Challenging the notion that urban “green” spaces help counteract greenhouse gas emissions, new research has found — in Southern California at least — that mowing and other lawn maintenance emit almost as much or more greenhouse gases than the well-tended grass extracts from the air.
Turfgrass lawns 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 new 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.
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.
“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,” says Amy Townsend-Small, Earth system science postdoctoral researcher at University of California, Irvine. Townsend-Small is the lead author of the study, which has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union (AGU).
The research results are important to greenhouse gas legislation being negotiated, Townsend-Small says. “We need this kind of carbon accounting to help reduce global warming,” the lead author says. “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 analyze grass in four parks near Irvine, Calif. Each park contains two types of turf: ornamental lawns (picnic areas) that are largely undisturbed, and athletic fields (soccer and baseball) that are trampled a lot and replanted and aerated frequently.
The researchers took and 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 shows that nitrous oxide emissions from lawns are 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 calculate, releases about almost as much or more carbon dioxide than the plots can take up, depending on management intensity. Athletic fields fare even worse, because — due to soil disruption by tilling and resodding — they don't trap nearly as much carbon as ornamental grass but require 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 concludes.
The UCI study was supported by the Kearney Foundation of Soil Science and the U.S. Department of Agriculture.Notes for Journalists
The 22 January paper altered by the Correction can be downloaded.
Or, you may order copies of the Correction and/or the original paper by emailing your request to Peter Weiss at email@example.com, or Cathy Lawhon at firstname.lastname@example.org. Please provide your name, the name of your publication, and your phone number.
Neither the Correction nor the original paper are under embargo.News radio
Arctic melt ponds form when meltwater clogs ice pores
24.01.2017 | University of Utah
New Study Will Help Find the Best Locations for Thermal Power Stations in Iceland
19.01.2017 | University of Gothenburg
A Swedish-German team of researchers has cleared up a key process for the artificial production of silk. With the help of the intense X-rays from DESY's...
For the first time ever, a cloud of ultra-cold atoms has been successfully created in space on board of a sounding rocket. The MAIUS mission demonstrates that quantum optical sensors can be operated even in harsh environments like space – a prerequi-site for finding answers to the most challenging questions of fundamental physics and an important innovation driver for everyday applications.
According to Albert Einstein's Equivalence Principle, all bodies are accelerated at the same rate by the Earth's gravity, regardless of their properties. This...
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
24.01.2017 | Earth Sciences
24.01.2017 | Life Sciences
24.01.2017 | Physics and Astronomy