The short growing season in the North means a small window for planting. Unfortunately, current literature suggests the optimal planting dates for corn and soybeans occur at the same time.
If planted after the end of April, corn can suffer a loss of 1.75 bushels/acre/day. Soybeans can suffer 0.5 bushels/acre/day, according to Laura Lindsey, soybean and small grain Extension state specialist with Ohio State’s Horticulture & Crop Science Department. Lindsey presented on the topic at the recent Soybean & Small Grains Congress hosted by Cornell Cooperative Extension’s Northwest Dairy, Livestock & Field Crops Program.
Framing it as an athletic competition – a “Battle for the Belt” – Lindsey presented her two years of research on the topic “Which should you plant first, corn or soybeans?”
As to the end of April deadline, Lindsey said that seasonal variability plays into the decision, as do shifts in temperate weather.
“Our planting window in Ohio is extremely small and getting smaller,” she said. “We had a drought last year and it flooded after the drought.”
She noted that since 1995, the field days of work during planting time (April 17 to May 15) have decreased from 22 to 15 in Ohio.
“New York had 22 suitable workdays, but the trend is fewer and fewer,” Lindsey said.
The dates are also shifting about 10 days sooner because of earlier warmth, which Lindsey said is a good thing for optimizing crop yields, but it also can be challenging because of wet fields.
Choosing to plant corn or soybeans first also relies upon which crop levies the heavier “penalty” for delayed planting.
“Can we adjust management practices to mitigate losses due to late planting?” Lindsey asked. “How are insects, diseases, weeds and other factors affected by planting date?”
Farmers should also pay attention to crop insurance dates.
Seeding rates can make a difference in yield when compared with relative maturity. For example, 100,000 soybean seeds are recommended per acre with 100-day relative maturity, but 210,000 seeds/acre are recommended for 115-day relative maturity.
“The reason for our high planting rate was our plant population was very poor,” Lindsey said.
Laura Lindsey, soybean and small grain Extension state specialist with Ohio State’s Horticulture & Crop Science Department, presented on planting dates at the recent Soybean & Small Grains Congress hosted by CCE’s Northwest Dairy, Livestock & Field Crops Program. Photo by Deborah J. Sergeant
While undertaking her study, Lindsey noted that planting dates were hampered in 2024 by wet weather. Even if the soil temperature is the ideal minimum planting temperature of 50º F, waiting to get in the field is necessary.
In the 2023 season, she divided areas of the soybean test fields by planting date and seeded at different rates based upon the planting dates: April 14 and April 27, more than 210,000 seeds/acre and May 11, May 30 and June 21, 100,000 to 200,000 seeds/acre.
Disease, pests and cold likely influenced the resulting low stand.
“We pull seedlings to look at pathogens,” Lindsey said. “We saw corn seed maggot.” The corn seed maggot damaged soybean seedlings from the first planting date, which affected germination.
Lindsey said that in 2024, the group that was planted by May 11 proved the best-producing test plot. She called it a “boring year for an agronomist, but that’s a good year for a farmer.”
For the corn trials in 2023, the planting dates and relative maturity for April 14 and April 27 were 115 days of relative maturity. For May 11, it was 107 and 115. For May 30, it was 100 and 107 and for June 21, it was 100 and 111.
For the corn trials in 2024, the dates pushed out a little. For April 22 and May 3, relative maturity was 115. For May 21 and June 4, it was 100. For June 20, it was 115.
“The longer relative maturity is good,” Lindsey said.
As for the “Battle for the Belt” in northeastern Ohio, an area close in weather trends to the rest of the Northeast, Lindsey called a tie between corn and soybeans. She advised growers to plant soybeans as soon as possible after the crop insurance early planting date if soil moisture conditions permit. As for corn, plant when soil conditions are optimal.
“Waiting until May seems the most consistent, but you may go earlier some years,” Lindsey said.
The top performer was the 115-RM corn in early planting dates.
“We’ll do it again in 2025 to see how it goes,” Lindsey said.
She said that areas north of Ohio are not areas where she would “most aggressively push on early planting dates.”
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