Your Lawn: How Green is that Grass?

Written by Lisa Orr, Mountainside Enrichment & Education

Does the smell of a newly mown lawn conjure up fond memories of spring fever, backyard games and barbeques? Let’s take a closer look at the facts behind lawn maintenance — a regular chore that takes 54 million Americans about three billion hours each year to complete!

In the Chesapeake Bay watershed, turf grass now covers more than 3.8 million acres, a staggering 9.5% of the watershed’s total land area. That’s more than the watershed’s pasture cover (7.7%) or row crops acreage (9.2%). In Frederick County, nearly 23% of our total land area is covered in grass.

What’s wrong with that? Nitrogen fertilization, pesticide application, water use, runoff from compacted soils, energy use, volatile organic compound emissions, biomass production (grass clippings), maintenance costs and labor – phew! – they’re all factors that affect not only our local waterways and the Chesapeake Bay, but also our national energy supply, the air we breathe, the water we drink, and our households’ budget and free time.

Based on the percentage of Frederick County turf grass in the Chesapeake Bay Watershed, we can estimate that County residents and businesses spend nearly $12 million each year to maintain lawns. They apply over 45,000 pounds of pesticides and nearly 516,000 pounds of fertilizer each year, and then use nearly 137,000 gallons of gas to cut grass, generating more than 18 tons of clippings. The annual volume of run-off from Frederick County lawns (roughly 3 cubic feet per second/day/yr) is equivalent to approximately 1,100 Olympic size swimming pools! This run-off includes a lot of pesticides and fertilizers that end up in our local waterways and the Chesapeake Bay. (Sources: CSN Technical Bulletin No. 8; Global Water Conversion Factors)

Then there is the impact of lawn equipment. According to EPA 2010 NONROAD Modeling, American households and lawn maintenance companies use nearly two billion (yes, billion!) gallons of gas each year in mowers, trimmers and edgers; they spill nearly 11 million gallons annually refueling. The impact of lawn equipment is greater than we might think. Before 1997, emissions from lawn equipment were unregulated. That means that far more air pollutants come from burning a gallon of gas in a mower than, say, a car whose emissions are regulated.

Fortunately, the EPA began setting emissions standards for lawn equipment in 1997 and emissions have dropped dramatically as a result. Phase 1 emissions standards reduced hydrocarbon and nitrogen oxide (NOX) emissions by 32%, and Phase 2 standards, implemented between 2001 and 2007, resulted in an another 80% reduction from Phase 1 levels. Even so, in 2008, EPA estimated that a new gas powered lawnmower produced as much volatile organic compounds and nitrogen oxides in one hour of operation as 11 new cars being driven for one hour. Starting in 2012, new lawn equipment was required to meet EPA Phase 3 standards . So the good news is that brand new mowers will be 90% cleaner than their pre-1997 counterparts.

Still, based on 2010 EPA modeling, one of today’s residential non-riding gas mowers produces 88 lbs/yr of CO2 emissions and 34 lbs/year of other pollutants. An individual riding mower produces 664 lbs/yr of CO2, and 206 lbs/yr of pollutants. The numbers for commercial equipment are up to 10 times higher. The high levels of carbon monoxide, VOCs, and NOXs emitted from garden equipment account for a significant portion of the nation’s air pollution and a higher percentage in metropolitan areas. Because this equipment is mainly used during the summer months when ground level ozone (the main component of smog) is at its highest, this causes more problems for those who suffer from asthma and other respiratory conditions.

What can be done? Reducing the amount of turf grass on your property is one strategy. Where possible, consider using a push-mower or electric mower. While electric mowers have emissions associated with the electricity that powers them, emissions from power plants are regulated better than those from lawn mowers. If you need a more powerful gas mower, buy the newest model you can and look for a label on the engine that says it meets EPA Model Year 2012 Standards; then be sure to keep it tuned up. Set the cutting level on the highest setting, avoid mowing during the hottest hours of the day, and mow less frequently.