In areas where corn is being harvested at higher moisture levels than usual farmers must pay careful attention, says Matt Roberts, a Purdue Extension grain storage and drying specialist. In some portions of Ohio and Indiana, corn is more susceptible to lodging than usual, and there have been a few reports of poor kernel fill and small kernels, says. Others report more cobs and stalk pieces or more fine material in their harvested corn.
"Low test weight corn can be more susceptible to kernel breakage during harvesting and handling than high test weight corn, and quite often more fine material is produced when corn is harvested at higher moistures," Roberts says. "The presence of broken kernels, stalks and cobs in a grain bin can restrict airflow. Even with state-of-the-art grain spreaders, broken kernels and foreign material tend to accumulate in the center of bins."
Ideally, grain should be cooled to 50 degrees or cooler to control insects and mold growth. If grain in the center of the bin isn't cooled thoroughly, mold and insects can grow there and eventually spread to other parts of the bin.
Bins need to be cored after they are filled to remove the accumulation of broken kernels and foreign material.
"Coring can be accomplished by removing several loads of grain from the bin," Roberts says. "It also will help to level the top of the grain mass. Air finds the path of least resistance and the coring and leveling should eliminate or reduce the higher airflow resistance in the center of the bin. Therefore, the bin will be aerated more evenly."
One way to help reduce broken kernels, cobs and stalks is for growers to make sure their combines are adjusted regularly as crop conditions change. Screening equipment should be used to remove as many of the broken kernels and as much of the plant material as possible from the grain before it goes into storage.
"Even if great care is taken to properly set combines and clean the grain, bins still should be cored in order to ensure even airflow," Roberts says.
Beyond just causing airflow problems, he said broken and damaged kernels play host to mold and insect growth. Because low test weight kernels can be further damaged when dried, producers should pay close attention to drying technique.
"Managers using high-temperature dryers need to be especially careful since these systems are particularly hard on kernels," says Richard Stroshine, Purdue agricultural and biological engineering professor and grain drying specialist. "If kernel temperatures get too high during high-temperature drying and there is rapid moisture removal followed by rapid cooling, the severity of kernel stress cracking will increase and this will increase the likelihood of breakage during subsequent handling."
In one study, the percentage of severely cracked kernels increased from 10% at 2 percentage points per hour moisture removal to 35% at 7 points per hour removal rate.
Ideally, kernel temperature in high-temperature dryers shouldn't exceed 140 degrees and samples should be taken throughout the day to monitor for stress cracking, Stroshine says. Lowering the drying air temperature, in-bin dryeration or multiple pass drying can reduce both kernel stress cracking and handling breakage.
More information about proper harvest, drying and storage techniques can be found on Purdue Extension's Post Harvest Grain Quality website at http://www.grainquality.org