While some Illinois corn growers are heading into harvest early, others are telling Ken Ferrie their corn is drying slowly in the field – they’re seeing moisture levels drop only one point per week.
The rule of thumb historically is that mature corn that dies after reaching black layer will dry in the field at a rate of 0.5% to 1.0% per day in September, and then 0.25% to 0.5% per day in October, according to Iowa State University Extension.
Generally, it takes about 30 GDDs to lower grain moisture each point from 30% down to 25%. Drying from 25% to 20% percent requires about 45 GDDs per point of moisture, according to Peter Thomison, Ohio State University retired Extension state specialist for corn production.
But many agronomic factors come into play that influence dry down, including genetics, delayed planting, nutrient use, weather conditions — especially temperature, humidity, and rainfall — and disease issues.
Reaching Black Layer Prematurely Plays A Role
One reason for a slow drydown process in some fields is a result of the crop dying prematurely.
Premature corn death occurred in parts of the Midwest crop and for multiple reasons. In dry and droughty areas of Illinois, farmers saw high heat kill their corn crop prior to black layer. Likewise, Ferrie says many Iowa and Minnesota growers had corn that died before black layer due to southern rust and other disease pressure – even where the crop had adequate water.
“Corn that dies before black layer from dry weather, high heat or disease pressure can dry down slower,” says Ferrie, Farm Journal Field Agronomist, in this week’s Boots In The Field podcast.
The damage caused by adverse weather or disease can cause the plants to reach physiological maturity (black layer) prematurely, leading to poor dry-down and higher grain moisture, according to Purdue University corn specialists in an online article.
“When it comes to corn that dies pre black layer, you are at the mercy of God’s corn dryer,” says Ferrie, who encourages farmers to keep checking corn moisture levels and stalk quality to determine when to start harvest.
He offers three additional recommendations:
1. Don’t forget to calibrate combine yield monitors. “We need good, calibrated maps for when we analyze this crop at your yield map meetings this winter,” Ferrie says. “What these maps will teach us is invaluable in helping us shape our plans going forward, especially for you guys that are on the high-res program.”
2. Stay on top of harvest losses. Dry crops will mean more header loss for both corn and beans. “The tip pullback we’re seeing in [central Illinois] corn means we’re going to have to work a little harder to get this stuff off the cob. So keep a close eye on your thrashing losses,” he says.
3. Be proactive with your soybean harvest. “If they’re testing but cutting tough, keep grinding them out at that higher moisture. Don’t let that get away from you,” Ferrie says. “If you can knock beans out of the pod and they’re testing, even though that combine’s groaning, keep going as these moistures drop.”
Ferrie gives an update on yields he’s seeing across Illinois in this week’s Boots In The Field podcast here:
