Which crop should be prioritized for early planting to get the greatest yield benefit?

Which to plant first? Corn or soybeans?

By Dusty Sonnenberg, CCA, Field Leader, a project of the Ohio Soybean Council and Soybean Check-off

In an epic and ongoing “Battle for the Belt” with Ohio State University Extension, researchers are digging into the question gaining increasing attention among Ohio’s corn and soybean growers. Which crop should be prioritized for early planting to get the greatest yield benefit?

“We can also look at the other side of the question, which crop has the smallest yield penalty for delayed planting,” said Laura Lindsey, OSU Extension Soybean and Small Grains Specialist. “Can we adjust our management practices to mitigate losses due to late planting? We don’t want to plant late, but sometimes weather conditions in Ohio dictate when we plant, which can be later than we like to see.” 

Delayed planting incorporates considerations beyond the weather.

“We need to look at interactions with insects, diseases, weeds, and many other factors. When you alter your planting date, you also alter the problems you may encounter in the growing season,” Lindsey said. “The planting date for both corn and soybeans is extremely important. On average in corn, we have seen a 1.75 bushels per acre per day loss if you plant after the end of April. In soybeans, we have measured about a half bushel per acre per day loss if you plant after the end of April. In some years the loss is more and some less depending on the year.”

Ohio soils and weather pose some unique challenges.

“The spring planting window can be very narrow. This can force farmers to plant earlier or later than when they would ideally like. The planting window continues to get smaller with fewer days each spring to conduct field work. According to Kansas State University, between April 17 and May 15 in Ohio there are an average of 15 suitable field workdays,” Lindsey said. “That means suitable for any field activities, not just planting.”

Osler Ortez, Assistant Professor, Corn and Emerging Crops said the research is spread out around the state.

 “The Battle for the Belt project was started in 2023 and will continue through 2025. The study is being conducted at three locations across the state with five planting windows. Those locations include Wooster at OSU/OARDC (Wayne County), the OSU/OARDC Northwest Research Station in Custar (Wood County), and the Western Research Station in South Charleston (Clark County),” he said. “The planting windows include Late March-Early April, Mid-Late April, Early to Mid-May, Late May–Early June, Mid-Late June.” 

Crop insurance also becomes a factor to consider in early planting decisions.

“Being knowledgeable of your specific crop insurance recommendations and deadlines for the earliest planting dates and latest planting dates should be factored into your decision making,” Ortez said. “On top of the planting dates, we looked at two other factors. For corn, the hybrid relative maturity dates were considered. We looked at four different maturities. Later plantings looked at a shorter maturity hybrid and for early planting we looked at a longer maturity hybrid. For soybean the relative maturity and varieties were considered when looking at seeding rates and adjusting accordingly with higher seeding rates for later planting dates.”

For the soybean plots, there were two that performed similarly in 2023.

“The Northwest and Western locations had a planting date effect, but no seeding rate effect,” Lindsey said. “Regardless if we planted 100,000 seeds per acre or 210,000 seeds per acre, the soybean yield was statistically the same. This tells us when you plant early to plant your normal target rate. In Wooster, there was a planting date by seeding rate interaction. That means that based on your planting date, you should adjust your seeding rate. What we saw with the first two planting dates in 2023 is that we needed a higher seeding rate. On April 14 and 27 we noticed a definite increase in yield as we increased the seeding rate. For the more normal seeding dates, the yields were statistically the same regardless of the seeding rate.”

In the earlier planting dates, the soybean plant populations were very low.

“On the April 14 planting date, we needed 210,000 seeds per acre to get a stand of 34,000 plants per acre,” said Lindsey. “The plant population from 210,000 seeds per acre on the April 27 planting date ranged from 22,000 up to 50,000 plants per acre.

“Interestingly, 34,000 plants per acre is a very low stand, and usually would warrant a replant situation. In this case it yielded 45 bushels per acre. This compared to the normal planting date stand which yielded in the 60s. Research shows that the replant threshold is 50,000 plants per acre. This year in a plot that had 68,000 plants per acre, the yield was statistically the same as those with a plant stand of over 100,000 plants per acre. In the later planting dates, the stands were good. What is interesting to me is that looking at the May 30 and June 21 planting dates, the plant stands were higher, but the yields were lower. Having an earlier planting date is more important than having a perfect stand of 120,000 plants per acre. If you fall in the 75,000-100,000 plants per acre with a good planting date, those soybean plants can really compensate and maximize yield.”

In general, for what was observed in Northwest and Western Ohio, it is okay to plant early (as soon as the crop insurance date allows) if the soil conditions are right. The crop insurance date for the location in Northwest Ohio is April 15 and the date at the Western Ohio location is April 10. In terms of the seeding rate, there wasn’t much effect.

“When planting early in Northwest and Western Ohio, you may be able to go as low as 100,000 seeds per acre planting early, but it is risky,” Lindsey said. 

A normal seeding rate should not be a problem when planting early. In Northeast Ohio, more caution is advised if planting early.

“From 1 year of data in this study and 2 years of data in a prior study, we had much lower plant populations and lower yields,” Lindsey said. “It tends to be cooler than our other locations.”

Soybean growth stage development across the locations was also observed in the study.

“When we plant early, we tend to have a longer vegetative stage. There is more plant growth and more nodes where pods can go,” Lindsey said. “The flowering stages of R1 and R2 are shifted later, but R3 and R4 are about the same length of time regardless of when you plant, just shifted later. The R5 and R6 growth stages tend to be elongated when you plant earlier. R5 and R6 are critical times to maximize yields. Longer grain fill periods with adequate moisture tend to help maximize the yields.”

From a crop insurance standpoint, corn in southern Ohio can be planted as early as April 5 and as early as April 10 in the northern part of the state.

In the corn, besides planting dates, we looked at hybrid relative maturity.

“We looked at four different maturities, including 100, 107, 111, and 115 relative maturity corn. If we plant later in the year, it makes sense to consider planting a shorter maturity corn and if we plant early, it makes sense to plant a longer maturity corn,” Ortez said.

The corn had different dynamics relative to the soybeans. Corn and soybeans were planted on nearly the same dates as the soybeans at the three locations.

“We did see an interaction between the planting date and hybrid,” Ortez said. “For a given planting date, we will be looking at different hybrid maturities to optimize the corn yield.

“In order to maximize the yield at the Northwest Ohio location (Wood County), both the 111- and 115-day maturity corn performed well as long as we planted early. The three earliest planting dates yielded very similar. The 100-day relative maturity yielded the best when planted at the latest planting date,” Ortez said. “If we are planting later in the year, we might want to consider adjusting those relative maturities in corn. We don’t want to go early with a short maturity, but late we may want to consider it.”  

In Northeast Ohio, (Wayne County, Wooster location) the May 11 planting date with the 107- and 115-day relative maturity corn yielded the highest.

“If we planted early or if we planted later, we saw lower yields. This is different than what we observed in Northwest Ohio. In Northwest Ohio, corn had an advantage planting early, in Northeast Ohio this was not necessarily the case,” Ortez said.

The Northeast Ohio location had some unique conditions with being wet and cold.

In Western Ohio (Clark County) the conditions were more challenging.

“If you planted corn in the first three dates in Clark County, that is when the corn yielded the lowest, regardless of the maturity,” Ortez said. “This location challenged the notion that planting corn early would give us the highest yield. That did not happen for the 1 year, one site trial.”

The best planting date and maturity for the Western Ohio location was the 107-day corn planted on May 25.

“It yielded almost 275 bushels per acre. This location had a very dry period from Mid-May to Mid-June that hurt the earlier planted corn. The later planted corn at this location had good precipitation to help the last two planting dates,” Ortez said.

Based on the first year of results, it is best if corn is planted as soon as possible with a full season 115-day hybrid in Northwest Ohio. In Northeast Ohio, the best yield was the May 11 planted corn with the 107- or 115-day relative maturity corn. In Western Ohio, the benefit was when corn was planted later due to the first wet and then very dry weather conditions and the greatest yield was the 107-day corn planted on May 25.

Comparing the two crops overall in the first year of the project, the results varied by location. Across the state the top corn yields were 250 bushels per acre and top soybean yields were near 100 bushels per acre. In Northwest Ohio, corn yields were maximized around the May 11 planting date. For soybeans, the yields were maximized at both the first and second planting dates.

The main takeaway is that the corn yield declined rapidly after May 11 compared to soybeans. The yield penalty for planting corn late was greater in soybeans in Northwest Ohio.

In Northeast Ohio, corn and soybeans both suffered from early plantings. For soybeans it had to deal with plant populations and for corn it was the stressful locations. Both corn and soybeans were maximized at the May 11 planting date. Similar to Northwest Ohio, the corn had a rapid decline in yield if planted after the May 11 planting date.

In Western Ohio, generally corn will yield better if planted earlier. This year it was not the case. There were stressful environmental conditions. Soybeans are typically a resilient crop relative to corn and can withstand colder temperatures and wetter conditions.

“In Western Ohio in 2023 for soybeans it did not matter if they were planted in early or mid-April or early-May. They yielded the same,” Lindsey said. “For corn it was opposite from what one would think. Corn yields were higher as you planted later at this location in 2023.”

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