Iowa Farm Family Pushing Toward Mid-300 Corn Yields Using High-Definition Mapping

Source: By Karl Wolfshohl, Progressive Farmer • Posted: Thursday, January 4, 2018

Dan Durick said the family is managing its ground to produce more corn on fewer acres. (Progressive Farmer photo by Jim Patrico)

Dan Durick said the family is managing its ground to produce more corn on fewer acres. (Progressive Farmer photo by Jim Patrico)

Precisely applying fertilizer and fine-tuning seeding rates based on soil textures get most of the credit for higher yields in Dan Durick’s book.

“We’re trying to do more with less,” said Durick, who farms with his brother, Joe, and their dad, Tim, in the rich soils near Council Bluffs, Iowa. “We’re of a mind-set to get more bushels on fewer acres versus fewer bushels per acre on more land.”

The Duricks, who planted corn and soybeans on 3,500 acres in 2017, use their National Corn Growers Association (NCGA) National Corn Yield Contest acres as proving grounds for new ways to economically improve their yields.

The three men attribute their success to planting high-quality seed at rates particular soils can support and, especially, focusing on high fertility where it can grow the most corn without nutrients being wasted.

The Duricks haven’t been entering NCGA’s yield contest very long — just eight years — but they’ve done well recently. In 2016, their contest plot, entered under Joe’s name, took first place in the AA No-Till/Strip-Till Nonirrigated class with 333.5 bushels per acre.

The previous year, the Duricks earned second place in the category with 318 bushels per acre.

“It’s kind of fun to win,” Dan said, laughing. “It’s also nice to figure out what might work on a larger scale. Of course, hybrids have come a long way, and precision farming has helped us tremendously. I think a variable fertilizer program has contributed 90% to our higher yields.”

The Duricks used to apply 180 pounds of nitrogen across the whole farm. Last year, on one farm, the total averaged 175 pounds of nitrogen, but there were places where they added 140 pounds, and places where they put on 240 pounds because heavy clay takes more.


Three years ago, agronomist Steve Killpack ( first towed his Veris MSP3 sensing tool over much of the Duricks’ acreage, including contest ground. The machine measures electrical conductivity, pH and organic matter of soils on 60-foot transects. These values create a high-definition soil map, which Killpack overlays with yield maps in software he designed to write prescriptions for seed populations and fertilizer placement.

“We take readings every 60 feet and get a high-resolution picture of these three values,” Killpack said. “They are the primary drivers of yield on nonirrigated land with various nutrient-holding abilities. We analyze the information and see how closely it correlates to the yield of individual fields. From this, we draw conclusions of what to do, such as to add more or less lime or nitrogen, or to increase or decrease seeding rates.”

The Duricks do what they need to do to maximize the plant’s potential with that data. “We take those readings and go with them,” Joe said. “You can’t get the best yields if something is out of place. We go with Steve’s recommendations and try to bring phosphorus, potash and sulfur back up to where they need to be.”

The Duricks apply 200 to 600 gallons per acre of byproduct from an ethanol plant to commercial acreage. This is their phosphate source, and it also contains a lot of sulfur.

Acreage that the Duricks plan to enter in the contest gets special treatment, for sure. Joe calls it “eliminating [everything] besides Mother Nature.” It’s why the contest plot yielded over 333 bushels per acre, and their farm average was a respectable 200 bushels.

They start with their best creek bottomland and give it extra groceries.

“This year, we applied 400 pounds of actual potash per acre and 1,000 gallons per acre of ethanol byproduct,” Dan said. “We made two passes of fungicide.”


Longer-season hybrids are the order of the day for the contest acres.

“In general, 108-day maturity is our earliest corn for southwest Iowa,” Joe said. “Everything we enter in the contest is at least 111-day, and 120-day is the longest corn we enter.

“This year, we doubled phosphorus and potash, and added extra sulfur,” he continued. “We put extra nitrogen down at the beginning (200 pounds actual N applied to bean stubble before corn was planted), then sidedress with more nitrogen at tasseling.”

The Duricks sidedressed with 100 pounds of nitrogen when the corn was 14 feet tall even though tissue analysis called for 75.

“We’re fortunate to have some ground that can mineralize a lot of nitrogen,” Dan said.

This year, the Duricks began experimenting with fungicides on part of their acreage, making one pass at V5 and another at R2.

“We applied the fungicides on our test plot and also did check strips on 300 additional acres,” Dan said. “Where we sprayed, there was less disease pressure.”


The prescriptions Killpack generates with data gathered by his Veris machine include seeding rates of 24,000 to 36,000 seeds per acre on the Duricks commercial acreage — those populations placed by John Deere variable-rate planters, guided by GreenStar technology.

Varying the seeding rate has saved 8 to 10% in seeding costs while producing better yields. On their contest plot, the Duricks planted 31,000 seeds per acre this year. “If we find (another) silver bullet, we’ll be doing it across the board,” Joe said.

Trying new methods on their contest acres every year has convinced the Duricks that precision farming has given them their best economic returns. “Our yields have trended better,” Dan said. “Between hail, drought and wind, we’ve actually seen 10-year averages on some farms go down a little, but overall we’re trending up.”