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Soil Temperatures Rising Across Corn Belt

Planting is under way, but corn progress is well behind the five-year average across most of the country due to a late spring.

“There has been some concern about how cold the spring has been and how that might be a setback to the crops,” says Elwynn Taylor, Extension climatologist at Iowa State University. “I’ve seen some other seasons that started off cool, and they can go either way. It’s a little bit early to be deciding if it has caused damage to the production of the Midwest or not.”

For the first time this spring in many parts of the Corn Belt, soil temperatures are reaching into a range suitable for planting this week.

“We’ve gone from cooler-than-normal soil temperatures to near normal rather suddenly, just in the past couple of days,” explains Taylor. “The soil temperature at a 4-inch depth needs to be 50°F. or greater for corn to develop. And so we’re just reaching those temperatures now this last day or two. Previous to that it has been way too cold in most places.

“Soybeans are more sensitive than corn to these low temperatures," Taylor says. "Some years, when the temperatures have been marginal, near 50°F. at the 4-inch depth, or maybe a little below, the soybean doesn’t do well because the seeds will swell and diseases may get in to destroy the seedling. Whereas corn can endure being too cold to grow for a bit of time, and then as soon as it warms up, do well. So, we recommend strongly if the soil temperatures are marginal, plant corn as opposed to soybeans so that you have a better chance of vigorous initial growth.”

In a report published Tuesday, meteorologist Kyle Tapley of Radiant Solutions said increasing soil temperatures will come gradually over the next week. The northern Plains may struggle to reach and sustain that critical 50°F. temperature, particularly in North Dakota. Cold weather is expected to return to the area in the next week to 10 days.

“Dry weather across the heart of the Corn Belt through the end of the month will favor fieldwork and allow planting to make better progress, mainly across southern portions of the Corn Belt,” the report says.

“For the next 10 days, we do anticipate it will be on the warm side. That’s an encouraging thing,” Taylor agrees.

"Between now and the middle of next week or so it looks quite good as far as painting goes. Temperatures are going to be warming up as well, especially early next week. We're really going to see temperatures warm up quite nicely ahead of that system later next week. So planting should make some significant progress on between now and next week," says Donald Keeney of Radiant Solutions.

The Corn Belt may see precipitation to start off the month of May. "The next significant rain event will start in the northwestern Midwest late Monday into Tuesday of next week and then a spread southward into the central Plains and the rest of the Midwest and Delta by Thursday and Friday of next week," Keeney says.

Midwest 31-60 Day Outlook

The most recent outlook for the 2018 growing season published by Radiant Solutions says temperature expectations across the Midwest are trending slightly warmer than average over the next 31 to 60 days.

“Near-normal rains in the Midwest would favor corn and soybean growth,” says the report.

Slightly wetter than normal conditions are also expected for some key ag producing states over the next 60 days. The forecast shows more precipitation in the west-central and far southern Plains, southern Delta, and western Midwest. This would bring much-needed moisture to the Plains and improve soil moisture for winter wheat.

South America

Recently dryness has been increasing across the southern parts of Brazil’s safrinha Corn Belt, but temperatures have been near normal. Tapley says hotter weather is on the way. Temperatures as much as 8°F. above normal over the next two weeks could cause stress in the southern 30% to 40% of the crop.

Conditions are expected to be drier than normal over the next month in north-central Brazil. “Below-normal rainfall will likely continue across central and northern portions of the safrinha corn belt in Brazil, which will likely result in some ongoing stress and yield reductions,” says a weather report published by Don Keeney of Radiant Solutions.

However, far western parts of the South American corn belt are getting more rain, which will likely prove helpful for late corn growth.

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