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Nitrate is a molecule that consists of one nitrogen atom and three oxygen atoms. Nitrates from chemical fertilizers or animal manures applied to agricultural land can contaminate waterways, including lakes and stream. Any nitrogen in excess of what is taken up by plants can oxidize as nitrate, which easily passes through the soil and contaminates both surface and groundwater.

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Photo by Frank and Molly


Location: AG 450 Farm, ISU
Featuring: Farm Operator Greg

“It’s a complicated issue,” Greg says. “I don’t like the way the media paints farmers. We’re not the bastards we’re made out to be."

“Plants need nitrogen to grow and they get that nitrogen by absorbing either nitrate or ammonium through their roots. With a corn-soybean rotation, like most Iowa farms, some of that nitrate has to come from fertilizer. Here, we’re very exact with our application and, generally speaking, the amount farmers apply has been going down each year.

Corn takes a pound of nitrogen per bushel, and on a good year we get 250 bushels per acre. About 20-30 pounds of nitrate comes from decaying plant matter. The remaining amount is mostly covered by the 4000 lbs of liquid manure once the ground is steadily below 50°F, with extra ammonia added in the spring.

We don’t want to spend any more on fertilizer than we have to. We know the timing and movement in the soil profile affects leaching more than the amount of nitrate put on the fields. As a result we’re considerate of things like when waves of rain are coming in because nitrate is water soluble; where the water goes so too does nitrate. We keep three feet of ground between where we inject the manure and where our tile line is. Overall, as technology becomes available it will get utilized. We’ll get better.”

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