From KEPHARTK@mg.sdstate.edu Sat Apr 25 22:17:24 1998 Date: Wed, 22 Apr 1998 8:17 -0600 From: "Kephart, Kevin PltSc." To: forage-mg@web.CSS.ORST.EDU Subject: Grass Gas Colleagues: I found this information on the Discovery Channel web site last night. Kevin ************************************************************************** ************** Study: Grass is Environmentally Unfriendly Lawns and grasslands release vast quantities of pollutants into the air, according to one of the first studies of gaseous emissions from grass and clover. Firing up the mower and cutting the grass will just make things worse. Scientists from Australia's CSIRO Research Institute and Monash University have found that emissions of chemicals increase approximately 100-fold after grass is cut, and take hours to reduce to their original levels. Cattle grazing or trampling will have a similar effect to mowing, increasing emission rates from grass. Scientists believe that some of the additional gases released by cut grass are natural antibiotics, which act to disinfect the wound site. Gases released by grass include the volatile organic compounds methanol, ethanol, propanone and butanone, according to CSIRO. This study has shown that grasslands around the world may be one of the biggest sources of the gases methanol, and perhaps ethanol, in the atmosphere. "It's not just cars and industry, or lawnmowers themselves, that cause air pollution," says Ian Galbally, from the CSIRO Division of Atmospheric Research. "Plants release highly reactive hydrocarbons that can add significantly to photochemical smog problems," Galbally says. To measure emissions of these air pollutants from grass, scientists from Monash and CSIRO set up a transparent chamber in a grass paddock in Gippsland, south-eastern Victoria. Over two years, the scientists collected and analyzed gases released by the grass to learn how emissions are affected by variations in temperature and light intensity, and by drought. Although grasslands and pastures cover a quarter of the Earth's land surface, this study is one of the first of emissions from grass and clover. "Emissions from grass are at their greatest in warm weather and at around midday, when sunlight is most intense," says Galbally. "No gases are released at night." Wayne Kirstine from the Gippsland campus of Monash University conducted the research with Galbally. Kevin D. Kephart Associate Professor of Plant Science Plant Science Department South Dakota State University Brookings, SD 57007 email: kkephart@abs.sdstate.edu Tel: (605) 688-4751 FAX: (605) 688-4452