Error in University Turf Study Voids Negative Conclusion About Turf Grass

I read a turf study that came came out of the University of California Irvine that just did not make sense to me, so I did some homework.

Basically, UCI came to the conclusion that urban turf contributes to global warming. Now, I am a user of lawns, vendor of turf maintenance products and we support many companies that maintain turf. But, for over 25 years I have promoted sensible use of all plants in the landscape, including turf grasses. You will not find a single landscape in my portfolio that is wall to wall grass. Therefore, I feel I am unbiased by either the promoters of grass and sod products or those adamant that artificial turf or rock is the way of the future. Come to think of it, the artificial turf product manufacturers should be more wary of this study than the natural grass industry.

First is the rebuttal press release-

Monday, February 22,2010
Error in Turf Study Voids Conclusion

The University of California, Irvine, has acknowledged a computation error in their 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 the findings were found to be based on incorrect data.

Upon review of the report, various flaws were discovered. The carbon from fuel consumption was multiplied by 12, one too many times, to convert from monthly to annual data. Another significant math error was made in computing the carbon consumed during mowing. When the computations were corrected, it was found that turfgrass actually is a net sequesterer of carbon dioxide, reversing the conclusions of the original report.

“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. We need to focus on the right plant in the right place and on management practices that maximize the environmental benefits potential of turfgrass,” said Kris Kiser, executive vice president of Outdoor Power Equipment Institute (OPEI).

OPEI also noted that the UCIrvine study did not acknowledge the dramatic reductions of emissions and fuel use profile for today’s gasoline and diesel equipment, nor did the study disclose what model equipment and corresponding fuel use numbers were used.

Here is the original release-

Be careful not to get this erroneous information into the hands of the wrong people.

Urban ‘Green’ Spaces May Contribute To Global Warming, UCI Study Finds

February 22, 2010

Irvine, CA – Dispelling the notion that urban “green” spaces help counteract greenhouse gas emissions, new research has found – in Southern California at least – that total emissions might be lower if lawns did not exist.

Turfgrass lawns help remove carbon dioxide from the atmosphere through photosynthesis and store it as organic carbon in soil, making them important “carbon sinks.” However, greenhouse gas emissions from fertilizer production, mowing, leaf blowing and other lawn management practices are similar to or greater than the amount of carbon stored by ornamental grass in parks, a UC Irvine study shows. These emissions include nitrous oxide released from soil after fertilization. Nitrous oxide is a greenhouse gas that’s 300 times more powerful than carbon dioxide, the Earth’s most problematic climate warmer.

“Lawns look great – they’re nice and green and healthy, and they’re photosynthesizing a lot of organic carbon. But the carbon-storing benefits of lawns can be counteracted by greenhouse gas emissions,” said Amy Townsend-Small, Earth system science postdoctoral researcher and lead author of the study, forthcoming in the journal Geophysical Research Letters.

The research results are important to greenhouse gas legislation being negotiated. “We need this kind of carbon accounting to help reduce global warming,” Townsend-Small said. “The current trend is to count the carbon sinks and forget about the greenhouse gas emissions, but it clearly isn’t enough.”

Turfgrass is increasingly widespread in urban areas and covers 1.9 percent of land in the continental U.S., making it the most common irrigated crop.

In the study, Townsend-Small and colleague Claudia Czimczik analyzed grass in four parks near Irvine, Calif. Each park contained two types of turf: ornamental lawns (picnic areas) that are largely undisturbed, and athletic fields (soccer and baseball) that are trampled and replanted and aerated frequently.

The researchers evaluated soil samples over time to ascertain carbon storage, or sequestration, and they determined nitrous oxide emissions by sampling air above the turf. Then they calculated carbon dioxide emissions resulting from fuel consumption, irrigation and fertilizer production using information about lawn upkeep from park officials and contractors.

The study showed that nitrous oxide emissions from lawns were comparable to those found in agricultural farms, which are among the largest emitters of nitrous oxide globally.

In ornamental lawns, nitrous oxide emissions from fertilization offset just 10 percent to 30 percent of carbon sequestration. But fossil fuel consumption for management, the researchers calculated, released almost as much or more carbon dioxide than the plots could take up, depending on management intensity. Athletic fields fared even worse, because – due to soil disruption by tilling and resodding – they didn’t trap nearly as much carbon as ornamental grass but required the same emissions-producing care.

“It’s unlikely for these lawns to act as net greenhouse gas sinks because too much energy is used to maintain them,” Townsend-Small concluded.

Previous studies have documented lawns storing carbon, but this research was the first to compare carbon sequestration to nitrous oxide and carbon dioxide emissions from lawn grooming practices.

The UCI study was supported by the Kearney Foundation of Soil Science and the U.S. Department of Agriculture.

SOURCE: University of California

So, math errors again factor into the global warming debacle.

What are your thoughts?

Frank