Bunker (Horizontal) Silo Forage Capacity

The forage a horizontal bunker or trench silo holds: the trapezoidal cross-section (bottom + top)/2 x average settled depth, times length, times as-fed density, over 2,000 lb/ton. A 30 ft wide, 8 ft deep, 100 ft bunker at 44 lb/ft^3 holds about 528 tons. Enter equal bottom and top widths for vertical walls, a wider top for sloped. As-fed density is an input (corn silage ~40-50 lb/ft^3); use the settled depth. A core or weigh-back governs the real inventory.

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Formula and source

cross_section = (bottom_width + top_width)/2 x average_depth; volume = cross_section x length; tons = volume x density / 2000.

Horizontal (bunker/trench) silo sizing per NRCS / MWPS (Midwest Plan Service) forage storage references, by name; trapezoidal-prism geometry.

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