Composting Worms and Climate Change

Contributed by Glenn Munroe

You CAN make a difference! If you are concerned about global warming, promote global worming!

Perhaps many of you have heard of the alternative form of back-yard composting known as vermicomposting, or composting with worms. Some of you may already own and operate a little “worm farm”. If you do, you know what a good job these little guys can do in turning your kitchen waste into top-quality plant food.

worm.pngBut this blog is not about how to compost with worms. If enough people are interested, we can certainly provide lots of that type of information in the future. Today I would like to focus on the relationship between composting worms and climate change. I think you will be surprised at the number of climate-related benefits we get from worms. I hope that it will get you thinking about becoming a vermicomposter, or, if you are one already, selling others on the idea.

Here are some of the ways in which compost worms help us to minimize greenhouse gases (GHGs), adapt to unavoidable (and already occurring) climate change, and generally sustain a healthy environment.

First of all, vermicomposting, like regular composting, keeps organic wastes out of landfills. This is very important in protecting against climate change. In fact, removing the organic component of the waste stream from landfills could eventually eliminate the landfill gasses that the Canadian government has estimated are responsible for about 4 per cent of the province’s GHG emissions. To put this in perspective, Ontario has a goal of reducing our emissions by 15 percent (below 1990 levels) by 2020.  As you can see from these numbers, just keeping organic residuals out of landfills could get us a quarter of the way towards our next target.

Secondly, vermicompost can essentially replace fertilizer in your garden and on your lawn. Many people have done this, myself included, with great results! In fact, the latest scientific literature confirms it; vermicompost can match or out-perform synthetic fertilizers. In addition, it is much more effective in this regard than regular compost.

Why is this important with respect to climate?

Fertilizer manufacturing is energy intensive. It accounts, by itself, for another 1 to 2 percentage points of GHG emissions. But that’s not all: the processes by which the raw materials for fertilizer are extracted, the transportation of these materials to the manufacturers, the shipping of the finished products to market and to your home, all result in even more GHGs. Finally, (as if that weren’t enough!), nitrogen fertilizers applied to soil usually release nitrous oxide (N2O), which is an even more potent GHG than methane (310 times the effect of CO2). It is not known exactly how much fertilizer contributes overall to GHG production, but the number is probably at least as high as the one for landfill gases.

Last, but definitely not least, vermicompost fights climate change through its beneficial impact on soils. It increases the level of carbon in soils, a process known as soil-carbon sequestration. This has several direct benefits: first, carbon stored in soils is removed from the atmosphere, which is the equivalent of reducing GHGs; second, that stored carbon increases both the nutrient content and the level of beneficial microbial life in the soil, which make the soil healthier and more resilient to things like changing temperatures and moisture levels; and third, the healthier soils have increased fertility, resulting in more plant growth and eventually more stored carbon (below ground, in roots and soil fungus).

JenniferRafieyanveggiesEvidence for the benefits of vermicomposting are accumulating rapidly in the scientific literature. Progress is slower in the conservative realm of practical agriculture; however, in some countries, such as Cuba and India, the agricultural use of vermicompost is established and growing. You can make a difference here in Canada by trying it out yourself and by telling others about it – particularly your gardening friends (although it works great on lawns and indoor plants, too). You CAN make a difference! If you are concerned about global warming, promote global worming!

Image Source:, creative commons

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