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Sept. 9, 2015

Grant to help increase biofuel yield while limiting fertilizer use

Michigan State University has earned a $5 million grant from the U.S. Department of Energy to better understand how biofuel crops acquire nitrogen, insights that could help maximize yields while minimizing fertilizer use.

Sarah Evans, an integrative biologist at MSU’s Kellogg Biological Station, and a team of MSU colleagues will study how plants interact with microbes living near their roots to obtain nutrients, especially biofuel crops growing in abandoned farmlands, or marginal lands.

Dumping nitrogen fertilizer on marginal lands doesn’t make financial sense and, environmentally speaking, can result in more nitrogen washing into waterways. Perennial bioenergy cropping systems such as switchgrass and miscanthus, however, have the potential to increase nitrogen retention in marginal lands while producing bioenergy that’s not in direct competition with food production, Evans said.

“Nitrogen is the most commonly limiting nutrient for plants, which is why fertilizer is often added to cropping systems” she said. “Nitrogen is especially low in marginal lands, which makes it an interesting system. What strategies do plants use to acquire nitrogen? How do plants respond to fertilizer application? We think their interactions with microbes are central to these questions, and will help inform how to manage these lands in the future.”

The team will conduct the study at six sites in Michigan and Wisconsin. Along with growing plots of switchgrass and miscanthus, both fertilized and unfertilized, the scientists also will study a blend of five species of native grasses and a mix of 18 species of prairie plants. The idea is to test whether biofuels grow better in a mixed-plant setting or on their own, and whether these lands could be used to provide other ecosystem services, like increased biodiversity or habitat restoration.

In these different systems, the team will focus on how biofuel crops interact with microbes to obtain nitrogen. Recent studies suggest that switchgrass barters with soil bacteria and fungi to obtain its nitrogen. Through their roots, plants give microbes carbon they need and microbes fix nitrogen, taking it from the atmosphere and giving it to plants, Evans added.

“If the plants get nitrogen through fixation, they’re giving up carbon – it’s an investment,” she said. “And it’s an expensive one. In the end, we don’t know when the investment pays off, and when plants get nitrogen in other ways. But the give and take between microbes and plants is what ultimately determines both the plant’s health and the soil’s health.

Additional MSU researchers contributing to the study include: Lisa Tiemann, soil biology; Maren Friesen, plant biology; and James Cole, microbial ecology.

“There’s a new movement in science, delving into the critical roles that microbes play in everything from human health to how plants survive and thrive,” Evans said. “We’ve pulled together a talented and diverse team to explore the many facets of plant-microbe interactions, which is needed to understand how we will use marginal lands for bioenergy while minimizing any harmful effects to biodiversity, soil health or drinking water.”

By: Layne Cameron

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