How Drought Impacts Next Year's Yields

How Drought Impacts Next Year's Yields

Poor soil moisture will keep next year's yields "at or below trend"

Nearing the end of another successful Farm Progress Show in Iowa last week, I made my way to the Pioneer Hi-Bred tent to hear Iowa State meteorologist Elwynn Taylor talk about… the weather.

Yes, weather. And drought, as depressing as it is. Because no one makes weather sound more interesting than Elwynn Taylor.

If you've never heard Taylor talk, check his speaking schedule. He's a truly remarkable guy – one of the few meteorologists who understands farming, teaches agronomy and climatology, and can actually make atmospheric pressure sound, well, exciting.

Next to fearless Ag economist Barry Flinchbaugh over at K-State, Taylor is one of Ag's greatest human assets.

Iowa State meteorologist Elwynn Taylor says depleted subsoil moisture will make it tough on 2013 yields.

I heard Taylor a few years ago talk about how the Corn Belt was "due" for a drought. And as you might expect, now people are all over him, asking if we can expect a repeat performance next year. His answer? No one knows. But he did draw some parallels to 1988. Like 1988, this drought can be traced to the tropical Pacific Ocean, where a periodic cooling of sea surface temperatures — a phenomenon known as La Niña — helped reconfigure global weather patterns during the past two years.

"It's the second strongest la Niña weather cycle, which means a lot more variable weather – and we got the same effect this year as we did in 1988 and in the mid-50s, the year of the strongest la Nina," he says.

Trend…lower

Trend corn yields this year were supposed to be around 160 bu. per acre, but most yield reports are coming in around 120 bu. per acre - or lower. "After six years of above trend yields in the Corn Belt we dipped in 2010 and it may be four years in a row with lower trend yields," he says. "La Niña did all that. I wouldn't be shocked to death if La Niña came back, but we don't have any scientific data to predict that right now."

Taylor's gift is his ability to break things down to simple terms. He told the Farm Progress crowd it takes 20 inches of timely precipitation, including 10 or more inches of rain from April to harvest, to get near trend corn yields; It takes 25 inches to make record high yields. "It might take 40 inches to get rivers back to normal levels," he adds. "Usually it's 10 inches to make the tiles run – but that's in average years."

Some farmers may be looking at planting decisions based on dry soils. But Taylor says both corn and soybeans need the same amount of moisture to make trend yields – albeit corn needs more in July and beans need more in August. "There's no reason to think you should go all in on one crop because of weather fears," he says. "Ideal yields require the same amount of moisture."

His bottom line? Don't expect to get back to trend yields next year, not with the scorcher we've been through. Most Corn Belt soils now need 18 inches of water to sink into the ground from October to next June, just to get back to normal subsurface moisture levels.

"If we're going to replenish this moisture between those dates and not cause erosion and problems in planting, it would be amazing," he says. "A record high yield becomes very rare in this current scenario. Even to get up to trend line yield is shaky.

"My outlook for next year is, not as harsh as this year in terms of weather, and not significantly above trend yield, if at all," he says. "We should expect a fourth year of U.S. corn yields at or below trend yield."

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