Wisconsin's Green Bay sees dead zones, too

Academic: Excess manure from farmland is culprit

 

CASCO, Wis. — Village Kitchen owner Chris Jacobs got a call no restaurant owner wants to take: Elevated nitrate levels in her water made it unsafe for customers to drink, the Wisconsin Department of Natural Resources said in April.

The state agency “just told me I had to put signs up saying there were high nitrates in the water,” Jacobs said. “People were bothered by it.”

With nitrate levels rising as high as 24 milligrams per liter — more than double the safe limit — Jacobs paid $11,000 to dig a new well serving the Village Kitchen.

The Green Bay watershed, which makes up roughly a third of Wisconsin’s total acreage, is facing the same water quality issues as the Mississippi River basin, where nitrate and phosphorus from industry and agriculture have created a dead zone in the Gulf of Mexico.

Green Bay, too, has summer dead zones, and one researcher says they are getting worse.

“That’s the same process that’s occurring in the Gulf of Mexico,” said Val Klump, dean of the University of Wisconsin-Milwaukee’s School of Freshwater Sciences. “It’s the reoxidation of that organic matter that consumes the oxygen.”

 

Klump, who has mapped hypoxia in the bay since 2009, published an article in October’s edition of the Journal of Great Lakes Research showing hypoxia has worsened significantly in the past decade. Agriculture has been one of the main contributors.

“The major issue for Green Bay is how much nutrients and particularly phosphorus is coming off the landscape,” Klump said. “The effort by the DNR and others is to take steps to at least attenuate how much is coming off landscapes.”

Kevin Fermanich, a professor at the University of Wisconsin-Green Bay and an expert in sustainable agriculture, said excess manure from dairy farms has been the primary culprit.

“The piece of the story that I still don’t think is fully addressed is just the amount of phosphorus, which is mostly related to manure in our area,” Fermanich said.

Farmers apply the manure as fertilizer to corn and soybean fields. But Fermanich said there is more manure on fields than what is even optimal for agricultural productivity. Persuading farmers to reduce applications and waiting for crops to take up those excess nutrients is not an overnight process.

“It’s going to take a long time,” Fermanich said. “Tens of years.”

The Lower Fox River Demonstration Farms, a collaboration between producers, crop consultants and conservation officials, has worked on educating farmers and others about changes in nutrient management and tillage and use of cover crops, but these measures have not had much of an impact yet, Fermanich said.

“There is definitely more cover crops than we’ve ever had before, and there’s more movement to less tillage than we’ve ever had before,” Fermanich said. “Whether it’s significant with the standpoint of having an impact yet on the cumulative impact of the river and the bay, I don’t think that has happened.”

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