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The Grass Isn’t Always Greener — At Least for Your Lawn


Turns out the grass isn’t always greener, at least when it comes to lawns and their contribution to global warming.

That’s because keeping those green spaces glossy with fertilizer and other maintenance techniques actually offsets lawns’ carbon-trapping benefits, according to a new study in Geophysical Research Letters.

“Turfgrass” lawns, which make up nearly 2 percent of land in the continental U.S., act as carbon sinks, storing the powerful greenhouse gas in soil.

But if you consider what it takes to upkeep a lawn–that is, production of fertilizer, mowing, leaf blowing, and other practices, their collective greenhouse gas emissions are four times greater than the amount of carbon that lawns can absorb.

For instance, fertilizer releases nitrous oxide–commonly known as “laughing gas”–a greenhouse gas that’s 300 times more potent than carbon dioxide.

“Lawns look great–they’re nice and green and healthy, and they’re photosynthesizing a lot of organic carbon. But the carbon-storing benefits of lawns are counteracted by fuel consumption,” study leader Amy Townsend-Small of the University of California, Irvine, said in a statement.

Nitrous Oxide Emissions No Laughing Matter

Townsend-Small and colleague Claudia Czimczik focused on four parks in Irvine, each of which had two types of turf: athletic, for soccer and baseball, and ornamental, which includes picnic areas.

Over a year, the team took soil samples in the parks to measure how much carbon was stored. Researchers also measured how much nitrous oxide was being released by sampling air above the surface, and then estimated carbon dioxide emissions based on lawn-upkeep activities.

Not only did the irrigation, fertilizer, and other activities dwarf the lawns’ ability to store carbon, the nitrous oxide emissions were similar to those of agricultural farms, which are among the largest emitters of the gas in the world.

Although the study was limited to city parks, “there’s still the potential to reduce the carbon footprint of all lawns by reducing fossil fuel consumption,” Townsend-Small told Green Guide in an email.

For instance, she recommends using a rake and a push mower instead of leaf-blowing or power mowers, and limiting irrigation and use of synthetic fertilizers and pesticides.

–Christine Dell’Amore

tn_Christine DellAmore_03.jpg

Photograph by Philip Gould, NGS

More from National Geographic’s Green Guide:

Easy Organic Lawn Care

Fertilizer Buying Guide

Green Guide Home & Garden Hub


  1. Fred
    July 19, 2010, 7:29 pm

    That’s an interesting article.
    I learned many things here. Thanks!
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  2. benjovi
    July 19, 2010, 12:07 am

    The water alarm isn’t a life-changing crisis yet. Around my place, we are much better watered than some places are. Some area have decades worth of experience trying to convince their suburban citizens that a desert rock garden can be inviting too.
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  5. John
    July 1, 2010, 2:43 am

    Its necessary to mention that fertilizer releases nitrous oxide–commonly known as “laughing gas”–a greenhouse gas that’s 300 times more potent than carbon dioxide.
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  6. inter4522
    June 18, 2010, 2:53 pm

    There are so many chemicals that are placed in peoples lawn is so bad. We have to stop this to save our environment. There is definitely alternatives to these chemicals.
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  8. Linda
    May 27, 2010, 6:34 am

    If this gas emission is the only issue why can’t we hit it by following the guides that assist in choosing the proper fertilizer that are available in the market?
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  9. Viru
    May 7, 2010, 9:48 am

    I don’t think we should worry about the earth giving off carbon emissions. We should be looking at the tools we use for the up keep of such things a lawns and as sugested above look to reduce the use of fossil fuel consumption which is the real problem. In my opinion this is just one more reason for us to be putting alot more thought nd effort into finding a new, clean and abundant source of power! I mean can you imagine if we devloped a new way to power engines in cars that gave of ZERO emissions? We have the technology AND the inteligence to do so!
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  10. The Window Man
    January 25, 2010, 8:53 am

    We really need more articles like this one. I own a landscaping business and this is wonderful information to pass on. My customers will now go green…by my choice alone.
    “I am here to serve.”
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