Climate Benefits from Urban Composting

Posted on Tuesday, 9 March 2021 under Stories

Composting is the backbone of urban agriculture. By integrating leaves, garden waste, and food scraps into home gardens, city growers are taking steps to combat climate change.

Private green spaces that reduce waste through composting can play a large role in regional sustainability. The numerous styles of composting accessible to city folk, such as piles, bins, and rotating containers, improve plants’ ability to harvest and store carbon in the soil. City dwellers who compost control the quality of their soil far more than those who purchase soil or subscribe to curbside collection programs. Additionally, home composting projects divert countless tons of waste and thus reduce the amount of methane from landfills.

Compost and Education Centre’s Site Manager and Community Education Coordinator, Kayla Siefried, says home compost projects reduce energy use, waste, and cost associated with conventional, store-bought soil. “When we’re creating our own compost out of our own waste, we’re closing the loop. So it’s a far more sustainable cycle where we take our waste and make it into something incredibly valuable to grow more food,” says Siefried.

Man using his hands to dig into compost bin

There are numerous ecological benefits to composting. Siefried says that compost not only increases your garden’s ability to sequester carbon, it also improves the quality of the food you grow because it adds organic matter, raises soil PH, and can bind toxins. “Then it makes your soil more disease and pest-resistant. That can really help with say, clubroots, slugs, or wood bugs that are eating your plants. If you’ve got a really healthy soil base, then your plants are going to be able to withstand the impact of those pests and diseases a lot better than if you had unhealthy soil,” states Siefried.

City Farmer Society’s Executive Director, Michael Levenston adds that home composting projects generate less environmental impacts than regional collection programs while protecting against unwanted materials often found in these large facilities. “Everyone puts whatever into their green bins, whether it’s pesticides, plastic, or some kind of compostable bag that’s never going to break down as compostable. Then it [compostable waste] travels by truck to a transfer station from where it is then moved to a larger facility, says Levenston.

One of the big advantages of making your own compost pile is generally you don’t have to worry if there’s something dangerous in it” - Michael Levenston. Share on X

Despite these environmental benefits, many urban dwellers may think their small spaces do not lend themselves to composting. Siefried says small yard spaces or boulevards are perfect places for simple passive cold-composting bin systems. “Using this type mostly involves ensuring there is a balance of green and brown materials. Greens are nitrogen-rich and browns are carbon-rich materials. Usually, the nitrogen-rich materials are coming from household vegetable scraps, and the brown materials are going to be things that you have to source. So in the fall, raking up a bunch of dry brown leaves and storing them in a bin or a bag means that every time you put your greens into your compost, right away, you’re putting a handful or three of browns on top of it,” advises Siefried.

She says your bin should alternate between layers of green and brown to ensure the biology and chemistry work to decompose the material. These layers are as important in your passive compost as air and moisture. “You can get air in the pile by poking it every once in a while with a garden fork, stick, or compost aerator. In the summer, make sure it’s moist enough because the worms and critters in there need water just like you and me,” adds Siefried.

Man wearing gardening gloves holding dirt with worms in it

By keeping this ecosystem productive, you also minimize smells which make your compost less attractive to rodents. Levenston recommends adding hardware cloth (metal mesh) to the base of your bin to further deter pests. “Leave it [the bin] clear around, don’t put it up against a fence or have a lot of weeds around. This will help you see if there are any intrusions, penetrations, or holes in it,” says Levenston.

Levenston stresses the importance of addressing these critters before more damage is done to surrounding structures. To further deter rodents, Siefried suggests home composters purchase cylindrical locking bins that have a baseplate. “Making sure we have that proper balance of carbon and nitrogen is very important. If you don’t have access to a whole bunch of leaves then you can rip up some newspaper, egg cartons, or you can buy a bale of straw. Always having the brown layer on top is really important for keeping smells at bay,” says Siefried.

It is essential to remember to not include things like meat, bones, dairy, cooked food, and fats in your outdoor cold compost bin. Siefried says digesters are a way to responsibly discard this home waste. She recommends a ‘green cone digester.’ “It’s a particular shape and it heats up. You put only nitrogen-rich stuff in like meat, bones, dairy, cooked foods, and fruit and vegetable scraps – you can even put pet waste in there. The system basically digests the food waste into a nutrient-rich liquid that then nourishes your soil. So if people have the funds or the ability to make one themselves, a digester can be a very easy solution to diverting food waste,” says Siefried.

Cold bins are a slower but effective composting process that utilizes both yard and food waste. For city folks who do not have space, Levenston recommends worm bins. “The worm bins can be very small, typically a Rubbermaid bin that you can have on your balcony. They don’t take care of as much waste; just food scraps,” says Levenston.

For more information about climate-friendly gardening, check out our Climate and Food Story series.