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Variable-Rate Technology Turns Marginal Land Into a Moneymaking Investment

Minnesota farmer transforms marginally producing land.

When a 160-acre parcel of farmland in southern Minnesota came up for sale, many wrote the irregular-shape field off as not worthy of a second glance.  

“Most farmers said they didn’t want to deal with it because there would be too much waste, and they would just be throwing money away,” recalls Cory Sumerfelt, who farms with his father, Tom, and his brother, J.J., near Cottonwood, Minnesota.

The field’s misshaped contour wasn’t the only thing that turned off potential buyers. How to effectively manage its highly variable soils, with its pockets of glacial outwash, was also a concern. 

“In this area, soils are all over the board,” says Cory, a third-generation farmer. “That 160-acre field has it all – from beach sand that nobody wants to touch to beautiful loam soil that everybody wishes they had 1,000 acres of. It would definitely be a challenge to manage.”

Blame it on the glaciers

The soils of Minnesota are a complex mosaic created by glaciers that covered the state between 10,000 and 20,000 years ago. 

“Glacial outwash materials, a common parent material in Minnesota’s soil, were deposited when meltwater streams flowed from melting glaciers at the end of the last Ice Age,” says Nic Jelinski, University of Minnesota. “These meltwater streams deposited coarse sands and gravel across many parts of our landscape. Soils subsequently formed in these materials over about the last 13,000 years through biology and climate on the parent material.”

The soils created in glacial outwash tend to be very sandy. “Therefore, they do not hold water or nutrients very well and tend to be droughty and nutrient-poor soils. Irrigation, of course, can alleviate the moisture problem, but it does not help build up the soil and retain nutrients,” says Jelinski.

“The number one battle farmers fight in this part of the state is how to manage a sand vein or a gravel pocket,” says Paul Bruns, who owns Precision Consulting Services in Canby, Minnesota. 

It’s also why naysayers said the 160 acres up for sale would never produce more than 100 bushels, on average, of corn. That didn’t deter Sumerfelt. He saw the property as an opportunity and purchased it in February 2008 for $1,060 per acre.

“With a low initial investment, I saw it as a chance to take a piece of ground I was familiar with and no one else was very interested in purchasing, and turn it around so it produces the way it is supposed to,” he says. 

Defining the issues

Aware the ground had been ridge-tilled for more than 30 years, one of the first changes Sumerfelt made was to convert to his family’s tillage practice. 

“We do a conventional-tillage program, especially if we plant a lot of corn-on-corn,” he says. “We use a moldboard plow, which most people think is terrible, but on residue management, it works well for us.”

Sumerfelt is not completely turning the soil over and burying the trash. Rather, he’s managing it in a way that doesn’t create a problem for the crop the following year.

“When I put a plow to that field the first year, it was so tight, it couldn’t breathe,” he says. “Opening up that ground gave it a much-
needed breathe.”

Tillage was only part of the equation. Collecting yield data from the very beginning provided clues that would lead to further modifications. 

“When I hit a sand spot, the yield monitor would go to zero. On the better soil, the yield would be pushing 200 bushels per acre,” recalls Sumerfelt. “It was a big red flag because I knew those sandy spots could do better with some adjustments.” 

Before he could manage inputs differently to match soil variability, he needed to know exactly what he was dealing with. Bruns recommended using Veris technology to pinpoint the variations in the soil. 

“Figuring out how to map and document what you’re dealing with to make a management decision is a struggle for many. It’s also an important step in the precision ag process. Otherwise, it’s just a guess,” Bruns says.

“When you look at a black piece of farm ground without a crop on it, you really don’t think it looks too bad. Yes, there are sandy hills here and there,” says Sumerfelt. “When I saw the soil map, those sandy hills were a lot bigger than I believed they were. It was really impressive to see.”

Now that they knew exactly what they were dealing with, Sumerfelt and Bruns began to devise a plan to turn the marginal ground around. Variable-rate technology would be at the center of the transformation.

“I was throwing money down the drain because certain spots weren’t producing for the fertilizer blend I was applying at a flat rate,” says Sumerfelt. “The spots that were yielding, I figured I was starving a little.”

Using multiple years of yield data and Veris data, Bruns created a variable yield-potential map. “This became the basis for building out variable-rate fertilizer prescriptions,” he says.

To measure fertility, 2-acre grids were set up. “It was clear I was putting P&K on an area that didn’t need it because it was only producing zero to 75 bushels. The only thing it really needed was nitrogen,” says Sumerfelt. “I reallocated the money I was spending on that sandy area from $200 to $100 an acre.” 

Those dollars were shifted to the better-producing areas. “In the first year, we shaved about $3,000 off of his fertilizer bill and saw a yield response right away,” recalls Bruns. “While there was an initial savings, it was more about putting those inputs where they could do the most good.”

Spots that had been yielding zero were now producing 140 bushels.

Seed savings

Fine-tuning the way Sumerfelt applied seed, Bruns felt, also had to be part of the plan.

“In my experience, if we are adjusting fertilizer recommendations from 100 to 250 bushels, why would we flat-rate seed across that piece of ground? Fertilizer and seed, to me, go hand in hand,” he says.

Knowing they eventually wanted to use variable-rate seeding, the Sumerfelts traded their Kinze 3600 planter in for a Kinze 3660 equipped with the technology needed. (See the story on page 48 for details.)

On average, Sumerfelt was flat-rating at 32,000 seeds per acre. By varying his seed, rates can range from 18,000 to 36,000 in the same round of a field.

When a prescription map was created, Bruns used the maximum number of rates allowable by the controller on a 10×10-foot basis so that the jump in rates is not drastic and won’t cause the controller to struggle to hit rate, he explains. 

“It also allows us to accurately apply in the transition areas that only need a slight adjustment,” continues Bruns. “Zones did a great job of helping lay out variable-rate seeding. We could pick up those yield variations really well. In the end, we’re probably saving 10% to 15% on seed in this field.”

Every year, check blocks are placed in the field to continually test the ground’s potential. “We may put a 2- to 4-acre block in the field and push the population to 38,000. If there is a response in yield, we push it a little more. If we don’t see a response, we know we don’t need to go that high,” says Bruns. “Whether we get 220 or 180, we want to know why and figure out where we should go from there.” 

The tech advantage

This 160-acre field is the poster child for making variable-rate technology pay, says Bruns.

“In seven years, if you can say you’ve raised your average by 70 bushels, that’s pretty awesome. We will continue to mine the data to ensure this ground is performing to its potential,” Bruns says.

“Technology has taught us how to properly manage this ground. We knocked that 100 bushels out of the ball park,” says Sumerfelt. “In 2015, it averaged 200 bushels per acre. Last year, it surpassed those yields by 10 to 15 bushels per acre.”

That was after a 25% stand loss from green snap in July.

Planter investment

In order to variable-rate seed, Minnesota farmer Cory Sumerfelt, who also farms with his father, Tom, and his brother, J.J., knew he would have to retrofit their Kinze 3600 planter with the technology necessary to make that happen. 

“We paid about $150,000 for the Kinze 3600 planter and ran it for two seasons,” recalls Sumerfelt. “In order to use variable-rate seeding, we’d have had to invest another $30,000.”

As they considered their options, the Sumerfelts compared that cost with a machine already equipped with what they needed.

Loaded with technologies for maximum versatility and functionality, the Kinze 3660 comes factory-equipped with single-row electric clutches. Since it has a single-motor hydraulic drive system, this planter would allow the Sumerfelts to adjust seeding rates or view prescription maps on-the-go. 

The bulk fill system, with its 110-bushel capacity, would also make everyone’s life easier, Sumerfelt notes.

“At around $175,000 for a Kinze 3660 planter that has the latest technology we want but also the capability to easily adapt to future plans, it was a no-brainer as to which one was the better investment,” says Sumerfelt. 

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