Can Perennial Bioenergy Crops Help Sequester Carbon?

by Krista Eastman (Great Lakes Bioenergy Research Center) In an article published last summer in Science, researchers at the Great Lakes Bioenergy Research Center (GLBRC) reported on ten years of work assessing the potential climate benefit of producing dedicated bioenergy crops such as switchgrass, poplar, or restored prairie. The mood? Cautiously optimistic.

According to GLBRC scientist and University of Wisconsin-Madison professor of agronomy Randy Jackson, one of those factors will be determining how and where bioenergy crops are capable of enhancing carbon storage in soils and helping to stabilize the climate. "There is this assumption that if we plant native prairie grasses it's automatically going to lead to carbon sequestration in the soil," says Jackson. "But what we're seeing so far is that sequestration can be site-specific."

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Jackson's most recent research examines how grassland composition - specifically the ratio of different types of grasses - and underlying soil characteristics affect carbon accumulation. READ MORE

UW–Madison researchers explore the future of bioenergy crops in Wisconsin (Great Lakes Bioenergy Research Center)

Carbon Farming Works. Can It Scale up in Time to Make a Difference? (Civil Eats)

Can Dirt Save the Earth? (New York Times)

Excerpt from Great Lakes Bioenergy Research Center: Randy Jackson, a UW-Madison professor of agronomy who holds meetings with farmers and decision-makers as part of his research on sustainable agricultural systems, says current policies and prevailing market forces keep a tight hold on our current cropping landscape.

“To get started [in farming], you’re going to need a loan, and the bank is not likely to give you a loan unless you have a business plan based on corn and soybeans,” says Jackson. He also points out that some practices that exacerbate runoff pollution, such as planting row crops next to streams, are also the result of economic calculations. “It allows farmers to keep that land zoned agriculture, which means lower taxes.”

But what’s missing from our current approach to land management, Jackson argues, is a means of accounting for the social and environmental costs and benefits of various cropping systems. Jackson, Gratton, and other UW–Madison scientists are looking to measure those costs while exploring new and collaborative ways of making our cropping systems serve farmers as well as the people, plants, and animals that depend on healthy ecosystems.

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Jackson defines marginal lands as “land that isn’t great for growing crops because it’s exceedingly wet, exceedingly dry, exceedingly rocky, or exceedingly steep,” or “land where the income from your products doesn’t cover the cost of production.”

GLBRC studies have shown that growing native perennial species on marginal lands not only avoids competition with food production, but also provides the greatest potential for climate mitigation and biodiversity benefits. In their discussions with farmers on marginal land use, Jackson and his team also found that farmers are more interested in planting perennial crops in marginal areas that are not otherwise producing well for them.

And yet to facilitate a more large-scale adoption of marginal land perennialization, Jackson says there’s a need for “decision support tools,” or software that can help farmers make the kind of ecologically sound cropping choices that will also earn them money.

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Farmer-led solutions

To that end, Gratton has developed a web-based decision support tool called SmartScape™. After entering in simple initial data points about your land, you receive a readout of how the land is performing across a range of environmental outcomes. From this you can see where “hot spots” are located on the landscape – these might be acreage near streams or in hilly sections – where planting perennial crops would have a disproportionately positive or negative effects on the ecosystem.

“There are some places where the land is super productive and it just doesn’t make sense to plant switchgrass,” says Gratton, “but there are other places on the land where farmers lose money growing corn. Moreover, we know that perennial grasses can be used as buffer strips to stop the flow of runoff and nutrients.”

“Decision support tools allow farmers, landowners, and policymakers to sit around a table and say, ‘if I paint the landscape like this and put switchgrass over here, What happens to carbon?, What happens to nitrogen?, What happens to my profit?, How is my neighbor affected?,’” says Jackson. “And if everyone is sitting around the table having this discussion about tradeoffs and synergies in what we call ecosystem services [e.g., methane consumption, pest suppression, or pollination], then it can help people arrive at what we would consider to be sustainable, enduring solutions.”

One of the advantages of the SmartScape™ model is that it can be scaled up to a regional level or scaled down to a small watershed. One complication of focusing on hot spots, however, is that they may not be uniformly distributed throughout a watershed. That means one farmer might have hot spots while his neighbor has none, a factor with the potential to complicate group decision-making. And yet, according to the researchers, early feedback from land managers at county and state agencies has been encouraging. READ MORE includes Interactive Graphics about comparative carbon, nitrogen and phosphorus cycles and about crop choices.