Tighter margins, smarter inputs

Marginal cost-and-return analysis is trickier as more variables are introduced into the equation. For example: the yield impact from changing in seeding rates is easier to quantify than changing to less expensive seed. “The higher priced seed may have more disease resistance, be more resistant to drought, or just have higher yield potential,” says Mike Langemeier, Purdue ag economist. 

For soybeans, a North American analysis published in 2019 showed that economic soybean seeding rates ranged from 66 to 80% of the optimal agronomic soybean seeding rate. One rule of thumb for Wisconsin, according to University of Wisconsin (UW) soybean specialist Shawn Conley, is to reduce seeding rates by about 20% in higher-yielding acres and increase rates by 20% on lower-yielding acres, “especially in areas of high white mold concern,” he says.

Most Corn Belt producers have already been fine-tuning seeding rates. (More details are available in this 2024 article.) That means many have been looking harder than ever at their nutrient programs in 2026, especially nitrogen.

Corn N: Know residuals

The same rules of marginal cost-and-return analysis apply to fertilizer inputs. If costs increase enough, past rates may no longer be justified. That means the basics are even more important than ever.

Higher nitrogen costs underscore knowing residual nitrate and ammonium levels. “I think the most important part in terms of nitrogen management is to remember what you already have,” says Rachel Henry, CCA/CPAg and water quality extension associate with The Ohio State University.

Producers in northwest Ohio are often surprised by fall residual levels, says Henry. “Especially if you’ve never had nitrogen deficiency, you might not be counting what you have to start with,” she says. “Extra N may have been applied, or maybe there’s some there that you’re not taking into account.”

In Iowa, the Iowa Nitrogen Initiative (INI) annually reports Iowa residual N levels. “The INI continues to reinforce something we all know but sometimes forget: optimum nitrogen fertilizer rates can vary by more than 100% from field to field and year to year,” says Daniel Andersen, Iowa State University ag engineer.

The INI tests in 2025 and 2024 showed that variability. Nearly all Iowa sites tested in 2024 had less than 25 lb of N in the top 12 inches of soil. In 2025, between one-third and one-half of sites tested above 25 lb N/ac. “That variability is where management opportunity lives,” says Andersen.

The INI has developed N-FACT, a nitrogen fertilizer decision tool for Iowa producers. “While it is currently only applicable to Iowa, it helps us understand some of the factors that may be driving site-to-site and year-to-year differences in the economic optimum N rate,” says Andersen. “Especially in places where they may have been dry over winter and fall, the residual N impact (from last year) might allow us to make better fertility decisions if we are willing to measure and take credit.”

Maximize return to N

A decision tool available to all producers in the Corn Belt is cornnratecalc.org, which calculates maximum return to nitrogen (MRTN). Such calculators can help simplify marginal cost/revenue analysis. But remember: any analysis depends on the information used. For MRTN, be sure that you or the producers you advise are counting any residuals. “The MRTN can be a starting point or a comparison point. But it’s super important to tie things to what rates you have been using in the past,” says Rachel Henry.

Henry conducted field research in 2024 to verify the MRTN was providing sound guidance for corn following a cereal rye cover crop. The results showed that the MRTN rate, which was 160 lb/ac, was the most profitable. But the results also illustrated the value of a marginal cost-and-return analysis: The MRTN rate did not have the highest yields or best N use efficiency. “This can be overlooked as the MRTN rate provided the highest returns over N, thus making the producers more money,” wrote Henry, in the project summary.

Counting what you have: cover crops

Like postharvest residual N levels, the benefits from cover crops over time can also be surprising. In northwestern Ohio, Rachel Henry works with one producer who annually samples biomass from his cover crop cocktail of 12 to 16 species. Nitrogen calculated from the biomass averaged 152 lb/ac per year from 2020 to 2025; however, the annual value ranged from 106 to 225 lb.  “In 2025, he applied 120 pounds of N per acre for the whole year, and his corn yielded right at the county average,” says Henry.

Cover crops to reduce soybean weed control costs?

In any year, producers are mulling possible ways to reduce weed control costs and cut down on applications. Even in the tightest margin years, a back-to-the-basics approach can be best: good crop scouting, correct timing, and all the other parts of a sound agronomy program.

More recently, cover crops have also emerged as a possible tool to reduce weed control costs and weed pressure. Corn Belt research in this area has focused on cereal rye (winter rye). “Cereal rye isn’t a silver bullet, but when properly managed, it’s a powerful tool in the weed management toolbox, reducing herbicide pressure, slowing resistance development, and improving the sustainability of Wisconsin cropping systems,” wrote UW weed scientists Rodrigo Werle and Guilherme Chudzik, in recommendations published on the Badger Crop Network.

The Wisconsin trials showed later termination of cereal rye in early planted soybean maximized suppression of waterhemp and giant ragweed without hurting soybean yield. At least 3,500 to 4,500 lb/ac of dry cereal rye biomass are needed to suppress waterhemp and giant ragweed, according to the Wisconsin research.

The Wisconsin trials found a 3,500-lb cereal rye biomass when the cover crop was terminated at heights of 19 to 26 inches. Cereal rye heights of 31 to 33 inches yielded 4,250 to 4,500 lb of dry biomass.

Control from the cereal rye cover crop also required an effective preemergent soil residual herbicide program. And the UW researchers found general soil health and resilience benefits from using cereal rye cover crops for five years or more.

Reducing costs: To test or not to test?

One way that producers look at cost-cutting, to increase the bottom line per acre, is the amount spent on various testing and crop-consulting services. The value of some tests may vary by region—even by field. One example in Ohio is the pre-sidedress soil nitrate test (PSNT). “It’s a mixed bag here when it comes to PSNT test before sidedress,” says Rachel Henry.

That can especially be the case in fields with cover crops, which can affect PSNT reliability. Starter nitrogen can also sway PSNT results, depending on where you pull the sample from. If you use PSNT—as for any other analysis or service—be sure the test is properly conducted and evaluate that data within the context of field history. “In our setting here in Ohio, the PSNT test doesn’t hurt—but it warrants some caution,” says Henry.

New products: to spend or not to spend?

Producers might also search for a yield boost by adopting newer products, such as fertilizer enhancers and biostimulants. Again, agronomists and ag economists point to using research-based data and a marginal cost-and-return analysis before spending to boost yields.

Phosphorus fertilizer enhancement products, some of which can potentially benefit soybean production in fields with soil pH extremes, are an example. For Wisconsin soybean producers, “Of all the products currently available, maleic-itaconic polymers have been studied the most extensively and have the best evidence for success when extremes in soil pH are present,” wrote UW soybean specialists, in January 2026.

More testing and research are needed to evaluate efficacy of the various phosphorus enhancement products, according to the UW team. Like so many other practices, any one product or practice should not be viewed as a silver bullet; agronomic basics reign supreme. “A strong nutrient management program based on the 4Rs remains the best strategy for long-term fertilization success,” they concluded.

The story is similar for new and novel soybean seed treatments. A study across 22 states, published in the December 2025 issue of Field Crops Research, looked at nine different biostimulant products commercially available for soybean seed treatment. The researchers found no significant yield differences between treated and untreated controls. “Agronomic practices affected yield more than any biostimulant products,” they reported.

The researchers, who conducted the project through the Science for Success soybean research network, did not write off biologicals. They cautioned the need for producers to understand the product biology and recommended they conduct their own on-farm trials before going “all in” on a new product.

It’s another example of how paying attention to agronomic and economic basics is a solid strategy for managing production costs in any season.