Much-needed precipitation through the U.S. heartland this year has replenished soil moisture, refilled ponds and promises to boost crop yields, thanks to the weather phenomenon known as El Niño, according to Iowa State University agricultural climatologist Elwynn Taylor. And the benefits for the Midwest may continue into 2016.
El Niño is associated with a warming of Pacific Ocean water, and tends to bring warmer, drier conditions to the northwest United States and cooler, wetter conditions to the Plains.
The conditions are a far cry from the recent La Niña – the opposite of El Niño, which brought drought to the central U.S., says Taylor.
"We've just come out of the second strongest La Niña in recorded history, about 200 years, and that brought us a disastrous drought. That's the drought we had in the Corn Belt in 2012. That's the first widespread drought that we've had in the Corn Belt since 1988."
He likened the El Niño-La Niña phenomenon to a pendulum that swings from one extreme direction for a 14-month period and then to the extreme in the opposite direction.
Because of the rainfall and mild temperatures in the central U.S., an El Niño gives a 70% chance of an above trend line yield for corn and soybeans in the Corn Belt, barring other factors. When corn yields are high in the Midwest, wheat yields in northwest states tend to be below average, because El Niño tends to bring drought to those states.
It's unclear how long the current El Niño will last, but in similar situations where one has followed a strong La Niña, the El Niño has lasted a full two years rather than 14 months, which is average.
"If it goes 14 months, then it gets us well into 2016. It could get us off to a good start with the crop, but it could go bad after that," Taylor says, noting that El Niño has sometimes gone on for 24 months – even 36 months on rare occasions.
"In ancient history, they've gone on for four or five years, but we don't expect to see that this time around," he adds.
El Niño tends to have closer to average conditions rather than extremes. The summer is not oppressively hot, the winter is not bitterly cold, and that is good news for people with winter wheat or cattle outside.
Scientists who study El Niño and La Niña have a good record for knowing four or five months in advance what conditions are coming. "That's good news, but it doesn't get you all the way through a growing season," he says.
Usually the change from La Niña to El Niño is gradual, taking months rather than weeks to occur. However, when a strong El Niño ends, it can suddenly go to a La Niña condition, such as the major drought we had in 1988 that began just weeks after the U.S. went into La Niña.
That's why risk management is so important. After El Niño, growers must be ready for yields and prices to change quickly.
Taylor says weather conditions through the 2020s may be much like the volatile years during the 1980s. And based on studies going back hundreds of years, the year 2025 bears watching.
"2025 isn't necessarily the year we expect a "Dust Bowl" to peak, but it would be typical," says Taylor. "The harshest years for weather for Midwest crops tend to be separated by 89 years. The worst year for the 1800s in Illinois and Iowa was 1847. Records were not kept that far back for Kansas and Nebraska. In the next century, the harshest weather year for crops was 1936. Tree rings indicate the 89-year tendency has existed for several centuries."
Taylor believes this means that weather will get increasingly volatile until we hit the extremes. "Remember, volatility goes both ways," he says. "Years with record-high yields, or yields with half of that, and that's a disaster. During the 18 years before 2010, we had consistent yields."
"This is an advantage the farmer has, to look at what is the year's volatility, what are the likely prices I can sell my grain at or buy my feed at this year, and what the likely low will be and the likely high," he continues. "You're not going to hit it exactly. Just realize this is likely to be a year that will have above trend line yields, and so we're going to have prices that go along with a higher yield. You don't know exactly how low they'll go, but as long as you're working on the correct side of the picture, you'll make a profit. It's hard to go bankrupt when you're making a profit."