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Late Start on Planting May Not Hurt Yields Much

May 17, 2019

Despite rain that has stalled the planting of corn and soybeans across the state, yields might not be reduced, according to two grain specialists at The Ohio State University.

That’s because weather later in the growing season can have a bigger impact on yields than the date the seeds go in the ground, said Peter Thomison and Laura Lindsey, both agronomists at Ohio State’s College of Food, Agricultural, and Environmental Sciences (CFAES).

During July and August, too much or too little rain or really hot temperatures can be detrimental because that’s when corn plants form kernels and soybean plants form beans, Thomison and Lindsey said.

Only 4% of this year’s corn crop has been planted compared to 50% this time last year; 2% of the soybean crop has been planted compared to 28% this time last year, according to a U.S. Department of Agriculture report released May 13.

During the week that ended May 12, only 1.5 days were suitable for fieldwork due to rain or ground saturation. Planting in soggy ground can lead to soil compaction, and seeds tend to develop shallow root systems.

“I think a lot of people would like to be done planting right now,” Lindsey said. “But there’s been several years where it has dragged on.”

In 2017, though corn and soybeans were planted early, some had to be replanted in June because of excessive rain that reduced plant stands, Thomison said. Yet, the state had record high yields for both crops that year.

So, the situation is not yet critical. And farmers don’t yet need to switch to planting a shorter-season variety of corn seed, Thomison said. Corn varieties of varying maturity can adjust their growth and development in response to a shortened growing season, he said.

“I don’t want to be a fear monger,” he said. “If we get our corn planted in late May or early June, and we have good growing conditions, we could still end up with a very good crop.”

In 2011, only 19% of Ohio’s corn crop had been planted by May 30, but the yields were the same as the five-year average, Thomison said.

Soybeans tend to have higher yields when they are planted between the end of April and early May, Lindsey said.

“I want to tell growers not to worry, but it’s hard not to worry,” she said. “It’s hard to wait.”

Soybean farmers can take some measures to try to ensure good yields even with a late start on planting.

If farmers don’t end up being able to plant until sometime in June, they might want to increase the number of seeds per acre from 140,000 to 150,000 or 160,000, Lindsey said.

When planting soybeans in June, making rows that are 7.5 to 15 inches wide can be helpful, Lindsey said. Rows of that width typically produce higher yields than wide rows of 30 inches or so, and the effect becomes even greater when soybeans are planted later, she said.

Narrow rows typically bring greater yields because as the soybean plant grows and its branches and leaves spread out, the canopy covers up the dirt between the rows. That allows little to no soil to be exposed to direct sunlight, which keeps the temperature in the soil down and maintains moisture in the soil.

Selecting the latest-maturing variety of soybean seeds that will reach maturity before the first killing frost can also help compensate for a delayed planting date, Lindsey said.

And it’s important to remember, soybeans are very resilient plants, she said.

“Despite bad weather, they can still maintain relatively good yield.”

Source: Ohio State University