(Beyond Pesticides, February 5, 2010) While there are many great reasons for â€śgreenâ€ť spaces in urban areas, a new study has found that conventional landscaping practices are actually causing greenhouse gas emissions at a rate up to four times greater than the lawnâ€™s ability to sequester carbon dioxide from the atmosphere through photosynthesis. The study, which is set to be published in the journal Geophysical Research Letters, finds that nitrous oxide emissions from lawns are comparable to those found in agricultural farms, which are among the largest emitters of nitrous oxide globally.
â€śLawns look great â€“ theyâ€™re nice and green and healthy, and theyâ€™re photosynthesizing a lot of organic carbon. But the carbon-storing benefits of lawns are counteracted by fuel consumption,â€ť said Amy Townsend-Small, Ph.D., the lead author of the study and Earth System Science postdoctoral researcher at University of California, Irving (UCI).
Dr. Townsend-Small and her colleague Claudia Czimczik analyzed grass in four different parks near Irvine. Each park contained two types of turf: ornamental lawns such as picnic areas that are largely undisturbed, and athletic fields that are trampled and replanted and aerated frequently. Soil samples were evaluated over time to ascertain carbon storage, or sequestration, and they determined nitrous oxide emissions by sampling air above the turf. Carbon dioxide emissions were then calculated from fuel consumption, irrigation and fertilizer production using information about lawn upkeep from park officials and contractors.
In ornamental, conventionally maintained lawns, the study found that nitrous oxide emissions from fertilization offset just 10 percent to 30 percent of carbon sequestration. But fossil fuel consumption for management releases about four times more carbon dioxide than the plots can absorb. Athletic fields fare even worse, because they do not trap nearly as much carbon as ornamental grass but require the same emissions-producing care, due to soil disruption by tilling and resodding.
Turfgrass is increasingly widespread in urban areas, making it one of the most commonly irrigated crops, covering 1.9 percent of land in the U.S. Fortunately, there are ways to avoid chemical-intensive landscaping. Harvard University, for instance, has committed to managing its entire 80-acre campus with pesticide-free, natural, organic lawn and landscape management strategies, all the while saving tens of thousands of dollars a year.
Some Beyond Pesticidesâ€™ Board Members are doing tremendous work in controlling turfgrass without the use of toxic pesticides, excess fuel or fertilizers. Chip Osborne, president of Osborne Organics, for instance, is a professional horticulturist with over 30 years experience and an expert on building and transitioning turf to organic care. He converted his retail greenhouse operation to an organic management plan and teaches aOrganic Land Care Basic Training program.
Many cities nationwide are also replacing toxic pesticides with goats, thanks in part to the help of Lani Malmberg, president of Ewe4ic Ecological Services and a Board Member of Beyond Pesticides. You can learn all about the environmental benefits of goat grazing in the report, â€śSuccessfully Controlling Noxious Weeds with Goats.â€ť
Another way to reduce the impact of chemical-intensive agriculture on climate change is to grow an organic garden. Research suggests that organic techniques can reduce the output of carbon dioxide by 37-50%, reduce costs for the farmer, and increase our planetâ€™s ability to positively absorb and utilize greenhouse gases. The Rodale Instituteâ€™s Farming Systems Trial (FST – comparing organic and conventional) shows that organic techniques actually has the potential to lessen the impacts of climate change and restore soil fertility. This occurs through the drastic reduction in fossil fuel usage to produce the crops (approximately 75% less than conventional agriculture) and the significant increase in carbon sequestration in the soil (approximately 1000 lbs. of carbon per acre).
You can hear Rodale Instituteâ€™s organic farm and garden expert Jeff Moyer, speak at Beyond Pesticidesâ€™s 28th National Pesticide Forum, Greening the Community. With 30 years at Rodale, he has helped countless farmers make the transition from chemical-based farming to organic methods.
For further information on being a part of the growing organic lawn care movement, see Beyond Pesticides’ Lawns and Landscapes program page.