COLUMBUS – Despite relatively cool conditions recently, much of the early planted corn in southwestern Ohio and parts of west central Ohio is rapidly maturing.
Corn growers planning to ensile corn should be monitoring corn fields closely because their corn may be near or at the optimal stage for silage harvest, according to Ohio State corn specialist Peter Thomison.
When to chop. Determining the proper time to harvest corn for silage is critical because whole plant dry matter content varies with maturity and it influences fermentation.
Ensiling corn silage that is too wet produces poor fermentation, seepage losses, and lowered animal intake. Ensiling excessively dry corn increases the risk of heat damage and molding.
Depends on storage. Thomison said corn silage preserved between 30 percent and 40 percent dry matter generally provides good fermentation and animal performance, but different storage structures require different dry matter concentrations for optimal fermentation.
Table 1 shows the recommended target dry matter content for corn silage in different types of structures.
The recommended dry matter content for upright, bottom unloading silos is higher to ensure easier unloading. Horizontal silos require a lower dry matter content (higher moisture content) to ensure adequate packing to eliminate oxygen and prevent heating.
Milkline not accurate. Observing the development of the corn kernel milkline has been suggested as an easy way to estimate when corn is at the proper dry matter content for ensiling.
Generally, recommendations have been to harvest corn for silage when the milkline is one-half to two-thirds of the way down the kernel. However, Ohio research has indicated that there is a lot of variability in the relationship between the kernel milkline and whole plant dry matter content. The milkline is not a very accurate or reliable guide to gauge whole plant dry matter content, Thomison said.
Hybrid, planting date, and growing season can affect the relationship between kernel milkline position and whole plant dry matter content. However, the appearance of the milkline in the upper quarter of the kernel indicates that the crop is very near the optimal time to harvest.
A sample should be taken at this time and dry matter content determined with a commercial forage moisture tester or microwave oven.
Using a commercial forage moisture tester or microwave oven to determine the dry matter content is the best way to accurately determine the optimal time to harvest corn silage according to the storage structure to be used.
Thomison said waiting until black layer will almost always result in corn being too dry for proper packing and fermentation, especially in horizontal and upright, top unloading silos.
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Table 1.
Recommended Dry Matter Content
for Corn Silage Stored in Different Structures
Structure %DM
Upright, Top Unloading 30-40
Upright, Bottom Unloading 40-45
Horizontal 30-35
