In November of last year the 2015 Climate Change Conference resulted in an agreement by the 195 member countries to reduce their carbon output “as soon as possible” and to do their best to keep global warming “to well below 2 degrees C”. Read more here.
All the talk of the Climate Change Conference in the media has motivated me to tackle the issue in this blog. What role do gardeners play in climate change?
It’s all about the Carbon
Well OK, its not technically just about carbon, but this is a gardening blog not a science blog, so in the interest of keeping it simple, I’ll focus on how gardeners can help reduce the amount of Carbon Dioxide (one of the three most lethal greenhouse gases) emitted into the atmosphere and how gardeners can help reduce the amount of Carbon Dioxide in the atmosphere by absorbing carbon.
Carbon Sinks and Carbon Sources
A garden can be either a carbon source or a carbon sink. A carbon source is one that emits more carbon dioxide than it absorbs. Conversely, a carbon sink absorbs more carbon dioxide than it emits. The ultimate goal would be to have a garden dramatically reduce or even eliminate its carbon emission, and ultimately to absorb carbon dioxide from the atmosphere.
Reducing Carbon Emissions in your Garden
Here are some simple practices that the home gardener can adopt in order to reduce their carbon footprint.
Reduce the Use of Power Tools – power tools that run on gas or electricity use carbon. Think about reducing the size of your lawn so that you can use a reel mower. Consider having informal hedges that can be maintained without the use of gas-powered hedge trimmers.
Reduce or get rid of your lawn – lawns require water and fertilizer to look like that beautiful lush lawn we see in our neighbourhood. Consider using decking or patios for outdoor living spaces. Think about using alternative ground covers if you want to retain some green space around your property that doesn’t require mowing, watering or fertilizer. If you want to keep your lawn, leave the grass clipping on the lawn. They will be a natural source of nitrogen which grass needs to stay green and healthy.
Use compost instead of synthetic fertilizers – home made compost, using food and garden scraps, can be used to feed plants effectively.
Reduce or eliminate water use in your garden – choose drought tolerant plants that require little or no water when established (read this article on drought tolerant plants for Vancouver). Add a mulch layer to your soil to increase the soil’s capacity to retain moisture and reduce evaporation (read this article on mulching). Install a rain barrel to capture rainwater during the rainy season that can then be used to water plants during the summer months. Choose the most efficient irrigation methods (e.g. drip irrigation versus pop-up sprinkler) in areas that will require water.
Turning Your Garden into a Carbon Sink
A garden that acts as a carbon sink basically absorbs carbon dioxide that is in the atmosphere. The term given to carbon absorption by soil and plants is ‘carbon sequestration’.
Carbon Sequestration in Soil – the carbon in soil is held in humus (the organic matter in soil). Humus is quite resistant to releasing its stored carbon into the atmosphere. By building up the humus content of your soil, your garden beds can be used to store carbon that might otherwise find its way into the atmosphere – in other words, your garden becomes a carbon sink. In order to build up the humus in your soil, you need to add compost. That’s a whole blog of its own, which I’ll write about soon. Another way of ensuring that carbon is not lost from soil is to leave the soil alone: rototilling and heavy digging accelerate the loss of stored carbon into the atmosphere.
Here’s a few practical tips on what the home gardener can do to store carbon in soil:
- use organic soil amenders instead of synthetic fertilizers.
- spread a yearly mulch on top of your garden beds, using an organic mulch.
- allow leaves and other plant residues to decompose on the spot (read this article on Chop and Drop’ gardening).
- grow nitrogen-fixing plants.
Carbon Sequestration in Plants – put simply, plants take carbon from the atmosphere and use it to produce their own food. This is part of a process know as photosynthesis. Some ways for home gardeners to increase this type of carbon sequestration in their garden include: planting trees and shrubs (woody plants sequester more carbon than perennials); growing tough, adaptable, native plants; avoiding disease-resistant plants; planting a diverse mix of trees, shrubs, and perennials (biodiverse gardens are more resilient).
So there are lots of ways that home gardeners can reduce their garden’s carbon footprint.
Want to learn more?
- Cornell University Resource Page on Climate Change and Gardening – lots of very interesting articles and links.
- “The Climate Conscious Gardener” – published by Brooklyn Botanical GardenContains many interesting articles on the topic. Available at VPL.
- Royal Horticultural Society – research on climate change.