It’s time to get ready for corn silage harvest

Two important considerations are silage density and processing corn silage.

During corn silage harvest it’s important for producers to pay special attention to the packing of their corn silage in a bunker silo. Getting adequate density on the silage will prevent air infiltration and reduce dry matter losses. For optimum storage and minimum dry matter loss, the standard producers should aim for is a silage density of 15 lbs. DM/ft3. Table 1 shows the loss differences for several silage densities.

Table 1. Dry matter loss as influenced by silage density – Ruppel (1992)

Density (lbs DM/ft3)

DM Loss, 180 days (%)













A general guideline for the amount of packing equipment needed to match up with high harvesting rates is to have 800 pounds of packing weight per ton of silage delivered. For 50 tons/hour harvest rate a producer would need 50 x 800 = 40,000 pounds 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. Fermentation of the silage occurs best in the range of 30 to 40 percent dry matter. Take into consideration the problems with leachate if harvesting silage that is too wet. Increasing dry matter content beyond 40 percent to improve density is counterproductive for good fermentation.

Brian Holmes, ag engineer at the University of Wisconsin-Madison has studied what factors affect silage density levels. The following factors all influenced silage dry matter density in the bunker silo:

  • Delivery rate - making sure the rate is matched to packing time
  • Dry matter content - not too wet nor too dry
  • Depth of silage in the bunker silo – lower portions of the silo are higher in density
  • Increased tractor weight – more is better
  • Reducing the packing layer thickness – consider 6 inches versus 12 inches
  • Packing time – matched to delivery rate

Of these factors, Ruppel et al. (1995) found that tractor weight and packing time were the most important factors affecting density.

Corn silage processing

In recent years, corn processing has become a more common practice. Whether you process in the field or at the silo, the advantages include:

  • Faster rate of silage fermentation
  • More densely packed material in the silo
  • Decreased dry matter loss in silage storage
  • Increased effectiveness of inoculants

Research at the USDA Dairy Forage Research Center supports that mechanical processing can improve feed efficiency and milk production in dairy cows. However, the equipment is expensive and may not pay for itself in a smaller operation. Larger farms are able to capitalize on new technology because of the volume handled and size of their enterprise. Small operations need to look at custom operators for efficiency and eliminate the high cost of purchasing large equipment.

A study by Randy Shaver from the University of Wisconsin studied the effects of corn processing and chop length of corn silage and the effects on intake, digestion and milk production for dairy cows. He found that processing of corn silage will give improved dry matter intake, starch digestion, lactation performance and results also showed less sorting and cob refusal in the feed bunk for TMR containing processed corn silage.

In his study, he found that the effect of length of particle sizes of 0.95 cm verses 1.90 cm were minimal for animal performance in processed corn silage. However, longer chop length did prevent depression of fiber digestion observed at the shorter length while still achieving improved starch digestibility with processing.

In conclusion, pay attention when delivering corn silage to the bunker silo so you don’t overload the packing process. Also, when considering whether to process your corn silage or not, make sure to count the cost of this management practice before committing to a large equipment purchase.

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