The 2024 growing season reenforced a trend: Early-planted soybeans tend to have a yield advantage. It’s not foolproof, but more times than not, the growing season that unfolds appears to favor early planting.

“We certainly saw that in Indiana and most of the eastern Corn Belt in 2024,” says Steve Gauck, a regional agronomy manager for Beck’s based near Greensburg, Ind. Beck’s sponsors Soybean Watch ’24.

“When harvest began, we saw high yield potential unfolding for beans planted in early to mid-April,” Gauck says. “In fact, weather patterns seemed to favor early-maturing varieties planted in April. They took advantage of July rains which fell in many areas.”

Trend unfolds

Several Beck’s field agronomists stationed around the Midwest saw a similar trend. There were variations, with extreme flooding in northwest Iowa and Nebraska in late May and into June. Soybeans planted in mid- to late May looked good through July. However, earlier-planted soybeans tended to have the advantage when rain clouds disappeared around mid-August.

“Many of us count on ‘county fair rains’ in July,” Gauck explains. “Fortunately, rains came to most areas and set us up for what we thought would be a great fall.

“However, as we moved through August, many areas stopped receiving significant rainfall. For many, it remained dry through most of September, too. If you applied fungicides earlier, they helped hold on to yield potential and control diseases resulting from July rains. Soybean pod counts remained high.

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“But the dry spell took some soybean size away. Individual seed size suffered more than in areas that received at least some rain. Rain is critical for seed size, and seed size is a key component for high yield.”

Dry weather timing

The 2024 season also emphasized that usually, dry weather later during the reproductive period threatens high yield potential in soybeans much quicker than extended dry weather earlier in the season.

“Many areas were dry in June, even if it was wet in May,” Gauck recalls. “However, soybeans tend to compensate better for dry weather then than later in the season.

“In the Soybean Watch ’24 field, soybeans were somewhat shorter than normal by the end of June compared to years when moisture was plentiful. When we examined plants, though, we found nodes were closer together than normal, too. Soybean plants were stacking nodes, and more nodes mean more opportunities for pods. We felt soybeans were still in good shape for a run at high yields.”

So, where did those high yields go for mid-May-planted soybeans, like the Soybean Watch ’24 field? The irrigated field yielded less than 70 bushels per acre, with dry corners only yielding 50 bushels per acre.

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“This field had water, but water isn’t the whole answer by itself,” Gauck explains. “For fields that didn’t have irrigation, lack of moisture late definitely explains late pod abortion and smaller seed size, which in turn explains lower yield.”

In the Soybean Watch ’24 field, Gauck notes that soybeans on one soil type, an eroded clay loam, didn’t fare as well. “Lack of height held them back,” he says. “We will follow up to see if soybean cyst nematode or low soil fertility levels might have also been factors.”