University of California

Posts Tagged: greenhouse gas

A home garden can help reduce greenhouse gas emissions

A UC Santa Barbara study concluded that planting a home garden can cut carbon emissions to the atmosphere. However, if gardening isn't done right, it could actually contribute to greenhouse gas emissions, reported Nathanael Johnson on

The article looked at five factors that impacted greenhouse gas emissions in home gardens:

  1. Reduction of lawn area due to replacement by the garden
  2. Reduction of vegetables purchased from the grocery store
  3. Reduction in the amount of greywater sent to treatment facilities due to diversion to irrigate the garden
  4. Reduction in amount of household organic waste exported to treatment facilities due to home composting
  5. Organic household waste is composted for use in the garden

The abstract of the research article, written by David Cleveland, sustainable food systems professor in the Department of Geography, said:

"We found that (gardens) could reduce emissions by over 2 kg CO2e kg−1 vegetable, but that results were sensitive to the range of values for the key variables of yield and alternative methods for processing household organic waste."

In his Grist story, Johnson provided key points from the research that can help ensure the home garden is climate smart:

  • The main reduction from gardening comes from diverting food waste from the landfill, where it rots and emits methane and nitrous oxide. Food waste must be properly composted to prevent the emissions.
  • Planting a garden then forgetting about it ends up emitting more greenhouse gases than if you never started.

The article suggests that Californians contact their local UC Master Gardener program for assistance in properly managing a home vegetable garden. Johnson spoke to Kerrie Reid, the UC Cooperative Extension environmental horticulture advisor in San Joaquin County.

"Reid doesn't abandon her plants midway through summer, and she doesn't over-plant and then end up throwing out dozens of thigh-thick zucchinis," Johnson wrote. "Sure, when the cucumbers peak, there are more than she and her husband can eat, she confesses, but they share with their neighbors. The neighbors also come over to harvest herbs from the sidewalk."

The article said readers can find their own version of Reid by looking up a local UC Cooperative Extension Master Gardener program.

UCCE Master Gardeners of Santa Clara County conduct sustainable gardening and hands-on workshops for the public.
Posted on Wednesday, September 21, 2016 at 4:03 PM
Tags: climate change (43), garden (38), greenhouse gas (4)

San Joaquin Valley row crop growers help control greenhouse gases

Jeff Mitchell, left, presents research results at a UC ANR West Side Research and Extension Center field day.
Reporter Dennis Taylor of the Visalia Times-Delta wrote about research results recently published by UC Agriculture and Natural Resources scientists that may allow farmers to be part of carbon cap-and-trade agreements.

Taylor interviewed lead researcher Jeff Mitchell, UC ANR Cooperative Extension specialist and chair of the UC ANR Conservation Agriculture Systems Innovation Center.

Long-term research by UC ANR has documented the capacity for farmland in the San Joaquin Valley managed with certain conservation practices to sequester carbon, results that could give farmers a seat at the carbon trading table, the article said. The study was published this month in the Agronomy Journal.

"We're reducing the atmospheric load of carbon dioxide, a greenhouse gas that plays an important role in global warming," Mitchell said. "Proving a stable storage location for carbon could allow agriculture to be part of future cap-and-trade programs."

The ANR news release on the research was also picked up by the Central Valley Business Times, California Political Review and the Red Bluff Daily News.


Posted on Thursday, February 19, 2015 at 10:13 AM

Pollution regulations stymie dairy electricity generation

For Central Valley dairies, conflicting laws are making it hard to generate green electricity from dairy waste, according to an article this week in the Los Angeles Times.

In order to reduce emissions of methane - a greenhouse gas - some dairy operators have installed methane digesters that convert the methane into electricity.

However, the process produces nitrogen oxides (NOx), which react with volatile organic compounds to create ozone, a significant air pollution problem in the San Joaquin Valley. NOx levels for the valley, a region with air pollution among the most severe in the country, is set by federal officials and enforced by the San Joaquin Valley Air Pollution Control District.

The district is requiring expensive modifications on digesters, which in some cases shuts the equipment down altogether. Air district officials told the LA Times they're just doing their jobs. "Combating smog, not climate change, is the agency's mission," Times reporter P.J. Huffstutter wrote.

Modesto dairy operator John Fiscalini spent hundreds of thousands of dollars on a catalytic converter and other filtering equipment to meet the air district's limit of 11 parts per million of NOx for his digester system.

UC Davis Cooperative Extension animal scientist Frank Mitloehner told the Times that works out to equal the emissions of 26 cars for every 1,000 cows.

"They have a point. I want clean air," Visalia dairy farmer Ron Koetsier was quoted in the story. "But it doesn't make financial sense for me keep doing this. I don't see how they can turn methane gas into electricity in California, given these rules."

Dairy cow in California.
Dairy cow in California.

Posted on Wednesday, March 3, 2010 at 9:57 AM

UC helps Marin dairy operators clear the air

UC Cooperative Extension provided Marin ranchers and dairy operators exposure at a two-hour workshop Feb. 2 to the latest conservation practices that can help the agriculture industry reduce its environmental impacts and increase farm and ranch energy efficiency.

In addition to local farmers, reporter Rob Rogers was at the event collecting information for an article published in the Marin Independent Journal yesterday.

Rogers reported that cows produce a smaller percentage of greenhouse gases in the United States and Europe than in other nations, where farming is a larger part of the economy, and where it's practiced less efficiently. According to the United Nations, livestock produce about 18 percent of the world's greenhouse gasses. In the U.S., livestock is responsible for just 5.8 percent of total greenhouse gas emissions.

Workshop speaker Frank Mitloehner, UC Davis air quality specialist, said research shows that it is cows - not waste storage lagoons - that emit most methane and nitrous oxide on dairies.

"Lagoon waste is so heavily diluted that it's a smaller factor than fresh waste," Mitloehner was quoted in the story.

He offered solutions that may not sit well with organic producers:

  • Produce more milk with fewer cows by increasing efficiency.

  • Cut back on grass-fed cattle, which, because of extra roughage, produce more methane.

Albert Strauss, an organic dairy farmer who also spoke at the meeting, noted that reducing cow emissions is only part of the environmental picture. One option for reducing dairy emissions is converting waste into energy with a methane digester. Using this technology, the Strauss operation meets its own energy needs and will soon be selling extra energy back to PG&E, the article said.


Posted on Thursday, February 4, 2010 at 10:55 AM
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