Is the lawn good or bad for the environment? You can look at this problem from different points of view and today I would like to examine the specific question; do lawns reduce CO2 levels.
A study done by Scotts Miracle Gro concluded that “The lawn is a good and valued resource for sequestering carbon, even under various typical lawn management practices”. Is this really true??? The answer is more complicated than you might think.
Carbon Sinking CO2
In our modernized society we produce too much CO2 (Carbon Dioxide) and if it is not causing global warming, the excess levels certainly don’t help the problem. One way to get rid of excess CO2 is to grow more plants. Plants take in CO2 and using photosynthesis they convert it to carbon and oxygen. The oxygen is released into the air and the carbon is used to build plant parts like wood, leaves, stems etc. A mature forest holds vast quantities of carbon.
It is ‘common knowledge’ that forests are great at removing excess CO2 – right? This is a myth–for details see my post Do Forests Remove CO2? But for now let’s assume that forests do remove CO2. Following this line of logic, it seems to make sense that a lawn would also remove CO2 from the air. Grass after all is a plant and as plants grow they do remove CO2 from the air.
Is Grass a Carbon Sink?
Grass does remove CO2 from the air, but growing grass also produces CO2 – this is called a ‘carbon cost’. How much CO2 is being produced in growing and maintaining the grass?
Scientists have coined the terms ‘carbon sink’ and ‘carbon source’. A carbon sink is a system that stores more carbon than it produces. A carbon source is a system that produces more carbon than it stores (ex automobile). For the benefit of the environment we need more sinks and less sources.
What is the difference between CO2 and carbon? In environmental discussions the two terms seem to be interchangeable to some extent. It is CO2 in the atmosphere that is the problem for global warming. Plants convert CO2 to other forms of carbon such as wood. When plants die, the carbon in the plant will again be converted back to CO2. Oil is the result of dead plants – a form of carbon. When we use gasoline, which contains a lot of carbon, it gets converted to CO2. The conversion of carbon to CO2 and CO2 to carbon is a continual cycle.
Maintaining grass produces carbon (or CO2). Running the mower, watering the lawn, and even the fertilizer we apply all produce CO2. The mower burns gasoline and converts it directly to CO2. In order for you to have water, the municipality must pump it around, and filter it – this all requires energy and the production of energy produces CO2. Fertilizer needs to be mined, then processes and then delivered to your door. There are lots of engines burning fuel to make this happen.
The Scotts Miracle Gro article mentioned above and a report from Native Plant Wildlife Garden go through the calculations to determine how much CO2 is produced while maintaining grass and how much is absorbed by the grass. I won’t go into the details here. It is no surprise that the two sources of information disagree with the conclusion. The one group is promoting lawns and lawn care and the other is an environmental group opposed to lawns.
Does It Really Matter Who is Right?
I don’t think so. Let’s look at it in more practical terms.
There is absolutely no doubt that it is better for the environment to have natural grassland or a forest instead of a lawn. Any time we reduce the amount of gasoline we burn, or reduce the use of man-made products (water and fertilizer) we are doing good things for the environment. Is a lawn a good carbon sink compared to a forest or grassland – probably not.
People want lawns. No matter what the calculations say – we still want lawns.
The solution is fairly simple. Don’t make your lawn any bigger than you need. Have just enough to let the kids play a bit, and to make the house look good. If you don’t use the lawn, consider making it a natural wildlife place. If you have a larger lot, consider reducing the amount of lawn by converting some of it to a more natural environment. The lawn out front of your house is there for esthetics in most cases. This can easily be replaced with better options. Even maintained gardens are better for the environment than lawns.
Don’t Maintain Your Lawn.
You read right. Lawns don’t need much regular maintenance. Leave grass clippings on the lawn to fertilize it. Don’t buy extra fertilizer or at least reduce the amount you use – I don’t fertilize my lawn. Don’t water your lawn–most cold climate lawns naturally go brown in hot weather–accept this fact. It does need mowing from time to time, but it does not need it every few days. If you water less and fertilize less, you will mow less.
Allow moss and clover to grow in the lawn. You might even think of planting clover in the lawn.
Both sets of calculations in the above references assume a certain level of maintenance. If you reduce the maintenance, you will reduce your financial costs and you will reduce the amount of CO2 produced by your lawn.
Is a lawn a carbon sink? Is it good or bad for the environment? The answer depends on how you maintain it. If you follow my advice and reduce the maintenance, the lawn is probably a carbon sink and good for the environment. I don’t think it is as good as a natural forest, but we are human and want some lawn. Having grass is not our biggest environmental problem. Grass maintenance is a big problem.
More Articles About Lawns
How to Get Rid of Moss in Lawns
Biological Liquid Dethatcher for Lawns – Do They Work?
How Long Does Grass Seed Take to Grow?
I work with high yield farmers who have decreased the need for fertilizers by increasing organic matter in their soils. Organic matter equals CO2. NOte the following article
https://sccs.stanford.edu/sites/g/files/sbiybj17761/files/media/file/10_-_schmidt_c_sequestration_in_soils_0.pdf
OK – how is this related to lawns?
I think most people agree that increasing organic matter in soil increases C sequestration. And higher organic matter levels may result in fewer fertilizer requirements. One problem is finding those organic sources. When we move them from one farming system to another, you increase organic matter in one and decrease it in another, not to mention the CO2 produced to move it.
Is basic soil so different between crops? Watch the following power point by a Stanford professor.
file:///C:/Users/cvand/Downloads/10_-_schmidt_c_sequestration_in_soils_0.pdf
That is a file on your computer – nobody can access it!
I realize that some time has elapsed since this article was written, so hopefully we have learned some in the meantime, but the article misses some very important facts that have recently been uncovered. It is true that plants consume and then release carbon. What you are missing is the amount that may be sequestered in the soil by beneficial microbes. Studies of corn, which is a grass, by universities show that the potential for soil as a carbon sink is pretty vast. The problem is we add so many chemicals to soil, chemicals which suppress the microbiome, and dying microbes that are no treplicated release CO2. The average acre of corn consumes around 30,000 lbs of CO2. Depending on the health of the soil some percentage of that can be sequestered by healthy microbes. Lawns are no different. There are products, such as liquid compost extracts, and or compost teas that can improve the environment for microbe replication, which will help overcome excess chemical suppression of microbe replication. When added to the common sense practices you mention in the article, lawns can be a carbon sink.
Prove it. Show me the study that found higher carbon in soil under compost tea fed lawns.
Very interesting article, thanks. I do want to hear more about one of the replies to your article and that is by Sparafuciile on 4 May 2017. When I press reply, nothing happens. How do I reply to their message? Thanks.
So much of climate change is based on carbon rich material turning into CO2 and the ever increasing CO2 level from fossil fuel. History clearly shows that multi gigatons of oil, gas, and coal have been taken from underground and turned into CO2 and released into the atmosphere. Following the carbon, we now see that these multi gigatons of carbon reside in the atmosphere, have been absorbed in the oceans, and they have changed into the biological material that covered the land.
To reduce the CO2 buildup in the atmosphere major changes to reduce the use of the fossil fuel are being made but it is arguable that this change will do no more than reduce the speed of the increasing CO2 levels from fossil fuels. Our culture may need to consider the CO2 that is entering the atmosphere from plant material.
We all know that plants take CO2 out of the air as they grow. And, according to the scientific theory ‘The Carbon Cycle ‘ the ever increasing plant material WILL turn back into CO2. This can happen quickly (like we see in horrific forest fires) more slowly (as eaten by animals, insects, or microbes) or even more slowly with our intervention.
We have several major ways to slow CO2 production from plants 1. Dry it. 2. Freeze it. 3. Store it away from oxygen. 4. Keep it away from fire. 5.Change it into something that doesn’t degrade as quick. With thought and action gigatons of plant material can be collected and stored. Industries can adopt procedures that focus on slowing gigatons of dead plant material from turning back into CO2 and reduce this overlooked ever growing source of unchecked CO2 production.
If you keep the grass clippings from turning back into CO2, the carbon is still sequestered.
Awesome post keep it up!
I can tell that my lawn is sequestering carbon because the soil gets taller every year (it is soil, not just thatch). It’s probably grown two inches in the 20 years we’ve been there. However, I acknowledge that the carbon produced by the watering and fertilizing probably far outpaces it. I leave my clippings on the lawn and use a manual reel mower (Fiskars), but sadly I have to water as we live in a semi-arid desert (almost zero rain during the summer).
If you leave your grass to grow it might grow 2ft tall and then it slows down its requirement for CO2. However, If you regularly mow you produce a lot more grass it can be up to 6ft. So as long as you mulch the grass to refertilise the soil and you use an electric mower like (Ego) or even better a plug in mower and you switch to renewables or have solar on your roof your garden will definitely become a carbon sink in my opinion
There is a lot of new evidence that lawns remove flowering plants for pollinators to use and that lawns produce volatile organic compounds, especially when cut. For those reasons and more, people are replacing their lawns with misses and flowering found cover.
https://mobile.nytimes.com/2014/04/03/garden/gathering-moss.html