Corn growers in the Midwest are testing whether they can use less nitrogen fertilizer and still maintain yields or improve their bottom line through on-farm research trials. It’s part of an ongoing project led by Practical Farmers of Iowa (PFI).
Farmers from Illinois, Iowa, Minnesota, Missouri, Nebraska and Wisconsin who have used cover crops, no-till or other soil health practices for at least five years can participate.
The project stems from a growing body of research showing crops often require less nitrogen fertilizer to thrive as organic matter and other metrics of soil health improve.
Since synthetic fertilizer is one of the biggest costs in crop production, PFI staff said cutting back could improve farmers’ net returns while lowering greenhouse gas emissions and nutrient runoff.
Nitrates that are not absorbed by plants easily move with groundwater and through field tiles, which can pollute drinking water and fuel algal blooms.
Participants in the PFI research trials apply their typical nitrogen fertilizer rate and a reduced rate in randomized strips in their fields. They then share data with PFI to compare yields, costs and profits.
Results from 2023 show most of the field trials with lower fertilizer rates “potentially saved money” compared to one-third in 2024. Roberta Bianchin Rebesquini, PFI senior cropping systems research coordinator, expects results from 2025 to be posted online next month.
The project, which is supported by PepsiCo and the Foundation for Food & Agriculture Research, compensates farmers who participate. Bianchin Rebesquini said enrollment will likely stay open until early April.
Results from southern Iowa
Kevin Prevo raises livestock and grows corn, soybeans, rye and straw on 1,400 acres near Bloomfield, alongside his parents, two brothers and their families. Since 2014, they’ve integrated cover crops and no-till across 100% of their crop acres. Prevo said their main motivation was improving soil health to allow more water infiltration.
“My grandpa always said, ‘In Davis County, we’re two weeks away from a drought,’ and I guess our goal was to make that three weeks or a month without a rain and not lose a crop,” Prevo said.
Reducing soil erosion in the rolling hills of southern Iowa was another reason for incorporating cover crops and no-till, he said.
This will be his family’s fourth year participating in the on-farm research trials.
“As far as manure rates, we have seen we’re able to lower those rates … and not really hurt yield,” Prevo said. “In general, it seems like our soil health practices are working.”
Prevo added that soil type and weather can affect outcomes, and he appreciates seeing data from other farmers participating in the nitrogen rate research trials.
Sean Dengler, a crop nutrition coordinator at PFI, said another option for farmers interested in reducing their fertilizer use on a larger-scale is the N Rate Risk Protection Program.
A PFI agronomist suggests an optimal, site-specific fertilizer rate. Farmers receive $5 per acre enrolled, and if yields drop, that bumps up to $30 per acre.
Dengler described it as an insurance program.
“You can make the changes and then be guaranteed if something goes wrong that you’ll get some money back,” he said. “But more than likely, you’ll probably realize, ‘Hey I can save a little money on this. I don’t have to put down as much nitrogen.’”
Dengler said that can reduce farmers’ input costs, along with risks of nitrogen leaching out of fields and into streams, rivers and lakes.
