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 reference #2 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.
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.
1) Photo Source: Jeremy Page
2) Is lawn a Carbon Sink? http://nativeplantwildlifegarden.com/is-lawn-a-carbon-sink/