Energy and Our Ubiquitous Lawns
There are 40.5 million acres of lawn in the United States. In caring for these lawns 800 million gallons of gasoline are burned every year. Of this the amount spilled annually while filling gas mowers is 17 million gallons. That’s enough gasoline for 146,000 hybrid cars to travel from New York to Los Angeles and back. (The Exxon Valdez spilled only 10.8 million gallons).
We Americans also use more than 7 billion gallons of potable water daily for lawn irrigation. Depending on where, that is 30 to 60% of residential water use, at a time when fast-growing populations (including in California) lack reliable access to clean drinking water.
Gardeners contribute to global warming in many ways. We consume energy directly, by using power equipment like mowers, leaf mulchers and blowers. Whether powered by gasoline or electricity, these tools contribute to CO2 emissions. The energy required for pumping and distributing irrigation water is another source of CO2. The more arid the area, the higher the water’s embodied energy.
Fertilizers and pesticides used in gardens and lawns account for still more energy consumption and CO2 emissions. People are often surprised to learn that the biggest contributors to greenhouse gas emissions from lawn care are nitrogen fertilizers. The manufacture of synthetic fertilizers is extremely energy intensive. Manures and other organic nutrient sources are a better choice because manufacturing-related carbon emissions are eliminated. But using any fertilizer (synthetic or organic) releases nitrous oxide gas, which has 300 times the atmospheric warming potential of CO2. Americans use 3 million tons of lawn fertilizers annually, which could be cut in half by simply leaving grass clippings on the lawn.
There are also over 30,000 tons of synthetic pesticides used on lawns annually, ten times more per acre than used by the average farmer. The embodied energy of chemical pesticides is high. And they are toxic: of 32 pesticides routinely used on lawns, 13% include known or suspected endocrine disrupters, 22% include reproductive toxins, 41% include ingredients banned or restricted in other countries, 53% include possible carcinogens, and all pose a threat to the environment, including water supplies, aquatic organisms, and non-targeted insects. Lawns also represent a huge natural habitat loss, especially along both highly suburbanized coastal regions.
For all this, Americans spend $30 billion on lawn care every year, $2.2 billion of it on pesticides. Why not, instead, reduce the size of our lawns — or eliminate it entirely — unless it requires little or no maintenance. Use hand tools on what remains. Once the lawn is downsized, a push mower provides a good opportunity for a bit of exercise. Grow a permaculture garden. Create an imaginative, low maintenance landscape. Choose materials with low embodied energy. Brick, cement, and concrete, for example, have larger carbon footprints than gravel and wood. Used brick and other recycled materials are good landscaping choices as well. And growing local woody plants is a great way to sequester carbon safely away from the atmosphere.