corn field

Climate Smart Farming Growing Degree Day Calculator tool that can help farmers plan for this falls corn silage harvest.

Corn Silage Maturity

This is the time of year we typically start thinking about corn silking/tasseling and the time from silking to silage harvest.

Obviously there is not much (if any) corn silking right now but here a few thoughts in the topic. One bit of good news is that the temperature projections for August, September and October show a reasonable probability of above average temperatures.

temperature projections for August, September and October

An old rule of thumb is 6-7 weeks but this should not be relied on, especially this year.

  1. We have better methods today.
  2. This rule of thumb assumes the crop will be progressing through this stage in July, August, early September. That will not be the case this year and GDD accumulation per day (or week) in late September or October will be slower increasing the likelihood it will take longer.

Recording silking/tasseling date and tracking Growing Degree Day accumulation is a useful indicator.

Earlier this year we talked about a new tool from Climate Smart Farming, the Growing Degree Day Calculator tool that can be used to look at expected GDD accumulation from planting, based on long term averages.

Direction video from Kitty O’Neil:

Projecting GDD accumulation from silking date is another good application of this tool.

By putting in the silking/tasseling date as your start date you can look at the projected date for silage harvest based on work by Bill Cox showing 750-800 GDD’s between silking and silage harvest.

Growing Degree Days (86/50) from Silking to Silage Harvest

*Study by Bill Cox at Aurora Research Farm

Relative Maturity GDD’s (Silking to 32% Whole Plant DM)

96-100 750

101-115 800

We can extrapolate that <96 day RM corn will likely take 750 GDD or slightly less

Whole Plant DM for Silage Harvest

Keep in mind that this work on GDD’s needed from silking to silage harvest was based on the corn plant getting to 32% DM so this should be used as an early indicator for harvest since we would really like to see whole plant DM at harvest closer to 35%.

While the rate of dry down obviously varies with weather conditions, a rule of thumb is 0.5 to 0.75% per day but some days the rate can be zero. Anyway, we could expect the crop to reach 35% DM 4 to 6 days after we hit the GDD benchmarks listed here.

Last updated May 18, 2020