Dundas, Minn. – Brent Fuchs planted corn all day Saturday into the early hours of Sunday. He stayed up late again Monday, hoping to get his last 250 acres of soybeans in the ground.

He didn't quite get there and, on Tuesday, he said the day's rain may keep him from finishing until Friday.

Farmers across Minnesota are racing this week to get the last of their corn and soybeans planted after a cold, wet spring busted plans and kept some of them out of fields until after Memorial Day.

As of Sunday, 20% of the soybean crop and 8% of the corn crop in Minnesota were yet to be planted, according to the U.S. Department of Agriculture. That's way behind the average of the past five years; statistically, Minnesota farmers two weeks ago should have been where they are now.

Harvests are sure to be reduced as a result, and so will farmers' crop insurance coverage.

For Fuchs, this has been the latest planting in his 21 years as a farmer. Two weeks ago, he hadn't even started. "I don't remember a year where on Memorial Day weekend we had nothing planted," he said.

He and his neighbor Larry Salaba are helping each other by sharing the workload — one tills the fields ahead of the other, who runs a tractor pulling a planter on the freshly prepared ground.

Salaba was planting on Monday morning on a field west of Dundas while Fuchs knelt at the edge of the field, scooped a handful of dirt clods into his hand and squeezed. Blessedly, the clods broke apart.

"Two weeks ago, it would have been like a ribbon," said Fuchs, explaining how the dirt responds to being squeezed when it's still too wet. "This is not what I'd call an ideal seed bed, but it's too late to wait for the perfect field."

Farmers in other parts of the Midwest are even further behind. The corn crop in Illinois was only 73% planted on Sunday. Indiana was 67% planted and Ohio was 50% planted, according to the USDA.

This year will go down as one of the latest plantings in memory. Just over half of the corn acreage in the 18 major corn-producing states was planted after May 25, the USDA says. In a typical year, less than one-fifth is planted that late.

When planting reaches mid-May, corn and soybean yields drop a little at fall harvest time. But when planting happens after that, yields drop dramatically in the fall since plants have fewer hours to soak up the sun's energy.

Past studies show farmers can lose up to 24% of their harvest if they don't plant corn until June 4, and up to 31% if they wait five days longer, according to the University of Minnesota Extension.

Soybean planting can happen later, but a June 9 planting loses farmers roughly 24% of their harvest and a June 14 planting loses them 30%.

Deciding when, what and whether to plant has been like putting together a moving puzzle for Fuchs and farmers across the Midwest. They have been forced to change the type of seed they plant and reconsider the effects of market prices, insurance penalties and weather risk later this summer.

"We're going to need to have some things go in our favor," Fuchs said. "We could still have a decent crop."

Fuchs had to switch out his typical seed for another variety with an earlier maturity date. And in his second job selling seed for Pioneer, he's been helping farmers farther south switch to seed with earlier maturity dates.

Seed that's usually planted in west-central Minnesota has been planted in southern Minnesota, and seed typically targeted for southern Minnesota has been planted in Iowa and Illinois. Kern Iverson, a corn and soybean farmer south of Lamberton, had to switch seed when he couldn't start planting corn until June 2.

"Normally we plant 102-day to 108-day corn, but we switched to 92- to 96-day corn," Iverson said.

Iverson and his son finished planting corn over the weekend and then planted 650 acres of soybeans by Monday. On Tuesday, with 325 acres of soybeans left to plant, they were sidelined by light rain.

Fuchs, Iverson and many other Minnesota farmers considered not planting some of their fields this year, given how low the yields will be. But when the corn and soybean markets rallied in May, they decided to go for it, even though they planted so late that they'll be penalized on their corn crop insurance coverage. Each day into June that the corn is planted subtracts a percentage from coverage.

"Basically we're just rolling the dice," Iverson said. "We might get snake eyes and we might get box cars. I'm hoping for box cars."

The wet spring has also clogged shipping routes on the nation's rivers. Hundreds of barges are held up at locks on the southern Mississippi River because of high water and fast currents, keeping supplies from farmers and limiting crops sent to market.

By this time in a typical year, about 1,400 barges laden with fertilizer, cement and rock have made it to St. Paul. This year, only 90 barges have made it up the swollen river, said Molly Isnardi, vice president of Upper River Services.

Farmer cooperatives had to use trucks and rail to ship fertilizer to farmers, which makes it more expensive.

"It's systemwide, so it's really hurt the farmers in the entire Midwest region, because a lot of that fertilizer was stopped from getting to them," Isnardi said.

As for grain headed south to market, there's been none of that this spring, Isnardi said, even though some farmers would have liked to sell their grain after holding on to it through the low commodity prices that lasted into May.

adam.belz@startribune.com 612-673-4405 • Twitter: @adambelz