Trouble brewing inside corn bins


As spring nears and weather warms, concern is rising about 2009 corn stored in bins. Much of the crop came out of the field at lower-than-normal quality and higher moisture.

Charles Hurburgh, grain quality specialist heading the Iowa Grain Quality Initiative at Iowa State University, offers the following information on managing stored corn. He says the properties of the corn causing the most concern are:

• It was wet, with more than 20% moisture, some much greater.

• It was light. Test weights averaged about 52 pounds per bushel with little increase after drying. Light corn spoils faster and breaks more in handling.

• It had low protein, less than 7.5% at 15% moisture.

Storage life is an issue. This corn has about half of the shelf life of normal corn with the same moisture and temperature. There was also more damage by mold in the field, about 3% to 5%, where normal is 1% to 2%. The field mold was mainly cladiosporium, which doesn’t produce toxins. There was some incidence of other molds and toxins in either hail-damaged corn or very late planted corn. Toxins won’t go away in storage, but usually don’t increase either.

Grain should be uniformly cool at 35 degrees F or below. The active period for grain spoilage begins in late February, as outdoor air temperatures rise.

Key Points

• Managing 2009 corn stored in bins is very important now as weather warms.

• Check bins weekly from now on; shelf life of 2009 corn is shorter than normal.

• Record grain temperature weekly; higher temperature may indicate spoilage.

Check corn weekly now

You should be checking stored corn weekly from now on, as 2009 corn has a much shorter storage time or shelf life than normal. Record the grain temperature on every inspection — more often if you have an electronic system that monitors continuously. Increases in the temperature over time when there has been no fan activity are an indication of spoilage starting. Grain is a good insulator, so a slow rise in a temperature monitor could mean a much greater problem some distance from the sensor.

Once corn has started to spoil, problems will return even after aeration cooling; the shelf life has been used and this corn will create problems until moved out of storage.

Corn can be kept cold, even frozen, further into spring as long as the corn is clean; it has had the center core removed to take out fines and trash; and the bin has fans in the peak to bring in fresh air to control condensation dripping.

Things to do or check now, before problems show up:

• Know the moisture, test weight and temperature of the grain in every bin. These are the key parameters that determine future condition.

• If you have corn at 20% or higher moisture, move or dry it immediately.

• Market by test weight, lightest corn first.

• In February or March, remove some corn from each bin if possible. Check it and re-level the grain in the bin.

• If there is an increase in grain temperature, act immediately.

• Corn for feed should be tested for toxins (vomitoxin) and protein.

• Test for toxins by drawing at least 5 pounds; grind the whole sample for the test. Composites of several individual loads or undivided bin samples are best.

Not all stored corn is in good condition. Outdoor storage of corn has had problems; some firms used it as temporary wet holding space with poor results. Bins have been emptied with corn in poor condition. This means there will be marketing concerns the entire year.

The average damage level of 2009 corn was high out of the field, leaving little room to blend off storage problems. You need a lot of good corn to blend off the damaged corn and there isn’t a lot of good corn available.

Since 65% of Iowa corn is used for ethanol, which has low tolerances for damage and damage-related toxins, you can expect damage discounts to increase, and that corn will be graded more carefully. On the other hand, corn that is kept in good condition into summer will be in demand. However, you should expect that even the dry corn will start to have issues in late summer.

For more information, visit the archive of articles at www.iowagrain.org.

Source: ISU Extension

This article published in the March, 2010 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2010.