Biofuel research looks beyond yield

Researchers from Michigan State University (MSU) have found that certain types and locations of biofuel crops have various benefits, and that it is unwise to focus solely on biomass yield. The team published their study in the journal Proceedings of the National Academy of Sciences.

“Producing bioenergy crops on marginal lands - farmland suboptimal for food crops - could help meet energy goals while minimising competition with food production,” the researchers stated. “However, the ecological costs and benefits of growing bioenergy feedstocks - primarily annual grain crops - on marginal lands have been questioned.”

With this in mind, entomologist Doug 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.

Image credit: MSU.

“We found that switchgrass and prairie plantings harboured significantly greater plant, methanotrophic bacteria, arthropod and bird diversity than maize,” the researchers said. “Although biomass production was greater in maize, all other ecosystem services, including methane consumption, pest suppression, pollination and conservation of grassland birds, were higher in perennial grasslands.”

The team also found that the grass crops’ ability to harbour such increased biodiversity is strongly linked to the fields’ location relative to other habitats. For example, pest suppression increased by an additional 30% when fields were located near other perennial grass habitats. This suggests 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, Landis said.

“The implication is that careful design of bioenergy landscapes has the potential to enhance multiple services in food and energy crops, leading to important synergies that have not yet informed the ongoing bioenergy debate,” the researchers noted.

However, 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.

“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 gases,” Landis warned.

“With supportive policies, we envision the ability to design agricultural landscapes to maximise multiple benefits.”

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