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Harvesting Corn Silage at Optimal Moisture Levels


Getting into fields at the proper time to chop silage is often challenging, regardless of year and weather conditions. This year (2022) particularly, prolonged dry periods have put some producers in a tough spot regarding silage harvest. With the help of Extension Educators across the state, we will monitor moisture levels of various hybrids as producers ready for silage harvest. Measurements for the week of August 23 are reported in the table below:

Table 1: Current corn moisture levels

As individual hybrids dry down, silage moisture should be monitored to insure optimal moisture content during harvest. To learn more about how to calculate your own moisture sample using a microwave oven, check out this video from Penn State Extension. Silage moisture levels can also be assessed with digital forage moisture testers. Stay tuned to Field Crop News for weekly updates on these hybrids as they continue to dry down.


Remember, optimal moisture content for silage harvest varies slightly based on the structure used for storage. For maximum corn silage quality, use the following as a guide:


Table 2: Optimal silage moisture levels


What effect does dry weather have on corn silage harvest?

If not monitored closely, corn can 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, leading to improper fermentation, molding, and heating of the forage – all of which reduce quality.


Though drought conditions are often considered to be negative for crop production, they can have some interesting effects on corn silage. For example, moisture-deprived corn often has high crude protein levels, high fiber digestibility, and net energy content typically doesn’t suffer too badly. Though high nitrate concentrations may be cause for concern in heavily fertilized fields, this can be reliably checked with a forage nitrate test. Safe nitrate levels for animal forages can be found online.


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

  • Decreasing length of cut and creating a finer particle helps to promote better packing and increases the digestibility of the kernel. However, when the particle size is smaller due to a finer chop, rations should be modified to ensure adequate digestive fiber.

  • Water can be uniformly added to dry silage to increase moisture content to aid in proper fermentation. When adding water to silage, the fill rate of most silos should be slowed due to slow water flows from most garden hoses and to ensure uniform water distribution.

  • Liquid inoculant additives such as propionic acid and Lactobacillus buchneri can be used to promote aerobic stability and decrease mold growth. These inoculants should be added at concentrations based on the manufacturer’s instructions.

  • Kernel processing helps to pack silage more densely, which can lead to better stability of aerobic organisms, thereby aiding proper fermentation. This also boosts forage quality by increasing starch digestibility of the kernel, which could be a problem in dry silage.

September 2, 2022


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