Genetics, luck helped protect 2023 yields

BLOOMINGTON, Ill. — How did that happen? Are we missing an opportunity for higher yields with genetic advancements?

How can that experience be put to use this year? Those are some of the questions after the surprising 2023 yields.

University of Illinois researchers Tony Studer, a geneticist, and Connor Sible, crop physiologist, provided their insights and recommendations in a recent Illinois Corn Connection podcast with Stu Ellis.

Despite adverse weather last year, including an extended dry period, Illinois corn averaged 206 bushels per acre and soybeans hit 63 bushels per acre, much to the surprise of many.

“I think part of it is just luck. We had very timely rains. There were times when I would walk into the field that I thought the crop might start to give up, and then we’d get a rain,” Studer said of the surprising yields last year.

“The timing of rain is so critical in the development and ultimate yield of corn and soybeans. We got lucky. I think that’s part of it, and I will attribute a lot of it to genetics.

“Over time, the genetics have gotten better on the side of resilience and stress tolerance. So, the plants are able to put roots down to really access the moisture that’s down there in our soils we have in Illinois.

“They’re more stress-tolerant to the point where they can hang in there when we’re not getting rain, they’re not aborting the kernels, they’re not sacrificing yield and that allows you, if you get that rain, to ultimately reach a pretty decent yield out of the crop.”

Fertility Changes?

With improved stress-tolerant genetics, the researchers were asked: If farmers boost fertility, will that translate to even higher yields?

“I don’t think so. I think really you’re dealing with from a genetic standpoint two different sets of genes. You’ve got the overall performance of the hybrid that’s going give you that upper yield, and then you’ve got that stress tolerance,” Studer said.

“The genes that are allowing that plant to hang in there aren’t necessarily the ones that are giving you a higher top-end, but they’re the ones that allow you to reach that yield potential.

“Just seeing it perform really well in a year that is bad doesn’t mean adding fertilizer is going to move that top-end yield level. It’s a different set of genes, different mechanisms in that.”

“There are places where we need that fertilizer nutrition, but it really does track down to the 4 Rs,” Sible added, citing the right source, the right rate, the right place and the right timing.

“Our traditional mindset of fertility is the soil test tells us what is potentially available for the crop, and then we look at removal rates — the total amount needed in the season.

“The perspective, though, is do you think that crop is using all that nutrition at the same time or is it using the same amount of nutrition the entire season. No, it’s the rates of nutrient uptake during the season that is so important.”

Using corn as an example, Sible noted corn could be at the V7, V8 growth stage and two weeks later “it’s above your head.”

“There’s that rapid growth pace on corn. Think about how much nutrition that crop needs in just that short two- to three-week window — can the soil supply keep up with that high demand? Probably not,” the crop physiologist said.

“So, while the soil test may be adequate from a total need, it’s ensuring you have the daily need, and that’s where things like in-season Y-drop or sidedress applications put the fertilizer out right at the phase of peak uptake, the phases where the soil supply is just not enough on a daily basis.”

“And that’s where I think we can start to push yields higher,” he said. “So, maybe not just more fertilizer, but thinking fertilizer placement and timing to match when the crop needs the most in a given day.”

Improved Yield Genetics

Besides improved stress-tolerant genetics, seed companies continue to improve genetics for higher yields.

That also does not translate to the need for more fertilizer. Instead, Studer said, the need is for more efficient nutrient management.

“So, putting that fertilizer where it needs to be when it needs to be there for the plant to grow, but then also on the genetic side how efficiently that plant is able to use nitrogen, for example,” he said.

“We’re not to the point yet where we need to increase the amount of fertilizer we’re putting down. The companies are doing a great job breeding and getting genetic gain in fertilizer use.

“Maybe not just more fertilizer, but thinking fertilizer placement and timing to match when the crop needs the most in a given day.”

—  Connor Sible, crop physiologist, University of Illinois

“Many decades ago, we were putting a lot of fertilizer on and saw yield bumps because that wasn’t happening previously. But over time, the trend bares out that we’re getting better and better, more efficient at using that nitrogen fertilizer.

“I’m not really ready to say that we need to add more fertilizer yet. I think the gain is still there and the potential for improved management strategies, the genetics being more efficient with the plant using the nitrogen and the grower sort of monitoring all of that in their system.

“They’re picking the seed. They’re doing the management. So, it’s the grower component, too, that matters.”

Placement

Corn roots go deeper into the ground beyond the top six inches during the growing season. That leads to the question of fertilizer stratifying away from the deep corn roots when sidedressing.

“In short, we are. The good news is most of our roots are in that top nine inches. The fine roots do go deeper and we get those roots that track into the deep soil, but the bulk of the root zone is in that nine inches,” Sible said.

“This is what we talk to our no-tillers about. After multiple years of no-till they see the nutrition is now in the top three inches, whereas our tilled system is in that zero to six inches because we work it in.

“So, that can be a challenge when the nutrition may be above the major root zone. New sources that move better are coming out, things like strip-till, placement, banded fertility — we’re really big proponents of banded fertility, putting it right where the root can get access to it.

“Why should we fertilize the whole soil when we’re skipping every 30 inches? It’s a great question and I think one we can increase efficiency on.”

Sible recommends fertilizer applications before and during the growing season.

“We do know from our nitrogen and phosphorus research that you need enough upfront to convince the plant it can set a high yield. It sets that yield ceiling pretty early in its life. So, for the first part, convince the plant is has enough to go for it,” he said.

“The second part is as that source starts to run out, make sure the plant has additional sources in-season to carry it all the way to the finish line.”