Slow-maturing crops could still be bin-busters despite cool temps
All summer long, a lack of heat units has been in the back of a lot of Corn Belt farmers' minds. It's kept crop progress chronically tardy this summer and now, with the forecast calling for temperatures cooling as low as the 40s in some areas, what was in the back of farmers' minds is now front and center.
But, even though corn and soybean progress is behind pace, crop conditions are, right now, on track for record yields. Will they reach fruition before frost's nip?
It's been "cool but not too cold" in the western and central Corn Belt, says Iowa State University Extension plant pathologist Rich Pope. Mid-August saw another dropoff of growing degree days (GDD), but it wasn't completely to the corn and soybean crops' detriment.
"During the week of August 17, we lost a net 50 to 60 degree days to average, but favorable night temperatures allowed for crop conditions to improve slightly," Pope says. "Another 2 or 3 weeks of good weather and we will begin the final drydown push to harvest."
In the past 17 years, the GDD range for Iowa has ranged from a surplus of more than 200 in 2007 (a year that ended up with "mostly average" yield and quality for the state's corn and soybean crops) to a deficit of almost 400 GDD in 1992, a year with which Pope says 2009 has a lot in common so far.
"May 1992 was a bit above normal, but that was the end of that. Once June came, week by week found us falling more and more behind in degree day accumulations," he says. "We did receive ample rain in July and August, but the cold slowed crop development considerably."
While he notes that it's still "too early to call," ISU Extension climatologist Elwynn Taylor said earlier this summer that the 1992 parallel bides well for this year's crops if the killing frost can be pushed back to an average or later time.
"The weather this season has a lot in common with 1992 and 2004 across the U.S. Both summers were warm on the west coast and cold in the Corn Belt," Taylor said last month. "Both had record high corn yields in the Midwest. 2009, even with the shaky start, is set up to have a record high yield...Too early to call this a forecast, but it is worth watching."
But, if this year continues to mirror 1992, temperatures may remain on the lower side of average, but frost may come later, Pope adds. Still, it might spawn other grain quality issues down the road. "Frost came to central Iowa late in September, and although both corn and soybean crop yields were quite good, slow or inhibited dry down and resultant grain quality issues were a considerable and costly," he says.
So, what's it look like? Charlie Notis of Freese-Notis Weather, Inc., in Des Moines, Iowa, says cool temperatures will remain the dominant weather feature for much of the Corn Belt for about the next week. But, so far, it will stay "cool" and not reach frost levels just yet.
"The big story for the weekend and early next week still looks to be cool temperatures. For Saturday through Monday, I would still expect that most locations in the Corn Belt will see at least one day (but in some cases two or even three days) with highs below 70 degrees (with some places in Wisconsin and Michigan not getting above 60)," Notis says. "I would look for most of the region to see lows in the 40s, but we could see a few of the normally colder locations in northern Iowa, Minnesota, and Wisconsin dip into the upper 30s. It is not a frost situation, but certainly one that will keep crop maturation rates quite slow. We should see a return to more seasonable readings by next Wednesday."