By Elizabeth Dunbar

MPR.org/90.1 FM

As rains have gotten heavier, Minnesota farmers in recent years have been expanding a 150-year-old drainage system, pulling billions of gallons more water off soggy land and letting the state’s corn and soybean fields thrive.

They have laid thousands of additional miles of water-absorbing plastic tubes underneath their fields and, as a result, they have pushed upward the number of bushels per acre of the crops that dominate Minnesota’s agricultural landscape. They have held their own and even flourished amid the rains, increased temperatures and greater variability observed in the state.

If only adapting to climate change were so simple.

In reality, farmers’ decisions about how best to adapt have broad implications not only for their own livelihoods, but also for Minnesota’s economy and the state’s most important natural resource: water. More intense drainage practices are a case in point, because while the popular approach makes crops and soil more resilient in a changed climate, all that extra water draining from fields can cause problems downstream.

The tradeoffs are both environmental and economic. Should a farmer change to a more resilient seed variety or different crop, or stick with what’s done well in the past? Should a livestock producer invest in new cooling systems to anticipate longer and more intense heat waves, or just cope when it happens, perhaps by sending animals to market early?

“A lot of farmers are sitting there thinking, ‘How do I manage my risk? How do I hedge my bets?’ And it’s a really complex equation,” said Joshua Stamper, an irrigation specialist with the University of Minnesota Extension who helps farmers calculate whether it makes sense to add irrigation systems to deal with the frequent micro droughts that have been observed in recent years.

“There’s no right answer. Every situation for every farmer is different,” he said.

Responding to heavy rains

Rising temperatures have had some impact on livestock and crop producers. Heat puts stress on animals, and warmer temperatures translate into a longer growing season that can change which parts of the state are optimal for certain crops. Some farmers are experimenting with different crop rotations as a response, and some livestock producers are looking at cooler concrete floors for pigs or geothermal cooling systems for barns. But changing rainfall patterns are proving to be the bigger climate challenge to farming in the state.

Minnesota is wetter than it used to be, and the amount of precipitation falling as heavy storms is up by 37 percent in the past 50 years. Scientists have tied the increases to warming global temperatures.

“I don’t think it’s hard to argue that we’re seeing heavier rain events,” said Bruce Peterson, who grows corn near Northfield and is president of the Minnesota Corn Growers Association. “It seems like we’re getting those 25-year storm events every few years, but at the same time following up that storm event it may not rain for several weeks.”

Wet fields make it tough to plant and can stunt a plant’s growth, and big storms can carry valuable topsoil away.

So since the 1800s, Minnesota farmers have been installing drainage systems to make wet fields more productive. About a quarter of Minnesota’s agricultural lands are tiled, and the wetter springs observed in the Midwest in recent years have driven farmers to add even more, said Jerry Hatfield, director of the U.S. Department of Agriculture’s Midwest Climate Hub.

“It’s a very important thing for us to realize that we suffer from too much water in the spring, and we suffer from too little water in the summer,” Hatfield said. “We really have the crop at a distinct disadvantage.”

Some farmers are dealing with it better than others, Hatfield said. For example, some have tried to work on fields that are too wet, which flattens the soil and can cause tractors to get stuck, he said.

In most cases, the excess water drained from a field flows through ditches and empties into streams. That’s a lot of water going from field to stream more quickly than it used to.

“You ultimately have an altered hydrologic system, so you have a much flashier runoff into the rivers and streams, which increases erosion of bluffs, banks, cutting in the stream,” said Gaylen Reetz, who oversees watershed management for the Minnesota Pollution Control Agency.

For example, flows on the Minnesota River have increased, and erosion has been a major problem.

“You’ve taken this enormously flat area, much of which was disconnected from the river system, and you’ve drained it,” said Peter Wilcock, a professor in watershed science at Utah State University who studies the Minnesota River. “The best evidence available right now is that drainage is playing an important role, particularly in the spring.”

Wilcock is leading a stakeholder group whose goal is to figure out where and how to retain more water up in the watershed.