ISA adds sulfur, insecticide on-farm trials

DECATUR, Ill. — Two new field trials will be added to the On-Farm Trial Network in 2025 and the Illinois Soybean Association is seeking farmer partners to participate.

ISA is coordinating research to evaluate the yield impact of soybean sulfur fertilization across different environments in the state.

Another trial partners with Nick Seiter, University of Illinois Extension field crops entomologist, on a study examining the return on investment from insecticide seed treatments and foliar insecticide applications. Cooperators will compare their preferred insect control methods with untreated control plots.

“For the sulfur trials, we will look at what the impact of sulfur is on soybean yield,” Stacy Zuber, ISA research data scientist, said at the recent 4R Field Talk at the Farm Progress Show site.

“Does adding enough sulfur help soybean yields? Is that an important thing that farmers need to add to their nutrient management by applying sulfur each year, or is it not giving enough of an ROI and not worth applying.

“We’re trying to get between 12 and 16 farmers around the state to do that trial with us.”

ISA has a goal of four sites for the on-farm insecticide application trials.

“The trial looks at the return on investment for insecticides in soybeans as a seed treatment or foliar-applied, the impact on yield. Dr. Seiter is also going to have some of his graduate students help to look at plant injury assessments in the field,” Zuber noted.

“ROI will be a big part of the insecticide trials because the economics is not just did it affect the yield but also have we hit some kind of economic threshold with the injuries.”

ISA’s agronomy team will assist farmers develop the layout of the on-farm strip trials in the field.

“Primarily for the most part, particularly in the sulfur trial, once the sulfur is applied, there’s nothing different that a farmer would have to do. They’ll harvest it like usual. We need to make sure the farmers have calibrated yield monitors. We will collect the yield monitor data and we can use that to identify what the impact was the sulfur on yield,” Zuber said.

“The hard part with that trial is just making sure that we get the sulfur applied. Most of that will be pre-plant or at planting as a starter. We can be really flexible how a farmer wants to apply that. After that, it’s just the yield data.

“We will be there as it gets started and we hope to have people on the ground to help the farmer if they need it and making sure we’re setting this up properly, that we’re getting the strips that we designed, having a prescription for them for how they’re doing it in the field.”

The ISA agronomy team conferred with U of I soil fertility professors who found the sulfur removal rate for soybeans is about 15 to 20 pounds per acre.

“For the sulfur trials right now, we’re just sticking with a relatively simple question of does sulfur impact yields or not. We plan to apply 30 pounds of sulfur,” she said.

“We want to make sure we’re well above 15 to 20 pounds to see in general if sulfur is making an impact. In future years, we may continue these trials where we’re dialing is to see if the source of the sulfur makes a difference and is there a better rate for the ROI.”

Trio of Trials

ISA deploys and manages three categories of trials — legacy trials, action trials and demonstration trials.

Legacy trials are long-term strip trials to evaluate the impact of cover crops and tillage on soil health. ISA hopes to expand these trials to more sites around the state.

“The legacy trials are long-term five-year commitment for farmers to compare cover crops and not covers in replicated strip trials across the field. That will be a continuous thing, so every year we hope to add a few more of those and cover little more of the state and get some really good data on how the soil health changes and how it is effected over time and looking at that in different soils,” Zuber added.

Action trials are flexible, replicated trials addressing relevant agronomics on topics ranging from pest management to planting rates. They report findings and actionable guidance as soon as possible.

“Going forward in 2025, we’re excited about our action trials which are going to be the type of trials with a quicker turnaround or short-term trials. We’re doing it on-farm, so we’re recruiting farmers to participate in this. We will do replicated strip trials on their farms to evaluate different types of agronomic management decisions,” she said.

“Demonstration trials are less intensive and provide qualitative insights that provide an opportunity to highlight new products or practices.”

Sign Up

ISA’s Field Advisor website has a link to the On-Farm Trial Network to sign up for a trial.

“We will be putting out a press release after harvest for a push to recruit farmers. That will be late October into November. They can also reach out to me in email,” Zuber said.

“We really want to make sure we’re covering the whole state, particularly on the sulfur trials, to see where it does or doesn’t have an impact on certain soils. We’re looking for 12 to 16 farmers across the state.

“Because the insecticide trials has an injury assessment that Nick Seiter’s students will be doing, it will probably have to be close geographically with only four sites.”