MPR file photo Tom Robertson
Farmers are switching to alternative crops in an effort to protect drinking water wells for the city of Park Rapids.
The city water supply is threatened by high nitrate levels. The nitrates are a result of irrigated potatoes grown in the area. The irrigated potatoes need lots of nitrogen fertilizer. Some of the nitrogen finds its way into the groundwater raising the nitrate level in the drinking water as my colleague Tom Robertson reported.
Trying to reduce nitrogen use on the usual row crow crops hasn’t solved the problem. So this year, in about a 1.5-square-mile area, farmers are trying a new crop rotation.
The typical three-year crop rotation is potatoes, corn and beans. Those are all row crops which tend to allow more nutrients to leach through the soil to the groundwater, Minnesota Department of Agriculture Water Quality Advisor Luke Stuewe says.
In an unprecedented change in agricultural crop rotations, farmers will plant potatoes in year one and then two years of sorghum sudan grass. The grass has a thick root system that will use most of the nutrients in the soil.
That will mean an economic hit for the farmer, in this case R.D. Offutt farms. Senior Agronomist Dale Stevens says not growing potatoes will mean a loss of several hundred dollars per acre.
Stevens says there’s a long-term commitment to the changed crop rotation. But it might take a few years to see if it offers a solution to nitrate pollution of groundwater.
Stuewe says there’s a lag time between what happens with land use and the impact on groundwater.
The state will be monitoring the project closely and perhaps what’s learned will be useful in other parts of the state where agriculture threatens sensitive groundwater areas.