Corn silage harvest coming soon, timing assistance available

Corn silage harvest season is a relatively stressful time for livestock farms, and can be for non-farm neighbors, as well, due to increased farm equipment traffic on the roadways. Although a bit extra stress, silage harvest season is critically important to the economic viability of our area’s livestock industry.

On a per-acre basis, corn silage is our area’s most valuable field crop. Harvest timing of this high volume, high value crop is dependent on the whole-plant moisture of the standing corn. However, there is significant date variability from year to year when the moisture is correct, and not every farm harvests at the same whole-plant moisture.

In general terms, corn is ready for proper ensilage when the whole-plant moisture measures somewhere around 65%. This occurs approximately 50 to 55 days after the corn tassels, although soil moisture can change that up to 1 week. In 2020, the earliest area corn started tasseling around July 15, with most fields tasseling between July 19 and 25. The type of storage structure which a farm utilizes to ensile their corn silage will also change the optimum harvest dates, with horizontal silos requiring moister corn and vertical silos requiring drier corn.

2020 tasseling dates likely mean that most acres of corn silage in our area will be harvested in the first two weeks of September, but some acres will be later. The Marinette office of UW-Madison Division of Extension is offering livestock producers an opportunity to help monitor whole-plant moisture with three sample testing dates: Sept. 1, Sept. 8 and Sept. 15.

Each of these dates will have four sampling sites: Middle Inlet Town Hall from 10:30 to 11:15 a.m.; Crivitz Feed Mill from 11:30 a.m. to 12:15 p.m.; Beaver Town Hall from 12:30 to 1:30 p.m.; and Grover Town Hall from 1:45 to 2:45 p.m. Full details can be found in the agriculture newsletter or online under the agriculture tab at marinette.extension.wisc.edu.

It is critical that livestock farms make proper harvest timing decisions, as corn which is too dry may not ensile properly and corn that is too wet is unlikely to be at optimum feeding value and can actually seep out the most nutritive portion of the silage. The economic value of an acre of corn silage is dictated by the combination of yield and feeding value. Yield is dictated by corn hybrid planted, growing conditions, and height of harvest. Feeding value is dictated by starch content, fiber digestibility and proper ensiling.

In our two counties, an acre of corn silage will yield approximately 16-20 fresh tons/acre. Each fresh ton of corn silage’s value to a farm is based on how much meat or milk it can help a farm produce. Proper ensiling can change this value up or down $100 per acre very easily, illustrating easily why decision-making based on good data is important.

It is simpler to look at corn silage sale value according to current year corn grain price and fertilizer prices. A fresh ton has about 8 bushels of grain equivalency (at $3.10 per bushel, about $25) and this year has a fertilizer replacement (for the non-grain portion) value of around $10 to $12. The combination of these two factors yields a per fresh ton value of $35 to $37. 18 tons times $36 per ton equals a per acre value of $650.

Although this sales value doesn’t change as much as the on-farm feeding value, proper harvest timing does still play a part. Harvesting too early (too wet) will decrease the amount of grain equivalency, whereas harvesting too late (too dry) decreases yield measured at the farm level. Both of these can reduce sales value 10% very easily, or up to $65 per acre in lost value.

Any producers wanting to discuss corn silage management in more detail or any other horticultural or agricultural questions can contact Scott Reuss, Marinette and Oconto County agriculture and horticulture agent, at 715-732-7510 or scott.reuss@wisc.edu.