Opinion editor’s note: Star Tribune Opinion publishes a mix of national and local commentaries online and in print each day. To contribute, click here.
•••
I’m a farmer in southeastern Minnesota, the specific area of highest concern for nitrates in our groundwater (“Proposed fertilizer tax could aid nitrate cleanup,” March 2). Much of this region is underlaid with “karst geology” — fractured limestone very close to the surface, often with large cracks and crevices, including caves, running deep underground and directly to the aquifers that many wells draw their water from.
Some of the area, like on my farm, is overburdened with very deep, high percentage of clays — “glacial till.” There’s 120 feet of this over the bedrock on my farm. But only a few miles away, the limestone outcroppings are often visible along the valleys.
Water moves both vertically and horizontally, using gravity to take the path of least resistance. Just because I have very deep, tight soil on my farm doesn’t mean that nitrates from my land can’t or don’t end up migrating laterally across the landscape until the water reaches an easy pathway down through the fractured limestone. My heavy soils slow this process significantly, but eventually, the water will recharge the aquifers. If it didn’t, the aquifers from which we draw our well water would simply dry up.
Tight soils like clays don’t drain well, so most farmers put drain tile in to get them to drain faster, so the ground can be worked and a crop grown. The excess goes into our surface waters and, you guessed it, takes soil nutrients with it, unless they’ve been captured before that water left the field.
We are all responsible for this situation. When considered as an aggregate per acre, those who live in residential subdivisions often may be applying more nitrogen and other chemicals per acre than a corn farmer does — literally just to have the greenest lawn in the neighborhood. The $176 billion lawn care industry in the U.S. bears testament to this fact.
Each farmer, individually, must make these decisions for a lot more acres. Agriculture as a whole, in the Midwest, is the primary “land use” on a percentage of acres in any given area. And therefore, agriculture affects more gallons of water in any given watershed (unless you’re in northern Minnesota, where forestland dominates).