When packing this year’s silage corn in bunker silos or piles, aim for densities of at least 15 lbs of dry matter per cubic foot, advises Phil Kaatz, Michigan State University Extension forage educator.

“Getting adequate density on the silage will prevent air infiltration and reduce dry matter losses,” he says.

Silage packed at 15 lbs/cu ft had lost 15.9% of its dry matter after six months, according to Cornell University research. Losses in silage packed at 10 lbs/cu ft were 20.2% in that timeframe, but just 10% in silage packed to 22 lbs/cu ft.

“A general guideline for the amount of packing equipment needed to match up with high harvesting 

rates is to have 800 lbs of packing weight per ton of silage delivered,” Kaatz says. “For a 50-ton/hour harvest rate, a producer would need 50 x 800 = 40,000 lbs, or 20 tons of packing equipment, to achieve high density levels. It becomes very easy for harvesting equipment to overwhelm packing capacity at the bunker.”

Some producers have put wetter silage on the top of the silo to increase packing densities, but Kaatz says that’s not a good idea. The best fermentation occurs in the range of 30-40% dry matter, and leachate may be a problem if the crop is harvested too wet.

Brian Holmes, University of Wisconsin ag engineer, found that the factors affecting silage density levels include:

  • Delivery rate – make sure the rate is matched to packing time.
  • Dry matter content – not too wet or dry.
  • Depth of silage in the bunker silo – lower portions of the silo are higher in density.
  • Packing tractor weight – more is better.
  • Packing layer thickness – consider 6” vs. 12”.
  • Packing time – match it to the delivery rate.

Of those factors, the Cornell researchers found that tractor weight and packing time were the most important factors affecting density, Kaatz reports.