It’s almost time. So, what’s your agronomic game plan as planting commences in 2025?
For Robb Ewoldt, it’s all about growing more bushels.
“We’re looking at things that can enhance yield,” the Davenport, Iowa, farmer and United Soybean Board director says. “The higher yields we get, the lower our breakeven cost is.”
With this in mind, we rounded up 12 questions (and answers) about how to boost yields and/or increase return on investment for 2025.
1. Should I plant corn or soybeans first?Well, it depends.
Soil temperatures of 50 degrees F followed by four to five days of forecasted good weather bodes well for planting corn, says Andrew Penney, a Bayer Preceon agronomy lead.
Conversely, soybeans gain the nod if soil temperatures hover around 48 to 49 degrees F with an adverse four- to five-day weather forecast.
“Soybeans can germinate in temperatures lower than those of corn,” Penney says. “We can tolerate losing a few soybeans plants. With corn, losing a few plants matters a lot more.”
2. How can I deal with variable weather?You remember the drill from 2024. A dry April was punctuated by May monsoons that didn’t fully cease in some areas until early July. For the most part, rainfall then ceased to create a bone-dry harvest.
What to do? “It’s important to choose hybrids and varieties that can tolerate wet feet but also have good drought tolerance,” Penney says.
3. What direction should I take for variable rate soybean populations?“With soybeans, we want to drop populations in highly productive areas,” Penney says. “This can save seed costs while maintaining yield.”
It’s a different story in poorer field areas, however. “In those spots, we want to raise populations to increase plant-to-plant competition, plant height and branching so that the canopy can close quicker,” Penney says.
4. How can I stop waterhemp from gaining a foothold in my fields?“The earlier you can get something on from a preemergence perspective, the better,” says Will Griffin, row crop segment manager for Valent USA. A strong preemergence herbicide mix featuring multiple sites of action can effectively halt grasses and broadleaves such as waterhemp for several weeks until an overlapping postemergence residual can take over.
UGH, IT’S WATERHEMP: This pesky pigweed quickly squelches yields when it comes to this stage. However, preemergence residual herbicide products followed by a postemergence residual herbicide mix can keep it at bay. (GIL GULLICKSON)“If we’re able to keep a field clean and stop weeds from going to seed, the likelihood of heavy weed pressure the following year is reduced,” he says.
5. Should I split nitrogen applications?
Yes.
“If all nitrogen is put on upfront and wet weather results, there’s the potential to lose a lot of it,” Penney says. “No one wants to see their nitrogen move deeper into the soil profile, where the plant can’t access it. The more we split up applications of nitrogen, the better off the return on investment will be.”
6. Do modern hybrids influence this?
Yes. “We're planting later-maturing corn that captures additional yield because of heavier kernel weight,” Penney says. “To get that heavier kernel weight, we need more nitrogen later in the growing season. All the science shows us that we need more nitrogen later, and yet we're still putting a lot of our nitrogen on in a one-pass system.”
7. How do I know I’m applying the correct N sidedress rate?
“Last year, March was the demise of many fall nitrogen applications,” says Andrew Luzum, Corteva nutrient maximizer strategic account manager.
That’s because warm soil temperatures triggered the nitrification process in which anhydrous ammonia converts to nitrate. In this stage, N is prone to losses through leaching through the soil profile or de-nitrification into the atmosphere. In such environments, it becomes apparent which N is protected through N stabilizers, Luzum says.
If weather conditions are prime to drive N loss potential, Luzum advises farmers to sample fields with late-season nitrate tests in order to ensure optimum sidedress N rates.
“Samples we pulled last year were amazing,” he says. “Some [sidedress] recommendations were up to 100 pounds [of N per acre], while others only called for rates of 20 pounds [of N per acre].”
8. Should I apply starter fertilizer?
Many Iowa soils are rich in phosphorus, which starter fertilizers contain. However, P availability to corn can be lacking in cold and wet springtime soils.
“That’s where starter fertilizer can have a benefit,” Luzum says. The extra boost of P can help get corn plants off to a good start, he adds.
9. Should I expect tar spot in 2025?
Yes. Last year heralded the spread of this new corn fungal disease into more areas.
“There will be plenty of inoculum,” Penney says. “We already have the scenario with spores out there and just need adequate moisture to give us the right conditions for the disease to take off.”
TAR SPOT TROUBLES: This fungal disease expanded its reach in 2024 and threatens to spread more in 2025. Hybrid selection, a sound fertility plan and fungicides are ways farmers can manage tar spot. (IOWA STATE UNIVERSITY)10. How can I best manage tar spot?
Genetically resistant hybrids are the first place to start, Penney says.
The second is keeping the plant healthy, he adds. A stressed plant has little ability to battle tar spot and other diseases. A finely tuned fertility plan can help corn better tolerate diseases such as tar spot.
If environmental conditions are conducive for tar spot around VT [tassel], apply a fungicide, Penney adds.
11. Is VT the best time to apply a fungicide?
In most cases, yes. Optimum timing normally occurs around VT. However, weather conditions can alter this timing, Penney says.
“I always tell growers that if it has been dry two weeks prior to tassel and the forecast is for dry weather, you can delay the application to ensure protection later into grain fill,” he says. In such cases, he recommends waiting until R2 [blister stage] to consider applying a fungicide.
However, this hinges on a farmer’s ability to schedule a timely aerial application, or if a farmer owns a ground rig to quickly apply a fungicide, he adds. If a farmer is at the mercy of a commercial applicator, aim for the VT timing, Penney says.
12. Does a two-pass fungicide application pay?
In most cases, no, Penney says. Still, conditions that spur tar spot infestations over long periods can result in applications at VT and R3 spurring a favorable return on investment, he says.
“Even at the R5 stage, you still have corn kernels that need to accumulate roughly 45% dry matter to maximize yields,” he says. “That is 45% of your yield.”
If tar spot infestations continue, an R3 fungicide application can protect yields later into the growing season. However, if corn enters into the R4 and R5 stages, it is getting too late for a fungicide application, Penney says.