This week has been a wet one for Iowa, and Iowa State University grain quality specialist Charlie Hurburgh has issued a caution for farmers getting ready to harvest 2018 corn and soybean crops.
Even in southern Iowa, where it was dry this summer, fields are receiving moisture now — too much, in some cases. It may not be the best situation for farmers who will need to harvest their corn earlier and wetter than they intended. “They’ll have to dry the grain in the bin instead of letting it stand in the field to dry on the stalk. Once a corn plant forms the black layer in the kernel tips, that indicates maturity. In these wet field situations, farmers need to get the corn out of the field once it reaches maturity — before ear mold starts to become a big problem,” says Hurburgh.
Harvest at higher grain moisture
It costs more to artificially dry grain, compared to letting Mother Nature dry it in the field. But drying it in your grain drying system on-farm or having it custom-dried at the local elevator will protect the corn while it’s in storage. “The worst-case scenario,” says Hurburgh, “is if we have continued rain in September.”
The Midwest is currently getting a strong flow of moisture from the Gulf of Mexico, notes ISU Extension climatologist Elwynn Taylor. “The Gulf has always provided 85% of the moisture that falls in Iowa annually,” he says. “Most of Iowa’s rainfall originates from the Gulf of Mexico. The other 15% might be locally started rain from our own sources or something coming into Iowa from the Great Lakes, for example. But for the most part, it’s the Gulf of Mexico that brings our rainfall, and our index is showing how strong the flow is — well-above normal. And it looks like it’s going to stay that way for a while.”
More moisture from Gulf of Mexico
What’s causing the Gulf of Mexico to pump all this moisture up to the central U.S.? A strong Bermuda high-pressure system, says Taylor. It’s as strong as it normally gets in that area. From the circulation of air around that high-pressure system, air is coming up from the Gulf, carrying moist air into the Midwest.
“With that source of moisture, the probability of having above-normal precipitation this fall is very significant,” he says.
Are we moving toward an El Niño?
An El Niño weather pattern is considered good for Iowa and the Midwest; it keeps the Corn Belt closer to normal weather — good for crops. “This current El Niño has started, and those of us who study El Niño weather patterns believe this coming winter the El Niño will have sufficient strength to keep the winter weather closer to average, rather than have an extreme winter for cold and snow,” says Taylor.
“Meanwhile, the effects of this developing El Niño are not strongly with us, and the effect of the Bermuda high pressure is with us,” he adds. “Other effects that are with us are tropical storms. It’s tropical storm season, and the forecast says there’s a chance of a tropical depression coming ashore in the Gulf of Mexico and coming to the Corn Belt. That always brings a load of moisture beyond normal when it happens. It’s looking like the probability of that occurring is real at this time.”
Too much moisture causing problems
Taylor hasn’t heard any reports yet of Noah’s Ark landing in Iowa, but with the large amount of rain in recent weeks, Noah may not be too far away. Rainfall totals in some areas in Iowa are being measured in feet for the past couple months, instead of inches.
“In Iowa when we get that much rain — a foot of moisture — that’s a lot,” says Taylor. “In Iowa 30 years ago, it wasn’t uncommon to have someplace in the state with a foot to 15 inches of rainfall in a 48-hour period. But that didn’t happen for the last 15 or so years. Now we are in a place in the weather cycle where that much rainfall can happen — and will likely occur more often in Iowa over the next five or six years.”
If moisture from a single storm system gets to around a foot of rain, “we’ve got real problems,” says Taylor. “Not just muddy fields, but flooded fields.”
Current concerns, farmers with wet fields
What are Taylor’s concerns as things stand now? What should Iowa farmers be watching out for this fall?
“The current weather pattern we are in will tend to be on the wet side of normal,” he says. “And if you’ve got a crop that’s ready to harvest and you are questioning whether to do it this week or next, do it.”
Some farmers will say, “My field is a little bit muddy.” Deciding whether to go ahead and harvest is each farmer’s decision, says Taylor. “But be sure to check the next 10-day outlook from National Weather Service. Those are just outlooks; they’re not really forecasts. But they can give you a clue as to what would be your best decision.”
Several years since Iowa has had wet fall
Taylor says it’s been a long time since Iowa has gone into fall as wet as it looks like most of the state is heading into in the 2018 harvest season. “We’re not used to having the fall precipitation at a peak — although it’s not an unheard-of occurrence,” he notes. “Right now, it kind of looks that way, because of the positions of the very high and low pressures, and bringing in the moisture up from the Gulf of Mexico.”
He adds, “Remember, moisture from the Gulf of Mexico is not extraordinary, because its where 85% of our moisture in Iowa comes from. Nevertheless, it’s a little stronger than normal this time, as the airflow in early September is stronger than normal. It looks like this weather pattern will persist for the next few weeks.”