What happens in cornfields that yield over 250 bushels per acre that doesn’t happen in cornfields yielding under 150 bushels per acre?
Mark Jeschke, agronomy manager for Pioneer, says a team of Corteva Agriscience researchers were determined to find out. They looked at measurements of plant biomass and nitrogen content from a series of experiments conducted by Corteva over a 13-year span, from 2011 through 2023. The team included Rebecca Hensley, Andrea Salinas, Andres Reyes, Christian Michael Navarro, Logan Anderson and Jason DeBruin. Their complete findings were published in the 2025 Pioneer Agronomy Research Summary.
The researchers separated yield into four categories, and then compared plant biomass and nitrogen traits for each plot by category. The four yield categories were: less than 150 bushels, 150 to 200 bushels, 200 to 250 bushels, and over 250 bushels.
They truly wanted to see what set those high-yielding fields apart, Jeschke says. Besides measuring biomass and nitrogen levels, they also evaluated leaf area index, kernel number, kernel weight and silk number, plot by plot and yield category by yield category.
Silk number was the only variable that didn’t differ significantly. The difference, as noted below, came in number of silks fertilized.
What researchers learned
Here are four key differences that set higher-yielding fields apart:
1. More nitrogen uptake late. Higher-yielding fields relied more on nitrogen uptake during grain fill compared to lower-yielding fields. It is common for plants to remobilize nutrients from the stalk and other parts to finish filling kernels. However, in the highest-yielding fields, less nitrogen for grain fill came from remobilization, with more resulting from roots taking up nitrogen from the soil.
2. Larger leaf area. Does higher-yielding corn need a bigger factory? Results support that idea, Jeschke notes. Leaf area index increased with each successive yield class.
Differences weren’t subtle. Leaf area index was 4.4 for corn yielding under 150 bushels per acre, and 6.1 for fields over 250 bushels. That is nearly a 40% increase. Average leaf indexes for the 150 to 200 and 200 to 250 categories were 5.0 and 5.7, respectively.
3. Maximized kernel number. Fields yielding 200 bushels or more exhibited maximum kernel number vs. plots below 200. Kernel number for the 200 to 250 category, at 561 per ear, was slightly higher than yields over 250, at 549. However, kernel count for the under 150 yield level and 150 to 200 category were 400 and 492, respectively.
“Basically, at yields of 200 or more, all expressed silks were fertilized and developed into kernels,” Jeschke says. Incomplete kernel set sacrificed potential in lower-yielding fields.
4. Heavier kernel weight. This factor differed the most among categories, rising with each successive yield increase, Jeschke reports. Kernel mass, in milligrams per kernel, increased from 222 at under 150 to 327 at over 250.
Kernels per bushel, a key factor in corn yield estimate formulas, puts this in perspective. Modern hybrids typically run around 80,000 kernels per bushel. Here, kernels per bushel ranged from 100,000 for yields under 150 to 67,000 for yields over 250, a huge difference. Numbers for 150 to 200 and 200 to 250 were 85,000 and 75,000, respectively.