased plants can spread diseases.
  • Printed packaging cardboard that contains heavy metals, waxed or plastic-coated cardboard, treated wood, BBQ briquettes and vacuum bags.
  • Residue from food or items that have been treated with chemicals.

Daily compost maintenance

To optimize the composting process, it is important to aerate the compost and keep it moist. Aeration oxygenates the matter and should be done every 10 to 15 days using a pitchfork or aerator. To moisten a compost heap that is too dry, it is recommended to add rainwater collected in a rain barrel, or water that has been used to cook vegetables and cooled. Conversely, to avoid having compost that is too wet, it should be protected from the weather by keeping the lid of the compost bin closed. Adding newspaper, soil or dead leaves helps to reduce the moisture content.

Odours provide valuable information on the condition of the compost and the corrective action to be taken. A smell of ammonia (pungent) means there is too much nitrogenous (green) matter. Carbonaceous (brown) matter should be added. An odour of rotten eggs (sulphurous) indicates that the compost lacks air and must be turned. A mouldy smell is a sign that the compost is too moist.

A few tips for managing compost input

  • Find a balance between brown and green matter. Observe and trust your senses.
  • Look at the texture and appearance of the compost: composting is effective if the materials are unrecognizable, turn into black soil, and give off only an earthy odour.
  • If possible, store dead leaves in a bag so that you can add some throughout the year. Carbonaceous matter may be lacking in winter or summer.
  • Do not add too many grass clippings at the same time. They can be left out to dry or left on the lawn, which allows for grass recycling.
  • Regular aeration improves the quality of the compost. Aerate every 10 to 15 days. Start by recentering the material that has built up on the edges and then mix it with the matter at the centre.
  • The more diversified the material is, the better it will be composted. Alternate layers of green matter with layers of brown matter; for example, place food waste in the bin with newspaper, cardboard, or sawdust.

Household compost bins can be purchased for $25 at the City Hall multiservice counter.

Books donated to the Pointe-Claire Public Library

  • Bruneau Laura (2020). Permaculture d’intérieur : composter chez soi, refaire pousser ses légumes, créer son potager d’intérieur, planter ses noyaux, Éditions Rustica
  • Ebeling Eric, Hursh Carl, Olenick Patti (2017). Composting Basics: All the Skills and Tools You Need to Get Started, Stackpole Books (Gilford, Conn.)
  • Michaud Lili (2016). Le compost : pourquoi ? Comment ?, Éditions MultiMondes (Montréal, QC)