Nitrogen-based fertilizers applied to corn and other crops in Wisconsin is partially to blame for unsafe levels of nitrate found in wells around the state, researchers say.

What is nitrate?

Nitrate is a compound naturally found in plants and in vegetables and can be found in groundwater, depending on how much fertilizer and manure is applied to fields.

Sauk County farmer Jim Goodman, seen here at the farmers’ market in the village of Dane, said he believes Wisconsin’s nitrate problem has been exacerbated by “too many animals in too small a space” and the government’s failure to enforce pollution laws. Goodman is an organic farmer who uses nitrogen-fixing cover crops and manure rather than artificial fertilizers.

Going organic: One farmer’s fight against contaminants in the groundwater

In the early 1990s, Jim Goodman and his wife began to worry about how the chemicals they were using on the farm might affect their children. The fourth-generation Wisconsin farmer decided to make the shift away from conventional farming at his Sauk County operation. Now certified organic, the farm includes 120 head of cattle on pasture, including 45 milk cows, and 300 acres of crops.

Land use is a factor boosting the level of nitrate in the water in Wisconsin. In the Upper Midwest, millions of acres of grassland — which leaches little nitrogen into aquifers — have been converted into fields of corn, soy and other crops since 2008, according to University of Wisconsin-Madison researchers. Here, a farmer harvests corn near Blair in Trempealeau County.

Nitrate in water widespread, current rules no match for it

Levels of nitrate, one of the Wisconsin’s top drinking water contaminants, are increasing. Nitrate comes primarily from fertilizers, including manure, and puts infants and expectant mothers particularly at risk. A projected 94,000 households are drinking private well water with unsafe levels of nitrate. And many of them don’t even know it since few private well owners conduct regular testing.

The number of CAFOs, or concentrated animal feeding operations, has shot up in the past decade — as have concerns about their impact on water quality and quantity.

Big farms, frac sand mines could feel force of judge’s groundwater ruling

Two weeks ago, Administrative Law Judge Jeffrey Boldt approved the state Department of Natural Resources’ issuance of permits for a large and controversial dairy farm in Central Wisconsin. But he also reduced the amount of water the farm could pump from proposed high-capacity wells and required the DNR to consider the impact of the withdrawals in conjunction with other, nearby wells — a concept known as cumulative impacts.