A Wet Spring Doesn’t Guarantee a Strong Finish

Missouri soybean fields entered summer with plenty of moisture, but experts say farmers shouldn’t mistake a wet spring for a guaranteed crop.

Missouri soybean farmers have already navigated a season full of weather extremes.

Record warmth, excessive rainfall, flooding and cooler temperatures have all made appearances during the first half of the growing season, forcing producers to adapt field by field and sometimes week by week.

“Producers have needed to plan around the weather this spring.”

Zack Leasor

Missouri State Climatologist and Assistant Professor, University of Missouri School of Natural Resources

February, March and April all ran warmer than average, and April became Missouri’s warmest on record. Those temperatures created early planting opportunities, but many producers couldn’t fully take advantage of them because fields remained too wet.

Statewide average precipitation during April reached 6.79 inches, nearly 3 inches above average.

Then conditions shifted again.

“After such a warm start to spring, May ended up being a cooler month, slowing down crop progress,” Leasor says. “Mid-May flooding also caused issues in many fields across central and northern Missouri.”

Conditions looked much different in the Bootheel.

“In the Bootheel, dry weather led to very early planting and timely rains have helped keep crop progress moving along so far,” he says.

The differing conditions underscore one of the biggest challenges facing Missouri soybean farmers. A statewide weather pattern rarely tells the whole story.

What Wet Conditions Can Mean Early in the Season

Excess moisture and cool temperatures can create problems for soybean establishment, but impacts vary considerably from field to field.

University of Missouri assistant professor of soybean farming systems Andre Reis says fields planted immediately before or during May’s cool, wet conditions faced the greatest risk.

“Prolonged soil saturation associated with cool temperatures may cause excess plant mortality, leading to replanting,” he says.

Those decisions can carry consequences later in the season.

Farmers may face a yield penalty from a later planting date if they choose to replant. Others may decide to keep a thinner stand rather than start over.

At the same time, not every field experienced problems.

“If the population is not severely affected, either because the crop was planted in early April and therefore avoided those conditions during germination and emergence, or because the area did not experience prolonged saturation despite the weather conditions, such as well-drained soil, then no yield impact is expected,” Reis says.

As summer arrives, however, experts say spring weather matters less than what happens next.

The Next 60 Days Will Matter Most

The biggest weather threats to soybean yield typically emerge during reproductive growth.

“During the yield-defining stages of pod setting and seed filling, the most common weather conditions historically associated with yield drag in Missouri are drought and extreme heat stress.”

Andre Reis

Assistant Professor of Soybean Farming Systems, University of Missouri

In much of Missouri, those critical stages occur between late June and late August.

Leasor says farmers should continue watching rainfall closely.

“We are heading into the longest days of the year with warm weather and high evapotranspiration rates, making continued timely rainfall critical,” he says.

Although forecasters are not currently predicting a major drought event, Leasor says recent years have demonstrated how quickly conditions can change.

Missouri has experienced multiple late-season flash drought events that developed after wet early-season conditions.

Soybeans Can Recover … Up to a Point

Soybeans have several built-in mechanisms that help them adapt to adversity.

“Soybean is a resilient crop because of its highly plastic growth strategy,” Reis says.

Plants can compensate for lower populations by adjusting their growth and producing additional leaf area or stem nodes. The crop also spreads risk across multiple flowering periods.

“Another mechanism is the occurrence of more than one flowering and pod-setting pulse, which spreads the risk of unfavorable weather conditions over a longer period,” Reis says.

Even so, resilience has limits.

“These strategies contribute to soybean resilience, but they are not foolproof against extended drought and heat during the yield-defining stages,” he says.

Weather Variability Is Becoming the New Normal

Leasor says Missouri farmers are managing a changing climate that brings both opportunities and challenges.

“Missouri is experiencing a trend in warmer temperatures during the spring and fall, generally lengthening the growing season,” he says.

At the same time, weather patterns continue to become more variable.

“The state’s climate is characterized by highly variable precipitation patterns, with frequent flood and drought events. Warmer temperatures are linked to more extreme precipitation and can also exacerbate drought conditions, leading to more variability and management challenges for farmers,” Leasor says.

Many weather conversations this summer will center around the emerging El Niño pattern, but Leasor says Missouri producers shouldn’t expect a clear signal.

“Unfortunately for Missouri, there’s not a strong relationship between El Niño and weather impacts during the warm season,” he says.

While Missouri has experienced both wet and dry summers during El Niño years, wetter summers are generally more common.

“Most of the U.S. is expecting a warmer than average summer, but we may see more moderate temperatures here in Missouri and the Midwest region if El Niño holds up in the forecast,” Leasor says.

Spring weather may set the stage, but late June through August often determines the final outcome.

For now, experts say farmers should stay focused on protecting yield during the weeks ahead. Spring weather may set the stage, but late June through August often determines the final outcome.