Americans are in love – or, as some might say, addicted – to their lawn. Beautifully landscaped, bright green grassy plots are ubiquitous in most suburbs, where the majority of Americans live. At least 40 million acres in the United States, an area larger than the state of Georgia, are covered with lawn, the typical lawn plant.
But what if growing and cultivating this grass contributes to the biggest environmental crises on the planet, including water pollution and climate change?
This is the view of some scientists who are increasingly talking about the disadvantages of the lawn and the need to turn to alternatives – or, at least, to more sustainable means of lawn management.
“There are four things that every piece of land must do to achieve ecological sustainability: carbon sequestration, pollinator support, food web support. And the other is the management of the catchment area. “A lawn is the worst choice in all of these four ecological goals,” Douglas Talami, a professor of agriculture and natural resources at the University of Delaware, told Yahoo News.
For climate change, the only major problem is not what a lawn does, but what it does not. Every plant stores carbon dioxide – the most common gas that traps heat that causes global warming. The more carbon stored, the better for the environment. But not all plants store the same amount of carbon. In general, the amount of carbon bound is related to the size of a plant and its root system. This is why logging old trees, which tend to be taller than younger trees, is particularly bad for climate change.
Compared to other plants that could grow in a yard, such as shrubs and trees, the grass has a very shallow root system. Much less of it grows above the ground, especially if you mow your lawn every week to keep it tidy and short. “When it comes to carbon sequestration, lawns fail,” said Tallamy, author of Nature’s Best Hope: A New Approach to Conservation That Starts in Your Yard.
Then there’s lawn maintenance and the machines many Americans use to mow and mow their lawn: gas lawn mowers and leaf blowers. According to the Environmental Protection Agency, gas-powered lawnmowers use 800 million gallons of gasoline – and spill an additional 17 million gallons of oil – each year. Two-stroke engines used by lawn mowers and leaf blowers are particularly dirty because they do not burn about 30% of the fuel they use, which releases volatile organic compounds.
A 2014 study found that a two-stroke idle scooter releases 124 times more volatile organic compounds than an idle car or truck. The EPA states that using a standard gas-powered lawn mower produces as many volatile organic compounds and nitrous oxide – a powerful greenhouse gas – as driving an average of 11 new cars in the same amount of time. Overall, according to the agency, lawn mowers account for 5% of US (non-climatic) air pollution. In addition, many lawns are mowed by a gardener who visits regularly, burning gasoline on the way back and forth.
“Lawns depend on fossil fuels, period,” Douglas Kent, a landscape contractor who teaches at Cal Poly Pomona, told Yahoo News. “It does not have to be, it’s just the way we maintain them – the mowers, the blowers, the edges.”
Then there are the emissions associated with fertilizer production. The most important component of fertilizer is usually ammonia, which contains nitrogen that helps plants grow. Ammonia is produced at high pressure and at high temperatures. It therefore requires a lot of energy, which is usually provided by fossil fuels such as coal and natural gas. Ammonia production is responsible for more than 1% of global greenhouse gas emissions.
“[Lawns] “They are huge consumers of nitrogen and nitrogen is the most energy-intensive nutrient we produce,” said Kent.
“When you add all this energy we throw to the lawns and compare it to the amount of biomass stored in the soil and the web, you end up with 1 acre of lawn. [that] “It contributes about 3,112 pounds of carbon dioxide a year, which equates to 156 gallons of gasoline.” (He made this calculation, based on previous research on data inputs, for his book, “A New Era of Gardening: A Book on Gardening for Oxygen and a Healthier Atmosphere.”)
Many of the same characteristics that make most well-groomed American lawns clearly contribute to climate change are also forcing them to fail the other Tallamy viability tests. Fertilizer, for example, is usually mixed with a herbicide to kill weeds – both in one product are referred to as “weeds and feed”.
But a human weed is the food of an insect. Weed-dependent weeds, such as clover and dandelions, are systematically removed from lawns daily. And pollination is the very basis of biodiversity.
“Most vertebrates do not eat plants directly: they eat things that plants eat, especially insects,” Tallamy observed.
Likewise, short, regularly mowed grass does not absorb much water – an increasingly important task as climate change leads to more floods from stronger storms – and this runoff can channel fertilizers and herbicides into lakes, rivers and oceans, poisoning them. fish and hurting swimmers.
“Lawns are destroying our watersheds because, first of all, they do not retain the water that other plants hold,” Tallamy said. “It’s almost like paving the ground during a hot, dry summer.”
Grass is the most widely used irrigated crop in the United States, and lawns use 3 trillion gallons of water annually. Due to higher temperatures and more severe droughts associated with climate change, water scarcity has become a crisis in much of the West, forcing local governments to limit the amount of water that residents can use outdoors, although many homeowners housing allegedly ignored the rules.
Certainly, lawns are not the only harmful features of the yard. A concrete patio, which comes with its own carbon emissions from concrete production, has no ecological benefits at all.
Therefore, tearing a lawn and paving it would not be useful. But what should you replace it with? Most experts suggest just cutting back on grass and swapping out some larger plants that will absorb more carbon and water. A tree that provides shade also reduces the amount of water that evaporates from the rest of the grass, which means it should require less water.
Ideally, some scientists say, only people who live in areas wet enough to grow grass without additional irrigation will have grass, and people in drier areas will plant less thirsty native species, such as the desert cactus.
There are also ways to care for a lawn with a lower impact. Using only manual tools, such as a lawn mower or electric, will remove emissions from two-stroke engines. According to the Electricity Research Institute, replacing half mowers in the United States with electric mowers would save as much emissions as removing 2 million cars from the road. Taking a more natural approach to lawn management – cutting it less often, skipping the herbicide and letting the clovers and dandelions grow – would also minimize the impact.
Some state and local governments are beginning to take action on the worst environmental disadvantages of lawns. In response to complaints about the noise of gas-powered lawn mowers and leaf blowers, as well as emissions, California Gavin Newsom signed a bill last October that would phase them out in the state.
“It simply came to our notice then [lawn] “By default, we put some plants in our yard and everything else becomes lawn,” Tallamy said. “I want to reverse it. “I want to have a lot of plants and what is left over becomes grass.”