Unwrapping The Soil

Big yields begin with site selection on this Nebraska farm.

Wiles Brothers agronomist John McNamara rates site selection, hybrid choice and early stand establishment as the top factors in harvesting high yields, Image by Bob Elbert

The corn yield on the Wiles Brothers Inc. Missouri River bottomland farm, near Plattsmouth, Nebraska, has been growing every year since the drought of 2012. In 2014, the brothers placed first nationally in the National Corn Growers Association’s National Corn Yield Contest No-Till/Strip-Till nonirrigated class. In 2017, they took second place nationally in the class with 351.2551 bushels per acre. That was produced by way of a DeKalb DKC64-35RIB entry.

As the farm’s agronomist for 10 years, John McNamara says site selection, hybrid brand and number choices, along with stand establishment, are the top three factors responsible for the operation’s high overall corn yields and for heavy yield-contest entries each year by owners Glenn and Marvin Wiles.

The third-generation farm, which also operates an ag retail business (seed, chemicals, fertilizer and custom application), is a 50/50 corn and soybean rotation with annual corn yields ranging above 200 bushels per acre and per-acre soybean production averaging above 60 bushels. The entire farm is regularly soil-sampled on 2.5-acre grids.

“Site consideration is very important, whether you are planning to enter yield contests or are selecting hybrids and management practices for commercial farming,” McNamara explains. “Our approach is to look at overall fertility and water-holding capacity of the soils in question, and consult our history of records to formulate a base for my fertility and genetic plan for a given field, plot or grid.”

WINTER PLANS. The agronomist says his crop-year planning begins after Christmas, and once site parameters are known, he begins consulting charts of hybrids and their performance to select the seed for specific sites. For the farm’s contest plots, McNamara says he compiles soil organic matter levels, pH and phosphorus and potassium levels, then works with his DeKalb agronomists to determine the best hybrids for the sites being considered.

“Folks in the seed business are very good at matching soil and site conditions to their seed portfolio. They’ve been looking at hybrids for eight to 10 years under varying conditions, and they can help suggest three to four hybrids for each of three to four sites to hedge performance bets under expected weather conditions,” he says.

McNamara is sold on having fertility in the root zone at variable depths early.

“Fertility and field preparation begins in the fall, right after harvest,” he explains. “We want an even spread of soybean residue to allow us to achieve even stand establishment next spring and that picket-fence stand of corn that is needed to achieve high yields. It’s at that time, too, we’ll be soil-sampling the fields with potential yield goals in mind.

“If our target is 350-bushel corn, and there is a given amount of nutrients credited to the previous crop, we’ll address those fertility needs in the fall and hope for early spring rains or snows to incorporate it throughout the root zone.

“I’m not a fan of foliar feeding because there’s always a lag between application and plant response,” he continues. “I want to make sure the nutrients are plant available in the soil solution prior to when the crop needs them.”

REAL DIRT. McNamara favors actual soil probes to measure fertility rather than relying on digital measurements. “There are just too many variations of chlorophyll color between hybrids, and I’m never convinced NDVI [normalized difference vegetation index] readings can be as accurate as a site-specific soil sample,” he explains. He’d rather put a probe in the ground and know exactly what the roots are dealing with in the soil profile. “Whether you’re managing a commercial farm or coaxing yield contest plots--or both--the stakes are high, and you need to be out there in the field.”

Wiles Brothers use several commercial dry spreaders to apply on-farm-developed fertilizer prescriptions by variable-rate technology (VRT) on 2.5-acre grids. In-furrow fertilizer and starter solutions flow according to variable-rate cues from the farm’s John Deere rate controllers and 1795 ExactEmerge planters.

The agronomist says Bayer’s Acceleron is a standard treatment with fungicides in his liquid starter solutions. He opts for the liquid rather than “banging seed around in a drum” with conventional seed-treatment-preparation methods.

SMALL WINDOW. “After that, it’s timing and prayers,” he explains. “I like to see kernels showing life, breaking ground seven to 10 days after planting; and, to do that, one needs to orchestrate planting around soil moisture, rain possibilities and ground temperatures.

“It’s a fairly small window to get planting right. You can’t go back after you fold up and pull out of the field,” he says.

McNamara shoots for total stand emergence within hours of the first plant to emerge and says losing one or two plants per thousand can make critical differences in yield. Currently, planting rates range up to 44,000 plants per acre.

“You have to have the plants to manage them,” he explains. “Once they’re up, anything I can use to help them I consider. The first thing we usually do is apply liquid N (according to soil test) at V6 side-dressed with a rolling coulter. Later, a dry application around V14 to 15 follows, timed around expected rains.”

McNamara also says the use of fungicides is imperative when striving for maximum yields.

“We’ll typically run two or three postemergence fungicide applications to keep the top third of the leaf canopy clean to get as much glucose and starch production into the kernels as we can, and to maintain stalk credibility,” he explains.

Harvest, too, is an orchestrated practice for Wiles Brothers Farms. “We like to harvest at 25% moisture to minimize handling losses,” McNamara explains. “We have entertained brushes on the gathering chains on our eight-row S770 combines across the farm to minimize butt shelling and improve overall yield.”


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