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Key silage storage management tips

Bill Ramsey Published on 01 July 2013

The U.S. Department of Agriculture estimated in 2012 that U.S. growers harvested 113,450,000 tons of corn as silage, with a conservative value of $7.3 billion.

The USDA also estimated that the dry matter (DM) loss in this corn silage was between 15 and 20 percent – for a staggering loss of $1.1 to $1.4 billion.

Dry matter losses not only deal a wallop to the wallet, but they also negatively affect the nutritional value of the remaining silage. That’s because shrink consumes the most valuable silage nutrients which must then be replaced with an equal energy source, such as corn grain.

In some beef and dairy operations, one person is responsible for growing, harvesting and storing the silage crop. But on many farms, these tasks are done on a contractual basis. Thus, effective planning, communication and coordination between livestock specialists becomes complex.

Sufficient moisture
The bacteria that create desirable fermentation need water to live, grow and produce acid. Sufficient moisture also enables the producer to expel the air in the silo more efficiently.

It is best to avoid harvesting corn silage when it is too wet. Plants should have sufficient maturity and strength to ensure an optimal nutritional value from each crop acre.

Mature plants are less likely to crush in the silo, so seepage is also less likely. Effluent – i.e., seepage fluid – is rich in sugars and readily digestible nutrients that can be lost with wet silage. Mixing wet silage with dry forage can help reduce fluid loss.

Optimal maturity
A premature corn silage harvest reduces DM yield per acre. Immature plants could deposit less dry matter and starch, resulting in an unforeseen economic loss.

Delay corn silage harvest to half-milk line or until plants exceed 30 percent DM for increased starch content and higher silage DM yields. Diets containing higher starch need less supplemental grain.

Often maturity and moisture are trade-offs. Forage sorghums, for example, contain an adequate level of nutrients at the early dough stage. However, to avoid seepage, harvest is usually delayed until the lower leaves start to turn brown.

Inoculate at the forage chopper
Silage inoculants can reduce DM loss in corn silage by 25 percent, or 2 to 5 percentage points.

DuPont Pioneer provides an inoculant value calculator (IVC) online at or in the Apple Store for iPad users. This tool calculates the economics of inoculating various forage crops and high-moisture corn to help determine the best product for the grower.

Reach an optimum silage density
Many beef and dairy producers are not achieving the recommended minimum silage DM density of 15 pounds per cubic foot. Producers should pack and cover silage to exclude air, which reduces fermentation loss.

Silage density and shrink loss are inversely related, so as packing density increases, shrink loss decreases. The goal should be to have a silage density of 15 to 16 pounds of DM and 44 to 48 pounds of fresh weight per cubic foot.

If producers increase density by 2 or 3 pounds of DM per cubic foot, that translates to a reduction in shrink loss of about 3 to 5 percentage points.

To improve density, several key considerations from Brian Holmes, University of Wisconsin – Madison, and Keith Bolsen, Kansas State University professor emeritus, include:

Check silage densities. But only do this if it can be done safely, and be prepared to adjust filling and packing procedures.

Reduce forage delivery rate. This is difficult to accomplish, as few producers and silage contractors are inclined to slow the harvest rate.

Employ well-trained, experienced people. Particularly those who operate the push-up or blade tractors. Provide training as needed and emphasize safety.

Increase rate of forage push-up and packing. By increasing this and the harvest rate, producers will reach the target density.

Spread forage consistently. Do this continually in thin layers of 6 to 8 inches during the entire filling and packing operation.

Increase packing tractor weight.

Increase the number of packing tractor passes over all forage layers. Caution: Additional tractor passes require more packing time per ton.

Increase packing passes near the walls. Consider this to increase density in that area of the silo.

Management steps to minimize or prevent surface-spoiled silage
• Shape all surfaces so water drains off the bunker or pile. The back, front and side slopes should not exceed a three-to-one slope. Seal forage surface immediately after filling is finished.

• Two sheets of plastic or a sheet of film are preferred to a single sheet of plastic.

• Overlap sheets that cover forage surface by a minimum of 4 to 6 feet.

• Arrange plastic sheets so runoff water does not come in 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; 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-inch 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 safeguards against domesticated and wild animals.

• Regular inspection and repair are recommended because extensive spoilage can develop quickly if air and water penetrate the silage mass.

• For many years, full-casing discarded tires were the standard tools used to anchor polyethylene sheets on bunkers and piles. However, these tires are cumbersome to handle and messy; in addition, standing water in full-casing tires can provide a breeding ground for mosquitoes that may carry the West Nile virus.

This season, producers using these silage storage tips should be able to retain better nutritional quality and minimize economic losses.  FG

References omitted due to space but are available upon request. Click here to email an editor.


Bill Ramsey

Western Livestock Information Manager
DuPont Pioneer