The soil and water near some of the most polluted wells in Minnesota is almost entirely clean three years after a new type of wheat was planted on the surface.
The perennial wheat, called Kernza, was grown just west of Brainerd on a few acres immediately surrounding wells within corn and soybean fields. Over the past three years, it cut nitrate contamination from the cornfields by 96% and from soybeans by 86%.
The drastic drop of the increasingly prevalent and damaging nitrate pollution shows that even small plantings of the wheat crop may be able to protect water supplies throughout central and western Minnesota, potentially saving taxpayers and small towns from spending millions of dollars on nitrate treatment systems. That all depends, however, on how quickly the demand and market for Kernza can grow, and if the wheat will be profitable enough to make it worthwhile for farmers to carve out space to grow it inside more established corn and soybean operations that dominate Minnesota's landscape.
"We're seeing some promising results from a relatively small amount of acreage," said Jacob Jungers, a researcher at the University of Minnesota. "We have cities that are becoming somewhat desperate now for a solution. The idea is to keep expanding the size of the project, increasing the acreage to the point where we can start to see the direct impact on a community's drinking water."
The U has been running similar experiments in small areas around wells throughout the state. Each time Kernza is planted around a well, the nitrates in the soil and water under the crop fall to a fraction of previous levels.
Planting above wells
The goal isn't to replace corn or soybeans, but to rotate in Kernza for a few years or to plant the wheat on targeted areas directly above wells. The wheat would potentially become a profitable buffer, Jungers said, preventing fertilizers from leaching into water supplies while keeping the land in production.
Over the last 30 years, nitrate levels throughout much of the state have been steadily increasing. Farm fields aren't the only source of nitrates, but as farming has become more dominated by intensive corn and soybean cultivation, vast areas have lost much of the alfalfa, barley and other cover crops that used to keep soil healthy and defend against erosion during the wettest months of the year.
More than 50 communities have watched nitrate levels reach or exceed federal safety guidelines, according to the Minnesota Department of Health. Many of those cities, including Hastings, St. Peter and Edgerton, have had to build expensive water-treatment systems, costing the households they serve thousands of dollars.
Rising nitrate levels
Nitrate levels throughout Stearns County have been trending up for more than a decade, said Dennis Fuchs, administrator of the Stearns County Soil and Water District.
The central Minnesota county has been working with the U to grow Kernza in trial areas around some of its more polluted wells for the past three years. The results have been promising, and the county has asked lawmakers to continue funding the study for another three years.
"If we can target these sensitive wellhead areas, hopefully we will not have to put in nitrate treatment systems and [we can] save a tremendous amount of dollars," he said.
The environmental benefits of a perennial crop are all about the roots, Fuchs said.
Kernza, which was developed in Kansas after decades of breeding, has roots that grow twice as long as the common annual wheats grown throughout the United States, and many times longer and thicker than the roots of corn and soybeans found on most of Minnesota's farmland. Unlike annual crops, the Kernza roots stay in the ground year-round, preventing erosion and runoff by holding soil together.
The Kernza plant is at its hungriest in the early spring, soaking up nutrients from fertilizers at the exact time nearly barren corn and soybean fields leave the earth vulnerable to nitrate leaching and erosion.
Kernza has only been around for a few years. Many of the Minnesota farmers who have been early to try it are expecting their first yields in the fall.
The early signs of the crop's benefits come just as the state tries to encourage cover cropping to get more roots in the ground for longer periods of time.
Only about 2 to 5% of farmland in Minnesota has cover crops, said John Jaschke, executive director of the state Board of Water & Soil Resources. The board is trying to get $5.5 million in additional funding to help farmers add a host of different cover crops and reduce tilling.
At a news conference Tuesday, Jaschke said farmers need the technical assistance and direct payments to help make the changes.
"The total amount of land that is in these practices has still got quite a way to go," he said.
Staff writer Jennifer Bjorhus contributed to this report.
Greg Stanley • 612-673-4882