Good packing procedures help minimize costly surface-spoiled silage in bunker silos and drive-over piles.
According to Keith Bolsen, a retired Kansas State University professor, who now operates a silage-management consulting business with his wife, Ruthie, a packing density of 13 to 15 pounds of dry matter per cubic foot in the top 3 feet of silage is ideal for minimizing surface spoilage.
Also be sure to shape all surfaces so water drains off the bunker or pile, and do not exceed a 3-to-1 slope on the back, front, and side slopes.
Bolsen has provided 10 steps to minimize or prevent surface-spoiled silage in bunker silos and drive-over piles:
- Achieve a packing density of 13 to 15 pounds of dry matter per cubic foot in the top 3 feet of silage.
- Shape all surfaces so water drains off the bunker or pile, and do not exceed a 3-to-1 slope on the back, front, and side slopes. Seal the forage surface immediately after filling.
- Two sheets of plastic or a sheet of oxygen-barrier film are preferred to a single sheet of plastic.
- Overlap the sheets that cover the forage surface by a minimum of 4 to 6 feet.
- Arrange plastic sheets so runoff water does not come into contact with silage.
- Sheets should reach 6 feet off the forage surface around the perimeter of a drive-over pile.
- Put uniform weight on the sheets over the entire surface of a bunker or pile, and double the weight placed on the overlapping sheets. Bias-ply truck sidewall disks, with or without a lacework of holes, are the most common alternative to full-casing tires. Sandbags, filled with pea gravel, are an effective way to anchor the overlapping sheets, and sandbags provide a heavy, uniform weight at the interface of the sheets and bunker silo wall. Sidewall disks and sandbags can be stacked, and if placed on pallets, they can be moved easily and lifted to the top of a bunker wall when the silo is being sealed and lifted to the top of the feedout face when the cover is removed. A 6- to 12-inch layer of sand/soil or sandbags is an effective way to anchor sheets around the perimeter of piles.
- Prevent damage to the sheet or film during the entire storage period. Mow the area surrounding a bunker or pile and put up temporary fencing as safe guards against domesticated and wild animals.
- Regular inspection and repair is recommended because extensive spoilage can develop quickly if air and water penetrate the silage mass.
- Full-casing discarded tires used to anchor polyethylene sheets were the standard for many years. These tires are cumbersome to handle and messy. Also, standing water in full-casing tires can help spread the West Nile virus, which is another reason to avoid using full-casing tires.
For more advice on covering bunker silos and drive-over silage piles, read Shield forage quality in the May 2012 issue of Dairy Herd Management.
Source: Keith and Ruthie Bolsen