Science·What on Earth?

Better lawns and gardens: Creating an environmentally friendly yard

In this week's issue of our environment newsletter, we look at how to grow a more sustainable lawn and give you the skinny on thorium, which many people see as a greener nuclear fuel.

Also: Thorium, the greener nuclear fuel

(Sködt McNalty/CBC)

Hello, people! This is our weekly newsletter on all things environmental, where we highlight trends and solutions that are moving us to a more sustainable world. (Sign up here to get it in your inbox every Thursday.)

This week:

The green grass of home: How to grow an 'alternative' lawn

(Taylor Logan/CBC)

For many people, their lawn is a source of tremendous pride and the object of great care. But "turf" lawns are not naturally occurring plants — and that has broader implications.

The concept of a lawn originated in medieval times, on the land outside European castles. The short grass enabled watchmen to see friends or foes approaching from afar. Lawns soon became something of a status symbol among the rich.

Today, lawns still hold visual appeal, but they also have significant environmental impacts. 

During the summer months, water usage in Canada peaks, and a half to three-quarters of all municipally treated water is used for lawns. To keep them looking their best, many of us have historically turned to pesticides and herbicides that contaminate soil, water, turf and other plants. Pesticides and herbicides can also be toxic to fish and insects important to the ecosystem of our gardens.

Lawns are considered carbon sinks — i.e., they absorb more carbon than they release as carbon dioxide. But a study by Appalachian State University says that if you take into consideration the amount of energy that goes into producing fertilizer and fresh water, as well as mowing, lawns overall produce more greenhouse gases than they can take in. 

Plus, lawns create homogeneity of vegetation when a diversity of plant life is necessary for a strong and healthy ecosystem. Without diversity, pollinators, insects, birds and other wildlife have nothing to eat and nowhere to live. So what's the solution?

"Replacing lawns with native habitats is the best option, but other practices also can reduce impacts," said Amanda Rodewald, a professor and senior director of conservation science at Cornell University. 

The best way to create a native habitat is by creating an alternative lawn. Substitutes include xeriscaping and permaculture, and are known to be better for the environment. 

  • Xeriscaping (pronounced "zerascaping") replaces grass with low-water, low-maintenance plants, such as succulents, cacti and warm climate grasses. Perfect for warm weather areas, xeriscaping can reduce water use by up to 60 per cent, and only requires occasional weeding and mulching, thereby cutting the output of greenhouse gases into the air.

  • Permaculture is a farm-like system that takes a diverse range of plants and cultivates them into a garden that sustains itself. Instead of having one type of plant that requires fertilizer and pesticides, a permaculture combines plants that complement each other's ecosystem, creating a more nitrogen-rich ground and smothering unnecessary weeds. Creating a permaculture garden can be done in any habitat with a little research, and depending on the size, will only need a couple of hours a month at most to maintain.

If you can't change your lawn to be the perfect habitat, Rodewald suggests reducing the size of your lawn by incorporating native flowers, shrubs and trees that are attractive and support biodiversity. Beyond that, she advises taking a more laissez-faire attitude.

"If your lawn is necessary, eliminating the use of chemicals, mowing less frequently and letting grass be taller can reduce energy consumption, water needs and attract a greater diversity of pollinators."

Taylor Logan


If you've got comments or suggestions, let us know.

Email us at

Old issues of What on Earth? are here.

How to create a vermicompost bin

(Taylor Logan/CBC)

In the last issue of the newsletter, I mentioned the vermicompost bin my roommate and I created in our apartment. Since then, I have gotten a lot of questions about what it is and how to make one. 

Here are some small tips on creating your own no-mess vermicompost bin.

Vermicomposting uses worms to convert food scraps into castings (a fancy name for worm poop), which is a very rich form of fertilizer. Red worms (also known as "red wigglers") are the best kind for composting. You can get them online or at a local bait store. Although some people may not find worms the most pleasant creatures to have living in your home, they're a great way to create a stink-free compost bin. And as long as you're feeding your wiggly friends, they'll stay safely out of sight in their bin.

First, you'll need a box with a lid (wood, metal or plastic is fine) as well as dirt, newspapers and food scraps. Drill small holes in the side of your box, near the lid and cover with netting. (We used an old pair of pantyhose and hot glue.) Then lay down a layer of damp newspaper, fill the box one-third of the way with dirt and put in your worms. Around 250 to 500 worms will do. 

The worms will start burrowing. Once they're underground, cover the dirt with saved up food scraps and cover once again with a layer of dirt. Make sure to avoid citrusy, spicy or hard food, as the worms can't digest these. If the worms come to the top, it means the compost is too wet. To fix that, leave the lid off in the sun for 20 minutes.

Now you have your own vermicompost bin. Stir once a week and enjoy your new little friends!

Taylor Logan

The Big Picture: Net-zero carbon targets

We've seen a number of countries recently offer timelines for when they aim to be "net-zero carbon," which means either balancing carbon emissions with carbon removal (through carbon capture and offsets) or going carbon-free. Here's a list of where the most ambitious nations stand.


Hot and bothered: Provocative ideas from around the web

What's the deal with thorium?

(Pallava Bagla/Corbis via Getty Images)

A few months ago, we looked at the pros and cons of nuclear power. More recently, CBC News took a closer look at small modular reactors and how new technology could fuel nuclear's comeback

That prompted some of you to write in asking about thorium as a potentially greener nuclear fuel alternative to uranium.

According to the World Nuclear Organization, thorium has a few advantages over uranium:

  • It's three or four times more abundant in the Earth's crust.

  • It generates lower levels of nuclear waste, especially the kind that takes more than 10,000 years to decay.

  • The use of thorium in most reactor types leads to "extra safety margins."

So, given decades of experimentation in Canada and around the world, why are there no commercial reactors out there running mainly on thorium?

A big challenge is that you can't generate nuclear power directly from thorium — first, it has to be converted into uranium (though not the same kind normally used in reactors). And what's the key catalyst for that conversion? Well, generally, it's regular uranium nuclear fuel.

That means "thorium fuel" is always a mixture of thorium and uranium, which makes things more expensive and complicated in a conventional nuclear reactor, and doesn't eliminate the challenges associated with uranium.

The benefits of using thorium "don't necessarily outweigh the costs," said Markus Piro, an assistant professor at Ontario Tech University, who holds a Canada Research Chair in Nuclear Fuels and Materials. "At this point, there's not a whole lot of interest in Canada."

That's because uranium works, Piro said. "And we have lots of it."

Piro noted that because uranium nuclear fuel is mixed in with the thorium fuel, long-term disposal will still need to be in the same kind of underground repository with the same requirements as with conventional uranium fuel.

There are two things that could make thorium more attractive in certain circumstances:

  • Countries such as India and China are interested because they have limited uranium and more abundant thorium resources.

  • New reactor designs, such as molten salt reactors, could be better suited to thorium. That's because such reactors use liquid fuel, where different components can be easily processed and separated, including the waste.

Piro sees "potential" in thorium fuel, but said the true power advantages lie in the design of the reactor. "The excitement, the benefits and all that really come with the reactor technology as a whole."

Emily Chung

Stay in touch!

Are there issues you'd like us to cover? Questions you want answered? Do you just want to share a kind word? We'd love to hear from you. Email us at

Sign up here to get What on Earth? in your inbox every Thursday.

Editor: Andre Mayer | Logo design: Sködt McNalty


To encourage thoughtful and respectful conversations, first and last names will appear with each submission to CBC/Radio-Canada's online communities (except in children and youth-oriented communities). Pseudonyms will no longer be permitted.

By submitting a comment, you accept that CBC has the right to reproduce and publish that comment in whole or in part, in any manner CBC chooses. Please note that CBC does not endorse the opinions expressed in comments. Comments on this story are moderated according to our Submission Guidelines. Comments are welcome while open. We reserve the right to close comments at any time.

Become a CBC Member

Join the conversation  Create account

Already have an account?