Corn Management Factors with The Largest Impact on Yield in 2024

INSIGHTS

• On average, sidedressing nitrogen (N) had the largest impact on yield in 2024 trials, although response was dependent on location.
• Favorable growing conditions in 2024 resulted in consistent responses to moderate-high seeding rate increases.
• Selecting the right hybrid, matched with the optimal seeding rate, and utilizing a systems approach to management was the key to achieving high yield.

Crop Management Practices Trial Parameters

Figure 1. Visual growth difference between base treatment (left) and combination treatment (right) at Clinton, IL in 2024. Combination treatment would have received additional fertility at planting and sidedress N when image was captured.

Corn production is a complex and dynamic process that requires farmers to make numerous critical decisions throughout the year. These decisions can significantly impact yield potential and profitability. Yearly differences in environment and weather make these decisions even more challenging.

In 2024, the Golden Harvest Agronomy in Action research team implemented a trial to understand which core crop management practices had the largest impact on corn yield across six Midwest locations. The core management practices evaluated were:

1. Incremental Fertility: 17 N, 35 P2O5, 32 K2O, 17 S, and 0.14 Zn lbs per acre banded with the planter.
2. Sidedress N: 60 lbs/A of N applied as 32% UAN surface-banded along the base of the plant at the V5 growth stage.
3. Fungicide: Miravis^® Neo (13.7 oz/acre) foliar fungicide applied at the R1 growth stage.
4. Seeding Rate: 32,000, 36,000 or 40,000 seeds/A.

The fertility, sidedress N, and fungicide treatments were each individually added to the base management system at all three seeding rates to determine what impact they had on yield. In addition, all treatments were applied in combination to evaluate potential synergistic effects with intensive crop management. The fertility and sidedress N treatments were added incrementally to the grower’s normal fertility program. Two hybrids were used at each location, either G01U74 and G03U08 brands or G10U97 and G13U96 brands, depending on the geography.

Values represent yield difference (Bu/A) compared to the base treatment.
* significantly different than base treatment at α=0.10.
Table 1. Effect of management factor on yield averaged across seeding rate and hybrid at 6 locations in 2024.

Management Effect on Yield

Yield environments ranged from 220 Bu/A at Grundy Center, IA, to 290 Bu/A at Clay Center, KS. Crop management had a significant effect on yield at all locations. When averaged across locations, 3 seeding rates, and hybrids, each management factor individually significantly increased yield. Fertility increased yield by 4 Bu/A, sidedress N by 8 Bu/A, and fungicide by 6 Bu/A (Table 1). The combination of all three treatments applied together had an additive effect and boosted yield by 16 Bu/A.

Slater, IA, was the only location that had a significant response to incremental fertility, increasing yield by 13 Bu/A (Table 1). It was also the only location that had low soil test potassium levels (165 ppm). All other locations were considered to have adequate phosphate and potassium soil test levels. Fertility was the single factor that provided the highest yield response when it was limited illustrating the importance of implementing a solid base fertility program before considering additional management.

Applying an additional 60 lbs/A of N at the V5 growth stage increased yield by 4 to 11 Bu/A, depending on the location. N also provided the largest yield response of any single factor at 4 out of the 6 locations (Clay Center, KS, Clinton, IL, Grundy Center, IA, and Janesville, WI, Table 1). All locations experienced above-average precipitation during May and June, likely moving preplant N below the rooting zone. Plants benefited from additional N applied in-season.

Overall, disease pressure was low across sites. Yield response to fungicide ranged from 1 to 13 Bu/A across locations (Table 1). Only corn grown at Clinton, IL, and Malta, IL, had a significant response of 10 and 13 Bu/A, respectively. Corn at Clinton, IL had some gray leaf spot but it did not progress up the canopy. Malta, IL had tar spot but did not show visual symptoms until the late grain fill period, likely having minimal impact on yield. The response to fungicide is likely driven by the increase in plant health and stay-green effect, prolonging the grain fill period.

When all three management factors were applied in combination, yields were increased by 11 to 25 Bu/A depending on location (Table 1). 3 out of the 6 locations experienced a synergistic effect where the yield increase from the combination treatment was greater than the sum of yield gains from each individual factor. A synergistic effect often occurs because early season management can help set a higher yield potential and later season management maintains that yield potential by aiding with grain fill. A systems approach, rather than one individual management practice, is the key to achieving high yields.

Different letters within a location illustrate significant difference at α = 0.10.
Graph 1. Effect of seeding rate on yield averaged across management factor and hybrids at 6 locations in 2024.

Seeding Rate Effect on Yield

When averaged across location, hybrid, and management factor, seeding rate had a significant effect increasing yield by 1 Bu/A for every additional 1,000 seeds/A from 32,000 seeds/A up to 40,000 seeds/acre (Graph 1). Overall, growing conditions were favorable across all locations with adequate moisture for much of the growing season. It tended to get drier in late August and September but yield environments were still high. Favorable growing conditions this season minimized much of the stress often seen with higher plant densities, resulting in a greater response to seeding rate than what is typically seen. The Clay Center, KS, and Janesville, WI, locations were the most responsive to seeding rate, with greater yields achieved as seeding rate increased (Graph 1). Slater, IA, was the only location that had no significant response to seeding rate. Interestingly, there was no interaction between management practice and seeding rate. Regardless of management system, corn had a similar response to seeding rate.

Hybrid Response to Management and Seeding Rate

G01U74 Brand

G01U74 responded to all three management practices, but the 16 Bu/A yield response from sidedressing N was greater than other practices (Table 2). The 22 Bu/A response from combining management practices was higher than other hybrids, implying overall responsiveness to management. Seeding rate for G01U74 was optimized at 36,000 seeds/acre, whereas other hybrids benefited more from incremental seeding rates (Graph 2). This trial suggests planting G01U74 at a moderate seeding rate and ensuring N is not limited will help maximize its potential.

Different letters within a location illustrate significant difference at α = 0.10.
Graph 2. Hybrid yield response to seeding rate averaged across management factor and location in 2024.

G03U08 Brand

G03U08 had minimal response to individual management practices, however when combined, a significant 15 Bu/A increase was observed (Table 2). Yields steadily increased by 7 and 4 Bu/A with each increase in seeding rate (Graph 2). G03U08 yields were maximized when seeding rates were raised in combination with fertility, N and fungicide applications. In these trials, G03U08 responded best to a systems approach to management.

G10U97 Brand

G10U97 had comparable 5-6 Bu/A responses from individual management practices (Table 2) and moderate yield increases from increased seeding rates (Graph 2).

G13U96 Brand

G13U96 had one of the largest responses to fungicide and sidedress N (Table 2). Its response to incremental fertility was similar to other hybrids. G13U96 was generally less responsive to small incremental seeding rates but did benefit slightly from an 8,000 seeds/A increase. Utilizing in-season supplemental N and maintaining plant health with a fungicide drove the biggest yield responses with G13U96 in this trial.

Values represent yield difference (Bu/A) compared to the base treatment.
* significantly different than base treatment at α=0.10.
Table 2. Hybrid yield response to management factors averaged across seeding rate and location in 2024.

Summary

In crop production, no year is considered a “normal” year when it comes to the weather. With above-average precipitation in 2024 during May and June, sidedress N provided the greatest increase in yield on average. Fungicide was also an important player in 2024 to improve plant health and prolong the grain fill period. Fertility cannot be overlooked, and is the foundation of corn production. Low soil test levels must be addressed first.

Understanding hybrid response to management and seeding rate is critical to maximizing hybrid performance. Selecting the right hybrid, matched with the optimal seeding rate, and utilizing a systems approach to management is the key to achieving high yield.