Bunkers & Trenches
At first glance, a bunker silo looks like a cheaper option for storing feed. This is a common method used in some European Countries and is “familiar” to some farmers who have immigrated to the Americas. We all tend to stick with what we are familiar with at ANY cost. Bunker silos, in the long run, is a very expensive way to store feed. In addition, Bunkers are not immune to the problems that occur in every silage program regardless of the size of the operation. Consider the following:
1) Safety Issues for bunker silos and drive-over piles.
a) Roll-over possibilities when packing
b) A straight “drop off” a concrete retaining wall.
c) Tip hazard by carrying the bucket too high when unloading bunker.
d) Getting run over by machinery when filling or unloading
e) Slippery plastic can cause a “fall from height” hazard.
f) Crushed by an avalanche/collapsing silage.
2) High “forage in” versus “silage out” losses in bunker silos, drive-over piles, and bags.
a) Requires close, time consuming management to reduce Feed Loss.
b) Requires “excessive” lactic acid bacterial inoculant.
c) Requires “Uniform” density of at least 15 lbs of DM per ft or 44 lbs of fresh weight per ft.
d) Requires an “expensive” protective “Seal” via Double polyethylene sheets (Environmental issues?) or use an Oxygen limiting barrier film.
3) Large variation in the DM content and/or nutritional quality of the ensiled forage.
a) Solution is to Use “Multiple” bunker silos to improve forage inventory control.
4) Excessive surface-spoiled silage in sealed bunker silos and drive-over piles.
a) Requires excessive and time consuming “Management” to prevent surface spoilage.
b) Prevent surface cover (Plastic Sheets) from getting damaged.
This is just the “short list” of things to consider with a bunker silo. For more detailed information see attached report from Penn State University Dairy Nutrition Workshop; updated June, 2010 which is STILL timely information.