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Going underground in corn country

Tom Cherveny | Tribune

HANLEY FALLS, Minn. — Irrigation can make economic sense for many corn farmers in Minnesota, but it is not known if a more costly investment in subsurface irrigation can produce the yields to justify the extra cost.

Brian Velde aims to find out, thanks to an Innovation Grant from the Minnesota Corn Growers and the help of a University of Minnesota researcher.

Velde, who farms along the Yellow Medicine River about six miles south of Granite Falls, installed a subsurface, drip irrigation system on 58 acres of corn land. The soil varies greatly across the acreage, with areas of light, sandy soils and other areas with heavier, rich soils.

"A lot of variability. There wasn't a good answer for yield responses,'' Velde said. Using the latest technology, for more than a decade, he precisely adjusted fertilizer and seeding rates according to the soil types.

All the same, there were years when he would watch the corn on the sandy soil burn up and produce nothing while just 1,000 feet away he could harvest 250 bushels per acre on the heavy ground.

He started researching his irrigation options a few years ago, and then learned about a Kansas company's subsurface system.

Last year, Nutradrip installed its pressurized drip tape by plowing it into the ground. It runs in parallel lines 5 feet apart, with small drip emitters buried about 14 inches deep. It's placed so that every corn plant is within 15 inches of a drip emitter.

A 10-horsepower pump pulls water from the Yellow Medicine River, runs it through three sand filters and delivers it through a trenched, 8-inch pipe to the drip tape.

Velde operates it all from a computer. It enables him to both water and fertilize the corn. He feels the ability to fertigate may prove to be the biggest benefit of the system. It allows him to spoon-feed the corn just the amount of nitrogen needed and when it's most needed: That mainly being the month of July.

It has allowed him to reduce the amount of nitrogen that is land applied. And, the system's efficiency means there should be no nitrogen leaching into the groundwater.

This July has been a relatively dry one on the farm, which only underscores for him the value of being able to irrigate. The system allows him to control the drip rate so he is able to provide more water to the corn in the light soils as compared to the corn in the heavier soils.

There is no loss to evaporation as occurs with overhead irrigation systems, he said. He also pointed out that by virtue of not spraying the canopy and soil from above, he has no worries about disease or flushes of weeds.

There's also another benefit of this subsurface system. He is able to pump water and cool the soil when soil temperatures exceed 82 degrees and stress the corn. A series of temperature monitors spread across the field warn when temperatures are reaching stress levels.

There is a lot of data on the benefits of this technology in southern corn-growing states like Kansas and Nebraska, Velde said. But what about Minnesota, where there are fewer days of heat stress?

He has reason for optimism. July has been dry enough on his farm that absent the irrigation, he's convinced his corn on sandy soil would be a bust this year. With the irrigation, he's looking at lush rows of corn with double ears.

More than half the irrigated acres in the state of Minnesota were planted to corn in 2015, the latest year crop-specific figures are available from the state Department of Natural Resources. There were 616,100 acres reported irrigated that year, and 318,200 of those were for corn.

Test strips that run through the field will allow Velde and Dr. Jeff Strock, researcher with the University of Minnesota, to statistically quantify the corn yields on the different soil types with and without irrigation. Velde pointed out that it is not just the increased yields that can matter, but when they occur. A bigger yield during a dry year could mean the benefit of a higher per bushel price on the market, he explained.

His irrigation permit allows him to pump the equivalent of about 6 inches of water, or 9.6 million gallons of water in a season. In a drought event, the right to irrigate can be suspended.

The Corn Growers' Innovation Grant allows for three years of research at the site. Velde noted that it may take more years than that to fully know the economics of the investment.

He will be hosting a field day from 1 to 4 p.m. Aug. 22 at the farm, 2136 530th St., Wood Lake, for those interested in learning about the system.

Tom Cherveny

Tom Cherveny is a regional and outdoor reporter with the West Central Tribune in Willmar, MN.

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