January 21, 2010
We should all know by now that lawns of green grass aren’t so “green” for the environment. Keeping turf from turning brown wastes water; people use too much pesticide and herbicide, toxic chemicals that can contaminate the fish we eat and water we drink. And keeping lawns at a reasonable height burns fossil fuels, releasing greenhouse gases and other pollutants into the atmosphere. Now a new study in Geophysical Research Letters shows that turf causes yet another problem, this time from the fertilizer spread to keep grass growing.
Two Earth scientists from the University of California, Irvine, sampled two types of turf—ornamental lawn and athletic fields—at four California parks and calculated how much carbon dioxide the grass sequestered and how much nitrous oxide was released through fertilization. (Nitrous oxide is greenhouse gas that is about 300 times more effective than carbon dioxide at trapping heat in our atmosphere.) They also calculated how much carbon dioxide was released through maintenance.
For ornamental lawns that aren’t maintained frequently, such as picnic areas, the turf emits a significant quantity of nitrous oxide, but this was largely offset by the amount of carbon dioxide taken up by the plants. But athletic fields are maintained more closely, and they don’t sequester any carbon. These fields are thus adding to the amount of greenhouse gas in the atmosphere (and I would suggest that anyone obsessed with perfect lawn maintenance could also fit into this category of climate change contributor).
However, that patch of green isn’t necessary; we’ve been growing grass in our yards for less than a century. And there are plenty of alternatives. Xeriscaping (also called xerogardening), for example, uses native plants and mulch to limit the amount of water and maintenance needed in a garden. You could replace the grass with clover, which requires little water and no herbicides and could give you a constant supply of luck. Habitat gardening has the added benefit of attracting wildlife to your space. Or you can plant wildflowers—even replace your concrete driveway. My favorite solution is to replace your lawn with a meadow. Good luck, though, convincing your homeowner’s association on any of these.
(Hat tip: Blue Marble)
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