How far will my corn dry down?

  • Oct 14
    Chuck Belanger
    How far will my corn dry down? By Chuck Belanger on October 14, 2014
    Categories: Grain Corn

    Corn grain dry down has been a hot topic.  We have been spoiled the past few years with exceptional corn dry down and are not accustomed to waiting for moistures to get below the 30% mark.  In most of the province, the biggest worry is that corn will not make physical maturity (black layer) before our first killing frost.  In some areas, they already have had a killing frost and more to come in the next week or two.  Below are two scenarios to consider, corn at physical maturity and corn that has not reached maturity.

    Dry Down Potential for Corn at Physical Maturity
    According to research being done at Purdue University in Indiana, corn is usually at approximately 30% moisture at physical maturity (black layer).  From that point on we need to accumulate 30 Growing Degree Days (GDDs) for every point of moisture decrease.  To lose 0.5% moisture, we need to accumulate 15 GDDs and to lose 0.75% moisture, we need to accumulate 22 GDDs.

    According to these numbers, for our corn to get down to 25% moisture we would need to accumulate 150 GDDs from the time of black layer.  The ten year average for accumulated GDDs for the month of October is 228.4 GDDs.  If we look at the three coldest Octobers over the past 10 years, the average is 185.3 GDDs.

    This being said, if we had reached physical maturity by October 1st, then the chances of getting our corn below 25% moisture is good, however, as of October 1st, not a lot of crop had reached that stage yet.

    Dry Down Potential for corn not reaching Physical Maturity before a killing frost
    A good portion of Ontario’s corn crop experienced a killing frost in September.  This frost occurred before corn reached maturity.  According to University of Wisconsin research, corn that was frosted prior to maturity can have 2 – 6% points higher than the normal drying rate of matured corn prior to a frost, which may result in a few days delay in dry down rate. 

    Other Plant Characteristics affecting Grain Dry Down
    There are many physical characteristics that effect dry down.  Thickness and number of husk leaves can affect drying.  Thinner and fewer will allow faster dry down.  Ear tip exposure can also affect dry down.  If it is exposed, it could dry down quicker, but could also open the ear to moulds if rain continues.  A loose husk will dry down quicker than a tight husk.  The angle of the ear also could affect dry down. Ears that droop tend to dry down more quickly than those that are upright. 

    As you can see, there are a lot of factors that affect dry down - not only temperature, but physical plant characteristics as well.  It is very hard to determine where your moisture will be at a certain point.  You need to know the progress of your crop to determine this and you need the weather to co-operate.  Hopefully, I have given you some information to help you determine your dry down potential.  If you need more information, feel free to contact any of your Maizex representatives.

    Chuck Belanger, Maizex Seeds Yield Specialist, North Essex and South Chatham-Kent Counties
    Twitter: @sprayman63