Northern Michigan University found a way to repurpose the wood ash from its biomass facility instead of paying a tipping fee to dispose of it in a landfill. Because wood ash is high in pH, it can act as a liming agent and neutralize the acidity of soil. Upper Peninsula farmers typically purchase lime to improve soil conditions and increase their crop yield. So in a mutually beneficial arrangement, the university is transporting the wood ash directly to an area farmer who has the equipment and permit required to apply it on his field, as well as a proper unloading and storage location. It saves both parties money and extends the sustainability chain. The byproduct of burning a renewable resource to supply campus heat and power helps to enrich the soil that nurtures locally grown crops.

“We have a liming license with the Michigan Department of Agriculture and we’ve had the wood ash tested to ensure it’s safe for agricultural purposes,” said Gisele Duehring, associate director of facilities at NMU. “We renew that license every year and get updated testing. Wood ash in itself is not a fertilizer; it complements nitrogen and helps crops absorb nutrients from the soil. They couldn’t use it as cover material at the landfill, which would have resulted in a lower fee, so it would have to be disposed of there. I’m just tickled it can be put to more productive use. There may be ways to explore using it for sandy areas at the NMU Golf Course as well.”

Curt Goodman, Marquette water/wastewater superintendent, attended a pre-planning workshop for the biomass facility. He oversees the city’s biosolids program, which recycles organic material derived from wastewater treatment to improve soil quality. Determined that NMU’s green project should not involve disposing of a usable product, he offered to facilitate the connection between NMU and agriculture.

“It’s a goal to utilize any byproduct for sustainability and always look outside the box for ways to reduce costs,” said Goodman. “I asked NMU to haul the first load of 16 cubic yards of ash to the storage facility at the [wastewater] plant because I wanted to see it and assess the challenges for application. The farmer came to look at it and said he had the right equipment, so I helped him with the permit process and in deciding how much to broadcast on his field.”

NMU student Eric Martin became involved on the advice of his Freshman Fellow adviser Suzy Ziegler, head of the earth, environmental and geographical sciences department. He helped Duehring apply for the liming license and assisted Goodman in preliminary research on alternative uses for wood ash and biosolids.

“That really interested me,” Martin said. “I toured the Ripley Heating Plant and the wastewater treatment plant. Curt and I brainstormed how an experiment could be set up to combine biosolids and wood ash and test the effects on soil remediation.”

The goal was to create test plots on an area behind the wastewater plant and compare the growth of crops in soil amended with wood ash, biosolids and various combinations of the two to determine the ideal ratio for optimum soil. They weren’t able to complete the research, but Martin said he might tackle it as a senior project. He did present a poster last spring on beneficial uses of leftover ash in agriculture and mine reclamation.