Corn Silage Dry Down Update: Week of September 9, 2024

A weekly check-in on silage crop moisture progression at several locations across Pennsylvania.

Corn silage moisture content continues to be a critical component of harvesting a high-quality and high-yielding forage crop. Extension Educators across Pennsylvania are working with cooperating farms to harvest, chop, dry, and track moisture content of corn silage fields around the state.

Accumulated Growing Degree Days (GDD): A measure of the accumulated growing degree days counted at this location since planting. Calculated using 86/50-degree cutoffs.

Precipitation Deviation: A measure of this location’s departure from the 10-year precipitation average, calculated by subtracting rainfall from planting to current date from the 10-year average.

Growing Degree Day (GDD) Deviation: A measure of this location’s departure from the 10-year GDD average, calculated by subtracting GDD accumulation from planting to current date from the 10-year average.

Be sure to monitor field conditions and test moisture levels to determine the current moisture level of your corn crop. The average daily dry-down rate for silage is about 0.5% of moisture loss per day, with rates ranging from 0.0-1.0% in extreme weather conditions. In our observations, average daily dry-down rates ranged from 0.2% to 1.0% of moisture loss per day. All locations saw a notable decrease in dry-down rates in the past two weeks, as cooler weather has moved across the state and slowed the accumulation of growing degree days.

The past two weeks have seen both increased and decreased dry down rates from week to week, due largely in part to daytime temperature fluctuations. We have seen daily growing degree day accumulations ranging from 5 to 25 growing degree days per day, which will affect the daily rate of moisture loss. Continue monitoring field conditions, and be prepared to check moisture levels more often if weather conditions are forecasted for warm, sunny days. For an explanation of how growing degree days affects corn silage maturity progression, see Corn Silage Approaching Maturity – Moving Past Thumb Rules. To ensure your corn is harvested at the proper moisture level, we recommend chopping and drying samples each week to make sure your harvest is conducted in a timely manner.

For a comprehensive review of best management practices for harvesting, storing, and feeding silage, please see From Harvest to Feed: Understanding Silage Management