Research evaluating yields in conservation systems

URBANA, Ill. — In response to recent dust storms in central Illinois and across the Midwest, in-field research is underway focusing on soil conservation and production.

The primary goal of the research, checkoff-funded through the Illinois Soybean Association, is to evaluate whether growers can maintain productivity and profitability while using reduced tillage and cover crops, systems that protect soil but are often perceived as risky.

A second objective is to understand whether starter fertilizer — nitrogen plus sulfur — could offset early-season challenges in these systems, such as cool soils, heavy residue and slower early growth.

Giovani Preza Fontes, University of Illinois Extension agronomist and research lead, detailed the preliminary findings from the first two years of research in an Illinois Nutrient Loss Reduction podcast with host Todd Gleason and producers Rachel Curry, Nicole Haverback and Luke Zwilling.

The trials include utilizing no-till, strip-till, conventional tillage and cover crops. What have you learned so far?

When we think about soil erosion, either by wind and water, conservation practices such as reduced tillage and cover crops are well-established practices.

There is a body of work in the literature showing they are very effective at reducing soil erosion — and, not only that, but there is also agro-ecosystem benefits from those practices. You’re keeping the soil covered for most of the time with the cover crops.

There’s evidence that they’re helping suppress weeds, breaking pest disease cycles, improving nutrient cycling. Cover crops is a big component of our Illinois Nutrient Loss Reduction Strategy.

There is a lot of work that shows that we can reduce nitrate leaching losses in tile drainage with a grass cover crop. We know all the benefits, but then when we look at adoption, it’s relatively low.

My student, Federico Rolle, is leading this project with me. He looked at the USDA and Illinois Department of Ag data on percentage of no-till fields in the Midwest and Illinois.

In Illinois, the percentage of no-till cropland is relatively low. It’s about 15% on corn and about 35% on soybeans.

We know the benefits, but when I talk to people, there’s this perception that these practices are somewhat risky, mainly because they are often associated with potential yield penalties.

The field trials were conducted at six sites across central Illinois and north-central Iowa. What treatments were included in the trials?

We looked at different combinations of tillage systems with starter fertilizer for a total of 12 treatments. We looked at conventional till, it’s a two-pass, a fall chisel with a spring cultivator. That’s what most people are doing.

We looked at a strip-till in the fall, a no-till and a no-till with a cereal rye cover crop. Each of those systems were paired with a starter fertilizer strategy.

We also have an untreated control where we don’t have any fertilizer. We had a treatment where we applied nitrogen as urea ammonium nitrate and another treatment where we applied nitrogen plus sulfur as a blend of UAN and ATS, ammonium thiosulfate.

How did the soybeans respond to the treatments and what were the yield responses?

We did see some early-season responses as we would expect to see. On average, the soybeans that received starter fertilizer tended to look greener and they produce a little more biomass early in the season.

We took soybean samples early in the season and midseason to see how they perform throughout the season. We did see those early season effects, but then at midseason they kind of disappeared.

We took tissue testing at R2, and by that point we did not see any significant difference when we looked at nitrogen and sulfur concentrations on those tissue testing that we did.

An important point is that when we look at those concentrations, they were all above the critical level that we often see in the literature.

So, the data pretty much suggests that by midseason the soybeans were not nitrogen and sulfur deficient — even the ones that we did not apply nitrogen.

Even though we saw those early-season starter fertilizer effect, that did not translate to yield. We did not see any yield increases when we have the starter fertilizers.

But we did see differences in the tillage system practices. On average across six sites and two years, we saw that basically we were able to maintain soybean yields when we moved to some of those reduced tillage practices.

If you look at the average yield statistically, we did not see any significantly differences among the conventional till, the strip-till and the no-till.

We saw a slightly lower yields when we had the no-till with the cereal rye, but numerically that was just like two bushels compared to the conventional till. They all average about 76 to 78 bushels to the acre.

The research also included the economics associated with different tillage systems. What does that show?

We used those costs of tillage passes from our colleagues in ag economics. They have this handbook with the cost of tillage passes.

So, we only did this as a partial net return. We were only taking into consideration the cost of the tillage.

If you look at the partial net return, we did see higher returns with no-till because there are no expenses with no-tilling, followed by strip-till and conventional till.

We did see the lowest partial net return with the no-till with the cereal rye cover crop, and that was mainly associated with the higher cost associated with cover crop management.

That would have been the cost of the seed and the pass to get it on, correct?

Yes, planting, cost of planting seed and termination is estimated at $55 per acre versus strip-till, for example, which was estimated at $26 per acre. But again we try to make the argument that, and farmers know, everything we do on the field costs money.

We know there’s a big push for cover crops. We know the benefits and why we’re promoting it. But I think this is something that farmers usually ask me a lot on the economic side.

This is just partial net return on this, but it gives an indication that some of those conservation practices may come at an additional cost and there needs to be some discussion there. There are a lot of state and federal cost-share programs that can help offset some of those costs.

Will this research continue?

Yes, we’re working with a farmer in Piatt County and doing this work in his field. We established those trials in 2023 and we established a new field in 2024.

So, we have two fields now that we’re gonna keep rotating them between corn and soybeans. The plan is to have this for at least four or five years.

The caveat with this project is all those fields are kind of early years transitioning. They all came from conventional till and they’re transitioning to those systems.

This is what we found early in the first two years, but we’re going to keep doing that for at least four or five years to kind of see if things change as the system progresses and kind of stabilizes.