Thus, a trade-off exists between moisture and yield.
For corn silage frosted prior to the dent stage, the moisture content will be too high for successful ensiling. The silage crop should be allowed to dry in the field for several days and moisture content should be monitored. For corn frosted during the dent stage, the harvest should begin quickly to prevent yield loss as damaged leaves are shed or break off the plant. Because mold can occur on the ears before the corn reaches the desired moisture level, producers may have to begin harvesting immediately.
To help control problems with excess moisture, mix wet silage with ground grain, straw or chopped hay. The rule of thumb is to add about 30 pounds of dry material per ton of silage to reduce silage moisture 1 percentage unit.
The maturity may be uneven in many corn fields. When harve sting a corn field with differing maturity levels, handle field sections separately where possible. In fields where the chopper must move through areas differing in maturity, such as low spots, chop when the majority of the field is at the proper moisture.
The immature spots will be wetter than the rest of the field and moisture might seep in the silo, but as long as the seepage does not leave the silo, nothing is lost. Fermentation should be adequate to preserve the corn silage. However, corn that is too dry might develop a "hot spot" in which mold can develop, increasing the chances for mycotoxin development.
For many years, corn was harvested for silage at the black layer stage of development. However, more recent Wisconsin research recommends beginning corn silage harvesting at 50 percent kernel milk and finishing it by 25 percent kernel milk. Today, many hybrids grown have a "stay-green" trait that improves standability by keeping the stalk and leaves green while husk leaves turn brown and open, allowing the ear to dry.
If producers ensile frosted corn at the proper moisture content and follow other steps to provide good-quality silage, nitrate testing should not be necessary.
"The only way to know the actual composition of frosted corn silage is to have it tested by a good analysis lab," Schroeder says.
For more information on harvesting frost-damaged corn, visit http://www.ag.ndsu.edu/pubs/ansci/dairy/as1256.pdf.