As the finish carpenters pack up their tools and the last coat of paint dries, the new lawn is emerging outside. On what had been a barren construction site only weeks before, grass seedlings are poking up through a layer of carefully spread topsoil, fortified with fertilizer and protected with straw. Around the house are round balls of the most popular cultivars of yew, rhododendron, and cedar. A few tree saplings, staked in place on the gently rolling landscape, will in a few years begin providing shade where the owner can sip lemonade during a break from her weekend lawn-mowing chore.
Though the shrubs and trees will vary by region, this basic scenario is repeated over a million times each year as new single-family detached houses are completed and the lawn put in. The process is not much different with most commercial buildings, though the scale is larger and the landscaping budget may permit larger trees and established sod instead of grass seed to be planted. Is there anything wrong with this process? Yes, from an environmental perspective, plenty.
What’s Wrong with Lawns?
Americans spend over $25 billion each year on an estimated 50,000 square miles of lawn—an area larger than the state of New York—according to the Lawn Institute. The environmental impacts of lawns and lawn care fall into several broad categories: fertilizers, pesticides, water use, and air pollution from lawnmowers.
Fertilizers. We use 3 to 6 million tons of fertilizer each year to keep our lawns healthy (calculated from estimates provided by The Fertilizer Institute in Washington, DC). Runoff of lawn fertilizer into streams, lakes, and ponds contributes to eutrification (excessive algae growth that results in oxygen depletion), which can dramatically alter or destroy aquatic ecosystems. Even if the fertilizers do not run off our lawns (lawns do hold chemicals pretty well), the production of most nitrogen fertilizers consumes huge quantities of fossil fuel.
Pesticides. We apply 34,000 tons of herbicides, insecticides, fungicides, and various other pesticides to our lawns each year, according to the U.S. Environmental Protection Agency (Pesticides Industry Sales and Usage: 1990 and 1991 Market Estimates, Fall, 1991). This amounts to over 2 pounds per acre. These products cost homeowners $1.1 billion, and account for 14% of total pesticide sales in the U.S. (34% of insecticide sales). We use these chemicals to keep out unwanted animal and plant species and maintain what are essentially single-species monocultures of turf grass. Lawn pesticides can pose a significant health risk for humans (especially children), and their runoff into streams and other bodies of water can be damaging to natural ecosystems. Because tree roots extend far beyond the spread of their branches, herbicides applied to lawns can kill trees as far as 60 feet from where they are applied.
Water. We consume vast quantities of water to satisfy the moisture requirements of lawns. The authors of
Xeriscape Landscaping (see below) point out that in the U.S. we pump an average of 82 billion gallons of groundwater every day, while the daily recharge rate (through rainfall and runoff) is only 61 billion gallons. Most of our turf grasses are native to Europe and adapted to relatively high rainfall environments. The most recognized species, Kentucky bluegrass (belying the name, it too is an immigrant from Europe), requires 35 to 40 inches of water per year, yet it is widely grown in areas with as little as 14 inches of natural precipitation; the rest of that moisture must be provided by irrigation or sprinklers. In some parts of the country, lawn irrigation is the single largest use of water; in urban areas of Texas, for example, 40-60% of the water supply is used for landscape watering. During the summer months, landscape watering can easily account for 50-80% of water use, according to the Texas Water Development Board.
Air Pollution. Fueling the U.S. fleet of 40 million lawnmowers consumes several hundred million gallons of gasoline each year (quite a few Exxon Valdez-sized tankers’ worth). More significantly from an environmental standpoint, lawnmowers are far more polluting than automobiles. Though they use only a tiny fraction of the gasoline that autos use, they emit as much as seven percent of the total VOC air pollutants in some urban areas, according to Paula VanLare of the Mobile Sources Office of EPA. Our worst lawnmowers environmentally, those with two-stroke engines, emit as much air pollution each hour (excluding CO2) as a new car with California pollution control standards driven 2,200 miles, according to Bill Welch of the Center for Emission Research, Analysis and Certification.
Not surprisingly, California leads the nation in addressing pollution emissions from lawnmowers. New pollution standards, to take effect with the 1994 model year, will significantly cut emissions from new lawnmowers. Charles Emmett of the California Air Resources Board noted that switching from a lawnmower with a two-stroke engine to one with a four-stroke engine reduces pollutant emissions by about ten-fold, and that the new standards will result in a three- to four-fold improvement in four-stroke engines. Under the new regulations, virtually no two-stroke engine lawnmowers will be sold in the state.
The Edison Electric Institute, the Electric Power Research Institute, EPA, and various utility companies throughout the country have begun a program to measure environmental benefits of replacing gasoline-powered lawnmowers with rechargeable electric mowers. EEI claims that the electric lawnmowers will decrease hydrocarbon and nitrogen oxide emissions more than 70-fold, even taking into account the emissions associated with electricity generation. The benefit might be even greater than that, since currently available estimates of pollution emissions tend to be for
new equipment; old lawnmowers may be a lot worse. Gasoline mowers collected through the program are currently being tested for emissions.
Ecology. In addition to these direct environmental impacts of lawns, there is also an impact on natural ecosystems. Like cornfields, chemically managed lawns are barren ecosystems comprised of just a few principal plant species and whatever microorganisms and larger animals are able to survive the chemical management strategies. In the Midwest, the water and lime applied to new lawns ultimately killed the ancient white oaks that new houses were nestled beneath. DDT and some of the most environmentally damaging chemicals that Rachel Carson alerted us to in the early 1960s are now gone (and many bird species are gradually recovering), but we are applying greater quantities of pesticides to lawns today than we were thirty years ago.
One cannot, in fairness, focus only on the problems with lawns; they have many advantages too, not the least of which is the monetary value they add to houses. On the environmental side, lawns convert carbon dioxide into oxygen and thus help to alleviate our global warming concerns. Lawns absorb and help break down various atmospheric pollutants, including sulfur dioxide, ozone, hydrogen fluoride, and peroxyacetyl nitrate. The Lawn Institute claims that an acre of flourishing lawn “will probably absorb hundreds of pounds of sulfur dioxide during a year” and that a half-mile-wide turf area on either side of a highway will mitigate most of the pollution from those vehicles (though they will not come close to offsetting CO2 emissions).
By effectively holding water, lawns control erosion and minimize the runoff of chemicals; most agricultural crops, by comparison, are far more prone to environmentally damaging run-off and erosion. The Lawn Institute says that a healthy lawn absorbs rainfall six times as effectively as a wheat field and four times as effectively as a hay field. Lawns also help keep buildings cool and thus reduce cooling costs. They provide pleasant areas for kids to play and adults to socialize—bringing us out-of-doors into the (hopefully) fresh air. They cut down on noise and glare. They build up topsoil. They protect houses from fire.
Finally, you might have trouble selling your next house if it did not have some lawn around it. Lawns are what most home buyers and office building owners have come to expect, and dissuading them of this desire will be neither easy nor fast.
Alternatives to Lawns
It is time to curb our appetite for vast stretches of lush green lawn. While lawns are generally better than no vegetation at all, there are major environmental problems with conventional lawns and conventional lawn care. Environmentally concerned builders and developers can play an important role in bringing about a transition away from lawns. This will be a gradual transition, since lawns are part of the American image and our way of life. In fact, many municipalities have ordinances or zoning bylaws that
require homeowners and businesses to maintain lawns and keep them cut to a certain height. Even when such laws do not exist, societal pressure may prevent a wholesale shift away from lawns.
The primary alternative to lawns is the native vegetation that would have been appropriate to the area. This might be woodland, open fields, prairie, marsh, or desert. Minimal upkeep can maintain fields or prairie, keeping woody vegetation from encroaching. Native landscaping is becoming more and more popular throughout the U.S. and Canada. Numerous books, newsletters, societies, and clubs are devoted to wildflower and native landscaping (see below). Chances are good that there’s an organization, or at least good resources, with specific information appropriate to your part of the country.
When lawns cannot be avoided, we should strive to produce lawns that will be less damaging to the environment, and we should limit the area devoted to lawn to a size that can easily be cut with a rechargeable electric lawnmower or manual reel (push) mower (yes, these are still manufactured, by the Great States Corporation). Many of the decisions relating to lawns and lawn care will be up to homeowners or commercial building owners—not builders or designers. But we can play an important role in presenting options to our clients.
Strategies for replacing lawns with environmentally superior landscapes, as well as strategies for producing better lawns, are presented in the accompanying checklist.
While you as a builder or designer may not need to become an expert on environmental landscaping strategies, you may well want to point clients in the right direction for information on this issue. The following books (and a video) provide a great starting point—for you or your clients.
The Environmental Gardener. Edited by Janet Marinelli, Brooklyn Botanic Garden, Brooklyn, NY, 1992. 95 pages; $6.95.
Landscaping with Wildflowers: An Environmental Approach to Gardening. Jim Wilson, Houghton Mifflin Company, Boston, 1992. 244 pages; $18.95.
Naturescaping: A Landscape Alternative. A videotape produced by Sam Love, Public Production Group, Washington, DC, 1992. 29 minutes; $29.95 plus $3.95 shipping. (Not highly polished, and with an idiosyncratic sense of humor.)
Requiem for a Lawnmower, and Other Essays on Easy Gardening with Native Plants. Sally Wasowski, Taylor Publishing Company, Dallas, TX, 1992. 180 pages; $15.95.
Xeriscape Gardening: Water Conservation for the American Landscape. Connie Ellefson, Tom Stephens, and Doug Welsh, Macmillan Publishing Company, New York, 1992. 324 pages; $30.00.