What Can We Learn From the Corn Forage Drydown During 1998?

Joe Lauer, Corn Agronomist

Before 1998 becomes too foggy in our memory, what lessons can we learn from the corn forage drydown during September 1998? In most years farmers would most often use the calendar, and typically would begin thinking about cutting corn forage around 15 Sep. Last year most farmers would have been ensiling corn that would probably have turned moldy in the silo because it would have been too dry. Corn drydown started earlier than normal. Fig. 1 describes corn forage drydown for 4 counties in Wisconsin. For a concrete stave silo, the optimum moisture to begin filling the silo is at 65% whole plant moisture. Last year the average date that these counties would be at 65% moisture was 9 Sep. Nearly a week earlier than normally expected.

Some summary points for determining when to harvest corn forage for ensiling:

1. Watch for kernel milkline movement in the cornfields you plan to ensile.

2. Use kernel milkline as a guide to begin checking forage moisture. For a bunker or bag silo, begin measuring forage moisture when kernels on ears are around 80% kernel milk; for concrete stave silos, begin measuring moisture when fields are around 60% kernel milk; and for oxygen limiting silos, begin monitoring moisture when fields are around 40% kernel milk. Usually about 95% of the time forage moisture will be too wet at these kernel stages, but you will know where that field is at for moisture.

3. Once the kernel milkline has begun to move and forage moisture is known, then use 0.5% per day forage drydown rate to predict the date you should recheck and/or chop the field to store at the proper moisture for the storage structure.