Rethinking Biofuel Yields

According to new research from Michigan State University (MSU), focusing solely on biomass yield comes at a high price. Looking at the big picture allows other biofuel crops, such as perennial grasses to score higher than corn, as viable alternatives for biofuel production. The research was published in the recent issue of Proceedings for the National Academy of Sciences.

GLBRC / KBS LTER cellulosic biofuels research experiment; Photo“We believe our findings have major implications for bioenergy research and policy,” said Doug Landis, MSU entomologist and one of the paper’s lead authors. “Biomass yield is obviously a key goal, but it appears to come at the expense of many other environmental benefits that society may desire from rural landscapes.”

Landis and a team of researchers from the Great Lakes Bioenergy Research Center compared three potential biofuel crops: corn, switchgrass, and mixes of native prairie grasses and flowering plants. They measured the diversity of plants, pest and beneficial insects, birds and microbes that consume methane, a greenhouse gas that contributes to climate change. Methane consumption, pest suppression, pollination and bird populations were higher in perennial grasslands.

In addition, the team found that the grass crops’ ability to harbor such increased biodiversity is strongly linked to the fields’ location relative to other habitats. For example, pest suppression, which is already higher in perennial grass crops, increased by an additional 30 percent when fields were located near other perennial grass habitats.

This suggests, says Landis, that in order to enhance pest suppression and other critical ecosystem services, coordinated land use should play a key role in agricultural policy and planning. “With supportive policies, we envision the ability to design agricultural landscapes to maximize multiple benefits.”

Landis points out that rising corn and other commodity prices tempt farmers to till and plant as much of their available land as possible. This includes farming marginal lands that produce lower yields as well as converting acreage set aside for the Conservation Reserve Program, grasslands and wetlands.

“Yes, corn prices are currently attractive to farmers, but with the exception of biomass yield, all other services were greater in the perennial grass crops,” Landis said. “If high commodity prices continue to drive conversion of these marginal lands to annual crop production, it will reduce the flexibility we have in the future to promote other critical services like pollination, pest suppression and reduction of greenhouse gasses.”

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