Corn Silage Dry Down Update: Week of September 2

 

Corn silage harvest is in full swing in the southern portion of Pennsylvania, and where dry conditions persist in other regions, silage corn is continuing to draw closer to the optimum moisture content for harvest. If not monitored closely, the corn could go from ideal moisture to too dry, increasing the risk of storage losses. Silage harvested below the optimal moisture content can be difficult to pack and lead to a failure in excluding air to ensure proper fermentation, resulting in molding and heating of the forage, and in turn reducing quality.

 

According to the Penn State Agronomy Guide, corn silage should be harvested when whole plant moisture reaches 55 to 68%. For conventional upright silos, optimum moisture should be 63 to 68%; bunker silos – 65 to 68%; oxygen-limiting silos – 55 to 60%; and ag bags – 63 to 68% moisture.

 

Knowing the average expected dry down rate per day for corn silage is 0.5 to 0.6% will help to aid in determining proper harvest timing when moisture becomes close to optimal; however, the dry down rate varies by hybrid, and dry weather conditions further quickens the loss of moisture and could cause 0.7-0.9% dry down on a daily basis. Although not perfectly accurate, a quick field test for estimating corn moisture levels can be done by breaking an ear in half and looking closely at the bottom half of the tip of the kernels. When the separation, or “milk line”, is ¼ of the way down the kernel, moisture is approximately 70%. As the milk line reaches to approximately ½ of the way down the kernel, the moisture is approximately 65%. For a more accurate measurement of whole plant moisture, take a few plants at dent stage and run them through a chopper or lawn mower, allowing for all the plant parts to be thoroughly mixed together. Then use a Koster tester or a microwave to determine plant moisture by first weighing the wet sample, then slowly heating while continually stopping and stirring until the sample is completely dry. The difference in the weights of the wet and dry sample will indicate the moisture level of the silage. For more detailed instructions on using the microwave to determine moisture content, visit Determining Forage Moisture Content with a Microwave Oven .

 

In the case of chopping silage that has become drier than the optimal moisture according to your storage facility , there are some management recommendations that can aid in ensuring proper fermentation and quality of your forage.

To get an estimation of current field conditions around the state, extension educators around the state continue dry down sampling. This chart illustrates dry-down testing and growing degree day accumulations for this week’s sampling effort.

 

 

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