Impacts of a polyethylene silage pile underlay plastic with or without enhanced oxygen barrier (EOB) characteristics on preservation of whole crop maize silage, as well as a short investigation of peripheral deterioration on exposed silage faces

• Thin inner plastic films with enhanced oxygen barrier (EOB) properties are recognized by some agencies as a mitigation of silage deterioration.
• In large maize silage piles, underlay film with or without EOB properties had no impact on silage fermentation through 6 mo post pile building.
• In another pile, silage deterioration to a 25.4 cm depth occurred behind the exposed silage face, but was not impacted underlay film.
• In another pile, surface spoilage occurred behind the exposed silage face, and moved into the pile at a similar rate as silage face removal.
• Results do not support use of a thin plastic underlay film with EOB properties versus one without.

Large silage piles, up to 15,000 t, common in some dairy areas, present challenges since their large surface area creates an enhanced potential for oxygen to penetrate the mass. Use of thin inner (i.e., between the silage and main plastic cover) plastic films with enhanced oxygen barrier (EOB) properties are recognized by some governmental agencies as a mitigation of silage deterioration even though underlay films are generally accepted to only potentially impact the outer 30–50 cm of the silage in a pile. In four large maize silage piles, underlay film with or without EOB properties had no impact on silage fermentation parameters indicative of spoilage in the outer 25.4 cm of the silage pile, or in the 25.4–50.8 cm depth below the surface of closed silage piles at ∼3 and at ∼6 months post pile building. In contrast, in a 5th pile, there was evidence of deterioration in the surface silage to a 25.4 cm depth immediately behind the exposed silage face, which was not impacted by type of underlay film. A final experiment in a 6th pile showed that surface spoilage occurred well behind the exposed silage face, and that it moved into the pile at a similar rate as silage was removed from the face. Results do not support use of a thin plastic underlay film with EOB properties, versus one without, since air ingress to the silage mass through the silage pile cover appeared minimally causative of silage deterioration, which was associated with the exposed face. Maize silage deterioration of exposed face silage would likely be minimized by increasing speed of exposed face movement, and/or use of weight lines directly behind the exposed face, as has been recommended by others.