Its official. Turf tested positive as a carbon sequester in three different studies. One study found turf sequestrates between four to seven times as much carbon as a modern mower discharges. The others were less clear on amounts, but all three studies show turf could be one of the biggest crops when it comes to sequestrating carbon, based on the sheer volume of land under turf cultivation. This is great news for golf courses and other sporting facilities. The days of turf professionals cowering to environmentalists over negative press must cease. It is time we fight back with science on our side.
Turf is one of the best filters for heavy metals. Fifteen square metres of lawn produces enough oxygen for a person to breath, and turf is 20 degrees cooler than fake plastic grass on a 40 degree day and 30 degrees cooler than dark coloured concrete. The only bad thing they could really say about turf is that mowers pollute, and turf uses too much water. We now have three studies that declare turf is carbon positive, and two studies that show warm season turf uses less water than many ornamental plantings. Unfortunately many less reputable environmentalists will not let science and facts get in the road of a compelling yet misleading media beat up. But if turf professionals all over the country let their clients know about this new research, and how turf is such a good guy, turf will get the good wrap it deserves.
Studies and analysis
“Technical Assessment of the Carbon Sequestration Potential of Managed Turfgrass in the United States” is a research report by Dr. Ranajit (Ron) Sahu. The key findings in this report are that an average maintained lawn sequestrates four times the carbon compared to the carbon output of a typical modern lawn mower used in maintaining the lawn. If one compares a well-managed lawn to a poorly managed lawn or unmanaged grasslands, the net carbon intake of a well-managed lawn is five to seven times higher than the carbon output of mowing.
Not surprisingly, certain maintenance methods resulted in higher carbon benefits. The research showed the largest amount of carbon intake occurs with the recycling of nitrogen contained in grass clippings; meaning, leave clippings on the ground to break down and recycle. The study also found that the carbon sequestration of turfgrasses can be maximised by measures such as cutting regularly and at the appropriate height, feeding with nutrients left by grass clippings, watering in a responsible way, and not disturbing grass at the root zone – all these measures help grass actively pull pollutants from the air, creating a greater carbon benefit. The full paper can be found at http://multivu.prnewswire.com/broadcast/33322/33322cr.pdf
Another research paper delved deeper into all inputs that go into maintaining lawns, including higher than average fertiliser and water inputs. The controversial study conducted by the University of California, Irvine made critical errors in its calculation. These were big errors that totally changed the outcome of the research. Numerous peer reviews did not pick up the mistakes. Firstly, it presented the data with the incorrect information, and said that turf was a net polluter. Luckily vigilant people in the turf industry picked these mistakes up, and contacted the university. Soon after, it issued an updated version of the paper.
The University of California, Irvine acknowledged a computation error in its recently released study entitled, “Carbon Sequestration and Greenhouse Gas Emissions in Urban Turf.” The initial findings blamed common turf grass for contributing to global warming, but it was discovered the findings were based on incorrect data from other experts.
Upon review of the report, various flaws were highlighted. When the computations were corrected, it was found that turfgrass is actually a net sequester of carbon dioxide, reversing the conclusions of the original report, although the calculations regarding the amount of fertiliser used in the report were still very high compared to what other research has found. A study by Scotts showed fertiliser use is far less than was assumed in this study.
The Irvine study also wrongly assumed all lawns are irrigated regularly. “The grass in your backyard is working hard to keep us cool, soak up carbon, capture particulates, produce oxygen, capture rain water and reduce run-off,” says Kris Kiser, executive vice president of Outdoor Power Equipment Institute (OPEI), an international trade association. OPEI also noted that the University of California, Irvine study did not acknowledge the dramatic reductions of emissions and fuel use profile for today’s petrol and diesel equipment, nor did the study disclose what model equipment and corresponding fuel use numbers were used.
Other research shows it also over estimated the amount of fertiliser used on lawns. Still, when the study was revised with correct data, it did show that turfgrass is a net carbon sequesterer. Unfortunately the report got more publicity when the environmentalist websites and many media organisations thought turf was a polluter, and very little when other researchers blew the whistle and realised the mistake, and found that turf is carbon positive.
A paper by Gina Nicole Zirkle, Environment and Natural Resources, Ohio State University, Columbus, titled, “The Potential for Soil Organic Carbon Sequestration in Home Lawns” suggested that results support the conclusion that lawns are a positive net sink for atmospheric CO2 under all evaluated levels of management practices. Further the paper suggested that in an average home landscape, trees sequestrate about seven to 14 per cent of the carbon; shrubs about one to two per cent of the carbon; and turf approximately 80 to 90 per cent of the carbon. It also suggested that when a tree dies, most of the carbon escapes back to the atmosphere, where as turf generally keeps the carbon in the soil. This paper can be found at http://a-c-s.confex.com/crops/2009am/webprogram/Paper52288.html or http://etd.ohiolink.edu/send-pdf.cgi/Zirkle%20Gina%20N.pdf?osu1267189156
Communication
So far, three scientific studies show turf is carbon positive. So how do we get this message across? Simple. If many green keepers make a simple poster based on the Dr. Rmajit study, saying that turf sequestrates four times the amount of carbon compared to the emissions of a modern lawn mower, and display it in as many places as possible around their sporting facilities, large numbers of people will get the message that turf is a good guy.
It would be even better if a turf association made a poster that people could put up. The benefits for the sporting facilities would be extremely positive. Governments, lobby groups, and the facility users would all see turf in a different way. The turf industry now has research it can use to lobby governments and hopefully get a better deal for turfgrass facilities. Based on this recent research, turf is one of the largest carbon positive resources in Australia and we should be lobbying to have any carbon scheme recognise this.
People who criticise turf will still point to turf needing lots of water. Research shows turf is one of the most water wise plants. A study by the University of Western Sydney, showed that warm season turf has watering requirements about the same as native plants, and turf accounted for much less water than exotic gardens.
A recent US study conducted in dry, hot Texas showed that warm season turf can survive on no water in hot summers for 60 days and return to health within a month or two when the water is reinstated. In another comprehensive study, University of Florida researchers carefully documented water use in a buffalo grass (Stenotaphrum secundatum) lawn and an adjacent native (to the United States) mixed species landscape. In year one the lawns used significantly more water than the surrounding native landscape. In year two, the turf still used more than the adjacent shrubs although at a much lower rate than year one. But by year three there was no difference between the lawn and the plants. In year four the plants used more than double the amount of water compared to the turf. As turf professionals you know this through instinct. As turf ages, it needs far less water. The reference to this study is: Park, DM and Cisar, JL 2005, “Documenting water use from contrasting urban landscapes – turf vs. ornamentals”. It was published in TPI Turf News, May/June 2005: pp. 38-42.
The research listed in this article supports the notion that turf is one of the most environmentally friendly urban planting systems available. As an industry, we need to communicate this to the public, or suffer in silence the bad press that turf often receives from uninformed commentators.
Author:
Todd Layt
