2011-11-25 / Farm News

Extension Specialist: Damaged Corn Crop Requires Proper Harvest, Drying, Storage

Purdue Report
by Jennifer Stewart

The hot, dry summer took its toll on some of Indiana’s corn crop, and corn that was planted later than normal is being harvested at higher moistures. According to a Purdue Extension grain storage and drying specialist, that means growers need to pay extra attention to harvest methods, drying and grain storage.

In some portions of the state, corn is more susceptible to lodging than usual, and there have been a few reports of poor kernel fill and small kernels, said Matt Roberts. Other producers 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 said. “The presence of broken kernels, stalks and cobs in a grain bin can restrict airflow. Even with stateof the-art grain spreaders, broken kernels and foreign material tend to accumulate in the center of bins.”

He said that 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 said. “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 said.

Beyond causing airflow problems, broken and damaged kernels facilitate mold and insect growth, he said. 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,” said 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.”

He pointed out that in one study, the percentage of severely cracked kernels increased from 10 percent at two percentage points per hour moisture removal to 35 percent at seven 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 said. 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

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