Research center tracks differences on nutrient content, placements, timing

Ray Mueller


What's the best placement spot for fertilizers applied to corn and soybeans? When should those applications occur? What are the differences in fertilizer ingredients and combinations of them?

Answers to those and related questions are being pursued on leased land, dubbed as a Research Center, along Middle Road in central Manitowoc County by Poplar Farms Sales & Service. At a recent field day, farmers, agronomists and product company representatives viewed the extensive 2016 plots and were presented with the yield results from 2015 on the various comparisons of fertilizer products and application methods.

Poplar Farms, which is owned and operated by the Bill Brunner family and their employees, is a dealer for a number of the 27 fertilizer products for field and fruit crops developed by the Michigan-based AgroLiquid company and which are used in the research plots. This year the varieties grown in the plot, planted relatively late on May 20 and 22, are Asgrow's 2.0 maturity 2031 soybeans and Dairyland Seed's 95-day 9593 hybrid grain corn.

Dairyland representatives calculate the harvest yields for the test plots. Those plots consist of 2 acres each of two plot replications of the soybeans and 2 acres each of six plots of corn.

Bill Brunner

Research site background

In setting the stage for the field day, Brunner told attendees that the purpose of the plots is to compare the results of conventional products and application practices with the new ones now available to farmers. He noted that there are two plot replications for each of the multiple comparisons.

Some special conditions apply at the leased site, Brunner acknowledged. One is a significant soil compaction pan that thwarts a 200 horsepower tractor with only four digging teeth on a deep tillage machine, he said. He intends to use commercial Gypsoil in a long-term effort to deal with the compaction.

A related challenge is the calcium to magnesium ratio in the soil, particularly a shortage of calcium because of how it was removed in crop production over many years, Brunner observed. With calcium being large pieces in the soil and magnesium being smaller pieces, a ratio imbalance toward magnesium means tight or bonded soil that limits the potential for yields, particularly with corn.

It's not unusual to have one soil, nutrient or weather condition that limits yields, Brunner said. With corn, the plants are inhibited in extending their roots in tight soils, resulting in a yield stall that falls short of the genetic potential of the corn hybrid.

In addition, the land was a frequent recipient of municipal sludge, Brunner said. As a result, soil tests show a healthy reserve of phosphorus that is, however, not available to corn plants because it is bound by the aluminum and other hard metals that were prominent in the sludge in the past.

Heavy rains on the day before a field day at Poplar Farms illustrated the problem with water infiltration due to a hard pan layer in the soil at the research site in Manitowoc County.  The pit dug for the occasion, from which water had been pumped previously, nonetheless showed the difference in the soil profile.

Corn plot observations

Despite what he described as “a phenomenal growing season” for corn in the area, Poplar Farms employee and plot manager Steve Kuenstler told field day attendees that the limitations which Brunner described are likely to have an overall effect on yields again this year. Nonetheless, he expects to have a number of yields topping 200 bushels per acre on several of the treatment plots.

Differences in the sizes of corn ears at the Poplar Farms research site in Manitowoc County are attributed to varying nutrient components, application methods and timing.

Even before the yields are documented, there were definite differences in the Dairyland Seed 9593 hybrid that could be observed during the growing season, Kuenstler reported. This included a 2-foot difference in corn plant height at one point depending on nitrogen application rates and dates, he pointed out. By late August and early September, it was evident that most of the plot was short of nitrogen, he added.

The fertilizer research compares products placed in-furrow, broadcast, or sidedressed, and foliar application of a nitrogen relatively late in the growing season, Kuenstler indicated. Another variation for 2016 was the use of the 360 Y-Drop unit for placement of nitrogen around corn plants.

Steve Kuenstler

Yield result and expectations

As a result of what he's already observed, Kuenstler expects some major differences in per acre corn yields in October. Similar to 2015, he expects top yields from the upfront in-furrow application of Agro-Liquid's combination of a germination stimulation liquid plus potassium, sulfur, and micro-nutrients.

That treatment promotes faster early season root growth and produces plants with thicker stalks and leaves, according to the plot report for 2015 and Kuenstler's observations for this year. That treatment, which nurtured a 215 bushel per acre yield in 2015, posted yield advantages of 6 to 15 bushels per acre over the other four fertilizer packages in the in-furrow comparison.

For the five broadcast surface applied pre-emergence fertilizer combinations in 2015, there were per-acre yield differences of up to 25 bushels with 216 bushels being the top yield. Showing the value of timing, there was a 24-bushel advantage in 2015 to a nitrogen application at tasseling compared to an earlier side-dress banding placement.

When side-dress applied to corn at its V6/V7 growth stage, a comparison of six nitrogen products at liquid rates of 50 gallons per acre plus some supplements did not lead to great yield differences in 2015. The yields ranged from 201 to 211 bushels per acre.

Research insights

Agro-Liquid's director of research Jerry Wilhm, who is based at St. Johns, MI, does not subscribe to a “one and done” approach on fertilizer for growing corn. With a goal of applying what's needed at the appropriate time, he likes split applications of nitrogen and potassium as dictated by monitoring during the growing season.

Wilhm also commented on phosphorus, particularly in relation to its application in dry or liquid form. He acknowledged “catching flack” for his observations that dry phosphorus has the potential of leaching into runoff water (both tile and surface), particularly in no-till settings, and thereby polluting surface waters.

One way to address this problem is to encapsulate phosphorus in a carbon cover for a more controlled release period, Wilhm stated. Although it costs more per unit, he prefers band applying phosphorus in a liquid form, thereby preventing runoff and reducing the overall per acre cost compared to the broadcast application of phosphorus in a dry form.

Based on his research career of more than 20 years, Wilhm is also convinced of the importance of giving attention to micro-nutrients such as manganese, sulfur and boron — all of which are included in one or more of the company's micro-nutrient formulated products. Regarding boron, he noted that a deficiency will appear as a crinkling on the edge of corn leaves.

Jerry Wilhm

Soybean observations

Unlike with the corn plots in the Poplar Farms research project, there were no evident physical signs of any significant differences in the Asgrow 2031 soybeans that would suggest yield variations in the plot, Kuenstler told the field day attendees. And because they weren't planted until May 22, the soybeans were not yet showing any yellow leaves on the September 8 field day.

Kuenstler noted that the targeted population for the replicated plots with 12 different fertilizer products or application method variations was a relatively high 170,000 plants per acre in 30-inch rows. Some white mold developed in the plot but no fungicide was applied to reduce its effect.

The application methods, with similar products and volumes, include in-furrow, undercover (machine placement under the foliage), 360 Y-Drop (late season targeted placement of nutrients) and broadcast applications before planting. Kuenstler's preharvest observation for 2016 is that the soybeans responded better to the foliar application of nutrients at the R1/R2 growth stages compared to the earlier in-furrow placement.

Yields in 2015

In the Poplar Farms plot in 2015, soybean yields ranged from 54 to 58.9 bushels per acre in a comparison of five in-furrow and foliar applications with various mixes of products. Somewhat surprisingly, the portion of the plot not treated with any of the products had a yield of 57.7 bushels.

Other observations and conclusions from the 2015 soybean plot were that the in-furrow application of the product with phosphorus did not yield a response in soil that has a high phosphorus residual, that a foliar potassium product seemed to depress yield compared to another potassium formulation and that there was no yield response to a foliar application of manganese.

The findings at the site can serve as a guide for growing crops on the heavy clay soil fields in northeast Wisconsin — an area extending from Door County to southwest of Fond du Lac, Kuenstler suggested. He noted that the results with Agro-Liquid's lineup of products are likely to differ from those obtained on the more gravelly or lighter soils at the company's research facility in Michigan.

Farmers, agronomists and other interested persons are welcome to visit the research plot at 7816 Middle Road or by arranging a tour with a call to 920-758-2961 or 800-466-9961.