Urbanization study helps track impact of lawn care on environment

 Christopher Boyd

There are few luxuries that homeowners take pride in as much as their lawns. These gardening projects have been part of the quintessential American home picture since suburban communities first sprang up. These days, well-manicured lawns have become more ubiquitous thanks to urbanization across different landscapes and climates.

The popularity of lawns has raised concerns among environmental scientists. They require lots of water, which puts high pressure on the supplies of drought-stricken regions, and contributes to runoff pollution. Between pesticides and nutrient-rich fertilizers, lawn care may significantly contaminate watersheds.

To find out more, a multi-institutional team of scientists studied the lawn care practices of residents from six cities across the U.S., as published in the Proceedings of the National Academy of Sciences.

Algae blooms are a dangerOne reason why lawn care was of interest to the study's authors was the potential for fertilizers to enter local watersheds through polluted runoff. Many of these fertilizers contain large amounts of phosphorus and nitrogen, both of which contribute to algae blooms. This is problematic because abnormal algae growth in lakes, rivers and oceans gradually depletes the oxygen supply of the water. This kills off fish and other forms of life, creating what are known as "dead zones." This oxygen-poor water poses a major threat to the local ecosystem. Furthermore, algae can contaminate drinking water supplies with harmful toxins.

Eleven institutions led by Clark University surveyed about 9,500 households in Los Angeles, Phoenix, Minneapolis-St. Paul, Miami, Baltimore and Boston to learn more about lawn care practices in the U.S., including fertilizer use. The researchers asked questions pertaining to fertilizers and irrigation, and accounted for differences in climate and socioeconomic factors.

Results showed that 79 percent of respondents watered their lawns, and 64 percent used fertilizer.

"These numbers are important when we bear in mind that lawns cover more land in the United States than any other irrigated crop," study co-author Peter Groffman, a scientist at the Cary Institute of Ecosystem Studies, said in a statement. "What we do in our suburban and urban yards has a big impact, for better or worse, on the environment."

Other results showed that fertilizer use was similar in Boston and Miami, which both have different climates. Data from Los Angeles and Phoenix, which were the driest cities, revealed there was a positive correlation between irrigation and affluence.

Individual actions make a differenceUltimately, the study authors asserted that studies like this are important because they provide information on the sustainability of urbanization.

"The management of urban and suburban areas has a direct impact on water resources, carbon storage, and the fate of pollutants, like nitrogen and phosphorus," Groffman said in a statement. "Yards are also where our environmental knowledge, values, and behavior are likely generated. The good news is that individual actions, on a yard-to-yard-basis, can make a difference."

According to the U.S. Environmental Protection Agency, there are several ways to fertilize lawns without flooding the runoff with harmful chemical compounds. For example, consumers can buy slow-release products, as well as fertilizers that mainly use natural organic compounds. To help prevent runoff, these products should be applied away from sidewalks and driveways, where they can wash off. The federal agency also suggests that clippings be left on the lawn after mowing. This allows the old plant material to act as a natural fertilizer.

In an effort to conserve water, people who are about to start growing their lawns should mix compost into the soil to help it retain water. It may be ideal to plant seeds for grass that is drought-tolerant.