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Green Times – Sequestering Carbon, Microbes, Veg Gardens + Diet – Feb. 21, 2013

Posted by struscott | February 21, 2013

WSU Scientists Unearth Potential of Climate Friendly Farming and Carbon Sequestration

Farm management practices such as crop rotation and tillage can provide a real—though modest—contribution to carbon sequestration in the Pacific Northwest. This is the conclusion suggested by two recently published studies by WSU researchers in the Department of Crop and Soil Sciences and the Department of Biological Systems Engineering.

Soil plays an essential role in the complex global carbon cycle. To understand this, consider that globally, carbon moves between the land (including soil, plants, trees), the atmosphere, and the oceans. Throughout the cycle, carbon is stored in various places in the system, including living plants, fossils, the deep ocean, the atmosphere – and soil, where it may be stored in residues of plants and animals, as well as in inorganic minerals. Stored carbon can be released into the atmosphere through natural process (such as microbes decomposing organic matter) as well as human activities (fossil fuel burning). Carbon stored in soil accounts for roughly three times the amount stored in the atmosphere and more than four times the carbon stored in living plants and trees.

The carbon cycle, along with similar cycles for water and nitrogen, contributes to an intricate web of interactions that are crucial to sustaining life on the planet. Change in one part of the system can have significant and sometimes unexpected impacts in another part. For example, a relatively small change in the amount of carbon stored in soil (for instance, due to tillage) could significantly influence greenhouse gas concentrations in the atmosphere.

Simplified representation of the global carbon cycle. Changes are measured in gigatons of carbon per year (GtC/y). Numbers in parentheses refer to stored carbon pools. Yellow numbers refer to natural carbon emissions. Red indicates carbon from human emissions. Graphic courtesy of the U.S. Department of Energy Genomic Science Program, http://genomicscience.energy.gov.
Simplified representation of the global carbon cycle. Changes are measured in gigatons of carbon per year (GtC/y). Numbers in parentheses refer to stored carbon pools. Yellow numbers refer to natural carbon emissions. Red indicates carbon from human emissions. Graphic courtesy of the U.S. Department of Energy Genomic Science Program, http://genomicscience.energy.gov.

How does carbon storage in agricultural soil work? Basically, the more productive the soil—that is, the more plant life or biomass it can support—the more carbon the soil can potentially store (at least until it reaches a state of equilibrium, at which point the soil is holding all the carbon it can). Soil productivity is influenced by several key factors including precipitation, fertilization, crop rotation, the use of perennial crops, organic soil amendments, and tillage. Tillage reduces the amount of stored carbon by exposing crop residue to air. Once exposed, the carbon in the crop residues combines with oxygen, thus releasing CO2 into the atmosphere. That’s why evaluating the impact of alternative practices such as reduced-till and no-till farming is of great interest to scientists, growers, and policy developers alike.

According to Georgine Yorgey of the WSU Center for Sustaining Agriculture and Natural Resources (CSANR), it’s difficult to produce an exact number for the amount of carbon that can be stored in Pacific Northwest soils, but the “modest” contribution is in the range of less than one percent of Washington’s total greenhouse gas emissions. Nonetheless, the promise of soil carbon sequestration is real enough (and the situation serious enough) to warrant further investigation. While this is a small fraction of the region’s greenhouse gas footprint, storing that much carbon in our soils would make a substantial contribution to the sustainability of regional agriculture.

Given the complexity of the interrelated processes at work with agriculture and climate disruption, the tradeoffs between different management practices must be evaluated. For example, using nitrogen fertilizer can increase nitrous oxide (a potent greenhouse gas) emissions and thus counteract the positive benefit of soil carbon sequestration, while including legumes in a cropping system requires less nitrogen fertilizer but produces less biomass and therefore stores less carbon than cereal-based crops. And then again, organic farming systems tend to be more dependent on tillage to control weeds, and tilling soil requires fossil fuels and releases stored carbon.

Soil from an annual wheat field (left) compared to that from a perennial wheatgrass field (right). Perennial crops can store more soil carbon than annual crops. Photo courtesy of The Land Institute.
Soil from an annual wheat field (left) compared to that from a perennial wheatgrass field (right). Perennial crops can store more soil carbon than annual crops. Photo courtesy of The Land Institute.

Chad Kruger, director of CSANR director, cautions that “before we promote a given system or practice as ‘good for the climate’ we need to more fully quantify the total impact.” Science-based information will be critical for developing policy, carbon markets, and sound farm management practices. Studying soil carbon storage offers plenty of opportunity to contribute to the evolving science behind the relationship between agriculture and climate change.

More to explore

This article was inspired by these resources:

“Soil carbon sequestration in the dryland cropping region of the Pacific Northwest” by Brown and Huggins 2012; available online at http://bit.ly/YtFHs4.

“Carbon storage and nitrous oxide emissions of cropping systems in eastern Washington: A simulation study” by Stöckle et al. 2012. Available online at http://bit.ly/UzmpUr.

Webinars on PNW Agriculture and Climate Change including “Soil Carbon Dynamics and Climate Change Mitigation in the Inland Pacific Northwest” by Georgine Yorgey, WSU CSANR. Available online at http://bit.ly/PXldrv.

Perspectives on Sustainability blog post “Can soil carbon storage really make a difference to our climate? Do we have the right data to answer?” by Chad Kruger, WSU CSANR. Available online at http://bit.ly/12Z6ZfF.

Check out a short video on no-till farming practices and how they can retain significant amounts of carbon in the soil, which is beneficial both for crops and the atmosphere: http://bit.ly/Y3zDGQ.

WSU offers numerous educational avenues for those interested in exploring the interplay of climate and agriculture. The departments of Crop and Soil Sciences and Biosystems Engineering are good places to start your exploration.

–Sylvia Kantor, with additions by Chad Kruger and Brian Clark

Natural Soil Antibiotics Offer Alternative to Farm Chemicals

Several naturally occurring antibiotics can control root disease and promote crop health, offering an alternative to chemicals used in farming.

Linda Thomashow, a U.S. Department of Agriculture - Agricultural Research Service geneticist and adjunct professor in plant pathology at WSU.
Linda Thomashow, a U.S. Department of Agriculture – Agricultural Research Service geneticist and adjunct professor in plant pathology at WSU.

“All you have to do is make your microbial community happy,” said Linda Thomashow, a U.S. Department of Agriculture – Agricultural Research Service geneticist and adjunct professor in plant pathology at WSU. Thomashow said the door is open for scientists, farmers, and industry to develop commercial applications of root bacteria that can protect the rest of the plant. Thomashow was speaking to fellow scientists and media at the American Association for the Advancement of Science meeting in Boston.

But typically, science has concentrated on treating the above-ground parts of a plant, she said. “So much less is understood about the plant mechanics for defense that are available underground.”

In recent years, Thomashow said, the tools of molecular biology have helped scientists understand the microbial and molecular workings of bacteria in the rhizosphere, the layer of soil next to roots, including how antibiotics there can suppress plant diseases. “They are a first line of defense,” she said.

Certain bacteria produce antibiotics that protect crop plants.
Certain bacteria produce antibiotics that protect crop plants.

One particular disease, Take-all, causes more than $1 billion per year in losses by rotting roots and depriving plants of water and nutrients. It’s often found in soils that are continuously replanted in wheat, whose money-making potential discourages farmers from planting alternative crops that might break disease cycles.

In some areas of eastern Washington, said Thomashow, farms have seen several decades of continuous wheat. Those same soils have in turn seen high densities of the bacterium Pseudomonas fluorescens producing a compound called DAPG that can suppress the Take-all fungus. Such beneficial bacteria create what are called “suppressive soils.” In a variety of circumstances, said Thomashow, they help control soilborne pathogens with minimal use of commercial fungicides and other chemicals. It should be possible to get similar results with a commercially available soil amendment if scientists, industry members, and farmers rise to the challenge and expense of bringing a living thing to market.

“If you balance that against the expense of developing a new chemical, it really doesn’t cost any more,” she said, “and it’s a sustainable alternative to the use of chemicals.”

Learn more about Take-all at http://bit.ly/15qn2CW. Learn more about how plant pathologists are discovering alternatives to chemical pest and disease control by visiting the WSU Department of Plant Pathology website at http://plantpath.wsu.edu/.

–Eric Sorensen

Eat Your Veggies: WSU Master Gardener Program Helps Residents Grow Own Vegetables

Rebecca Branderhorst
Rebecca Branderhorst

Rebecca Branderhorst went a little crazy in her vegetable garden last spring. The Longview, Wash., resident planted pole green beans, Oregon pea pods, lima beans, three kinds of lettuce, kale, Swiss chard, carrots, bunching onions, white Spanish onions, chives, celery, cilantro, and beets. All of it in a single 4-by-8-foot box. By mid-summer, Branderhorst’s garden looked like a mini-jungle of edible delights.

But that kind of enthusiasm was what WSU Extension’s Gary Fredricks wanted to see. He started a new program last year in Cowlitz County that promotes local food production through vegetable gardening while helping people financially or physically challenged to raise their own produce.

“Home VEG (Vegetable Educational Garden) removes some of the barriers that stop people from starting a garden,” Fredricks said. “It’s a great success. All 10 families that participated grew great gardens, learned from their mistakes, and expect to produce even more in 2013.”

The program pairs WSU Master Gardener volunteers with local residents who apply for the program and are accepted. The Master Gardeners build raised beds and provide soil, seeds, plant starts, and advice. Participating growers maintain the garden for three years, attend a class on vegetable gardening, and do all the work to maintain the garden.

For Branderhorst, the raised bed was the best part. She had knee replacement surgery in September 2011, effectively preventing her from digging in the dirt on her hands and knees. The bed had other benefits as well. “There were no slug problems, far fewer weeds, and with my knee replacement, the access to weeding, planting, and tending was so nice,” she said.

Branderhorst was so inspired by her experience that she planted root vegetables in her gardening bed over the winter, banking on Longview’s tendency toward rain for another chance to stock up her larder. “So far, it looks like some of them are doing okay,” she said. “I’ve got little potatoes out there that I hope to throw in a soup or stew.”

Barbara Byker of neighboring Kelso liked the raised beds for a different reason. “Living on dredge spoils [the sand, sediment, and debris from dredging that are transported to land to dry out], we have had poor results from previous gardens,” Byker said. “We planted corn, beans, peas, zucchini, lettuce, tomatoes, pumpkins, and yellow crook-neck squash. We ate better and enjoyed trying new veggies.”

Master Gardener mentors like Jon Griffin enjoyed helping program participants uncover their green thumbs. Griffin worked with Bob Griffith last year and found the Longview resident very willing to try new things—and learn that even one zucchini plant was too much.

“I can see the information Master Gardeners supply connects in a very important way with many members of our community,” Griffin said. “I think this program is a very helpful, healthy teaching program.”

Master Gardener Phyllis Hull, who worked with Longview’s Pam Atkinson, also appreciated helping others learn to grow their own food. But nothing beat the feeling Hull got when she visited Atkinson’s garden one day to take some pictures of her harvest.

“The garden was pretty well picked clean,” Hull said. “I asked Pam what happened to her vegetables. She proudly raised her head high and with a sly grin proclaimed, ‘I ate them.’ I was never as happy as I was for her that day. Her success and feeling of accomplishment were plastered all over her face–along with a little tomato juice.”

For details about the Home VEG program, contact Gary Fredricks at 360-577-3014, Ext. 3, or at garyf@wsu.edu.

—Nella Letizia

Upcoming Beekeeping Events

beesWSU beekeeping and queen-rearing workshops are coming up in June and July – and are filling up fast. Sweeten up your calendar by registering early for these workshops at http://bit.ly/apis-events-2013.

The queen-rearing workshops will provide an understanding of what it takes to raise high quality queen bees. Basic biology and methods of queen rearing will be presented in hands-on workshops. Beekeepers will be involved in the various steps: setting up cell builders, grafting, and establishing mating nuclei. A queen-right and a queen-less system will be demonstrated. Participants need to bring a bee veil and whatever protective clothing they are comfortable in. The queen-rearing workshops are being offered in both Pullman (June 12 and 13) and Mt. Vernon (July 19).

The WSU Beekeeping Short Course will run June 14 – 15 in Pullman. If you’re curious about what this short course has to offer you, check out this short video from a related program: http://bit.ly/VAq2ei.

Got Credit?

The HumanLinks Foundation, a non-profit organization dedicated to systematic improvements in education, healthcare and sustainable agriculture, is offering a micro-loan program to sustainable farmers to help strengthen the Washington state farming community.

Beginning in March 2013, HumanLinks Foundation will enable credit access to farmers who may not have been able to secure a loan through a conventional bank. Partnering with Banner Bank, the foundation will give local, sustainable farmers the ability to borrow funds at a favorable interest rate of three percent (3%) for up to two years. The minimum loan size is $2,500 and the maximum loan size is $25,000.

Please email nancy@humanlinksfoundation.org or call 206-830-0083 for more information.