Water contamination: In Minnesota, we must reconsider which crops we plant

The news in the Jan. 14 issue of the Star Tribune that 1 in 8 Minnesotans are drinking nitrate-tainted water and that fertilizer escaping from row-crop fields is a main culprit comes on top of one of the toughest growing seasons in the state's history. U.S. farmers have experienced the wettest 12 months since at least 1895. I can't count the number of times last spring, summer and fall that I drove by Minnesota crop fields where equipment was mired up to its hubs; in some cases the construction equipment brought in to drag out the farm equipment was stuck as well.

Many of these fields are increasingly becoming what agronomists call "unstable yielders," and that has a direct connection to the latest bad news about nitrate pollution. A recent Michigan State University study — which, over eight years, examined 70 million acres in 10 Midwestern states, including Minnesota, with unprecedented granularity — found that around a quarter of our cornfields are consistently unstable yielders as a result of being too wet or otherwise unsuitable for cropping. Because these low-yielders waste nutrients — the lower the yields, the less plant material there is to use up nutrients — they account for more than 40% of the nitrogen fertilizer escaping into our water as a pollutant and into our atmosphere as a greenhouse gas. Wasted fertilizer is wasted money. The study estimates farmers lose $1 billion in fertilizer annually as a result of unstable yielders.

As climate change accelerates, the economic, agronomic and environmental price tags attached to those unstable acres will only go up. But these unstable fields also offer up some exciting opportunities to change the way we view "productive" farmland.

Obviously, one option is to pay farmers to allow some of the land that wants to be a wetland or even a prairie to be just that. But we need to produce food and rural communities need farms to survive, so there must be options for parts of the landscape that, with a tweak here and there, can once again be "stable" producers of cash crops. One tweak needed involves an attitude adjustment. In the Minnesota, that means ending our fixation on equating the worth of farmland with its ability to raise two crops: corn and soybeans.

The University of Minnesota's Forever Green Initiative has been experimenting with crops like Kernza, a perennial wheatgrass, and pennycress, an oilseed that can overwinter and grow alongside soybeans. What's important about this research is that not only is it tackling issues like stand durability and harvestability, but it's working on developing markets for these crops. Asking farmers to add a third crop to their rotation makes no sense if they have no place to sell it. And the U's experiment station in Morris is showing that Kernza not only soaks up excess nitrogen but makes good forage for rotationally grazed cattle — in fact, it appears to thrive under a system in which it's grazed in the fall and harvested for grain the following summer, thus doubling farmers' income potential and helping them deal with the twin economic-climate crises that are pounding them. By the way, rotational grazing helps spread manure in a way that the soil uses it to build biology, thus preventing it from becoming yet another source of nitrate pollution.

The Minnesota Legislature provided a little over $4 million in Forever Green funding in 2019. Many more dollars are needed to make a real impact, but this funding is an acknowledgment that focusing exclusively on corn and soybean production cannot overcome the climate change behemoth and keep our water clean.

Are crops like Kernza and pennycress magic bullets? No, but the philosophy behind this research — that we need to develop a way to insert into our annual, domesticated, largely inflexible, monocropping regimen a little wildness in the form of perenniality — is significant. Such nimbleness is key as climate change destabilizes more prime cropland and makes it not only a threat to farmers' back accounts, but everyone's water.

Brian DeVore, author of Wildly Successful Farming: Sustainability and the New Agricultural Land Ethic, is the editor of the Minnesota-based Land Stewardship Letter. On Twitter: @LSPLetter.