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Home > Solutions > Fall 2012 > Biochar, Bio-benefits?

Biochar, Bio-benefits?

Researchers and master gardeners team up to evaluate the benefits of a sustainable biofuels system

By Becky Beyers

Julie Weisenhorn and Jason Hill.

It’s hard to tell just from looking at the three identical garden plots on the north end of campus that the soil they’re planted in might hold one of the key pieces in the “how can we make biofuels sustainable?” puzzle.

The plots are one of three initiatives assigned to Minnesota researchers as part of an eight-state, multi-institution, five-year research project known as CenUSA that’s funded by the U.S. Department of Agriculture and aimed at answering the big questions around biofuels. The goal is to evaluate the economic and environmental performance of the entire biofuel system—from what kinds of soils and grass varieties grow the best material for fuel, to farm safety, to transportation logistics, and to fuel production—ultimately to make recommendations for growing a sustainable biofuels industry. Researchers are also exploring what to do with the biochar, a byproduct of the pyrolysis process that turns biomass like switchgrass into fuel.

Jan Henry, Dave Knapp, and Mary Fitch.
Hennepin County Master Gardener Jan Henry, left, and Anoka County Master Gardeners Dave Knapp and Mary Fitch, at right, are among the volunteers who are maintaining, monitoring and evaluating the test plots.
Photos by David Hansen

That’s where the gardens come in. U of M Extension Master Gardeners, along with their counterparts in Iowa, will evaluate over the next four years how biochar as a soil amendment affects plants’ productivity and health. About 40 Minnesota gardeners are volunteering at three, 1,000-square-foot sites—on the St. Paul campus, at the Minnesota Landscape Arboretum in Chanhassen, and at Bunker Hills Regional Park in Andover. At each site, three identical plots have been planted with the same combination of flowering and vegetable plants—typical of a home garden—in the same layout. Each site includes a control plot with no biochar, one with a half-pound per square foot of biochar worked into the soil and another with a pound per square foot.

Master Gardeners’ contributions are not only planting and maintaining the sites, but evaluating biochar’s effects and ultimately making recommendations for whether and how biochar can best be used by consumers. This past summer was the first season, and three more will follow.

Before the sites were planted, the CFANS soil testing lab evaluated each local site’s soil, says Julie Weisenhorn (’02–M.Ag.), director of the U of M Extension Master Gardener program and an investigator on the project. While the Andover site was sandy, the Arboretum and St. Paul sites had more loamy soil. They also had different pre-planting challenges for the master gardeners, said Lynne Hagen, biochar project manager. The campus site had been home to a turfgrass research plot so has lots of thistles, the Arboretum site was covered in sod, and the Andover site was full of brush, trees and even poison ivy. All three had to be fenced to keep out deer or rabbits, Hagen said.

Weisenhorn, Hagen and Cindy Haynes, state coordinator for Extension Master Gardeners in Iowa, selected seeds based on how consumers would choose them for their own gardens, with an eye toward time to maturity, plant size and expected yield. Over the summer, the volunteer gardeners tracked and reported online how the plants in each plot performed – did it produce the blossoms or fruit of the expected size and quantity? How did the plant grow? Was it the size and hardiness expected, and what pest problems were encountered?

Along with reporting the results to the CenUSA team, the gardeners shared their findings with visitors to county fairs and the Minnesota State Fair. At this year’s State Fair, Weisenhorn said it’s too early to draw any final conclusions from the project so far, but the results look interesting for a few crops, particularly in sandy soils.

Master Gardeners provide a perspective that traditional researchers probably couldn’t, Weisenhorn says. “They can look at it as a home gardener would,” she says. “‘Would biochar be a good choice for my garden and planting containers?’ is the key question we’re trying to answer.”

Master gardener volunteers evaluating biochar's effect on soil and plants.
About 40 volunteers are maintaining and evaluating biochar's effect on soil and plants at sites in St. Paul, Andover and Chanhassen.  They're tracking identical plots with three different soil additions: no biochar, a half-pound per square foot of biochar worked into the soil, and a full pound per square foot.

Start-to-finish analysis

Jason Hill and Julie Weisenhorn.
Hill and Weisenhorn are part of a research team that involves scientists from eight institutions across the Midwest studying every aspect of biofuel production.

Jason Hill (’04–Ph.D., Plant Biological Sciences) and his team have a less visible but broad-ranging role in the multi-state project. Hill, an assistant professor in the Department of Bioproducts and Biosystems Engineering, and his team are charged with analyzing the possible environmental effects of a sustainable biomass system, using data from every stage and part of the project. Their work takes a life cycle perspective, providing a complete picture of important ecological issues like greenhouse gas emissions, water quality and wildlife habitat.

Even though they’ll be analyzing data captured during the project’s five-year life, it’s not a matter of simply waiting for that data to come in, Hill says. For example, his team worked with other groups to design the areas where perennial crops would be planted and tested, so that the data being collected as the crops are harvested, transported and turned into fuel would be most useful. “The idea is to bring us in right from the start so at the end we can make informed recommendations,” he says. “Our project leaders had the foresight to integrate analysis, rather than adding it as an afterthought.” Throughout the project, Hill and his co-principal investigator at Iowa State, along with graduate research assistants, will meet monthly to make in-progress assessments and adjustments.

Planting the un-plantable

CFANS scientists also have a role in a third question the project is seeking to answer: How do perennial crops affect the land and environment?

Graduate student Anne Sawyer is working with Department of Soil, Water, and Climate professors Carl Rosen and John Lamb to find the answers. They’re evaluating new varieties of grasses at several sites around Minnesota and will gather data about how the plants grow, how they affect their soil and water environments, how much biomass is harvested from each variety and whether the plants can withstand Minnesota winters. Identical field trials are happening in several other states across the upper Midwest.

Some of the plots will be used for demonstrations in which producers can evaluate the grasses firsthand; the others will be used to quantify biomass production in each variety as a function of different nitrogen fertilizer rates. This past summer, the team planted three kinds of grasses for a demonstration plot at a privately owned farm near Elko, and next year they’ll create a demonstration site at the Southwest Research and Outreach Center near Lamberton. Two more sites will be used for detailed research on six different kinds of grasses. This year, a detailed study plot was planted at the Sand Plain Research Farm in Becker. The other will be planted next year at the SWROC.

“The idea is that these would be marginal sites,” Sawyer says, the kind of land farmers typically now place in the Conservation Reserve Program, or land that is less productive for commodity crops due to erodibility and/or low fertility. Ideally, farmers would be able to profit from harvesting these grasses for biomass while the grasses prevent soil loss and improve water quality. The Elko site happens to be on rocky, hilly ground, and an early-summer 4.4-inch rainstorm washed out much of the first planting this year. Like everything else in the project, that experience was recorded and analyzed and will be factored in as the scientists and gardeners make recommendations.

“We’re learning as we progress,” Sawyer says. “That’s what makes this project so exciting—there are opportunities on so many levels.”

What's biochar?

Photo by Maddie Sieck, Iowa State University Bioeconomy Institute

Biochar is a byproduct of pyrolysis—the process by which grasses and other plant materials are turned into biofuel. It looks like grainy charcoal, but its tiny holes hold water and nutrients, which scientists believe could make it beneficial as a soil additive. It also may sequester large amounts of carbon, thus reducing greenhouse gases in the air.


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