A reader asked a question about why, when all farm buildings have been removed on what used to be a dairy farm, the tower silos remain. The answer depends in part on what the silo is made of. Most silos built in the past 50 years were made of poured concrete or concrete staves.
We had four concrete stave silos on the Miner Institute that we wanted removed so we could build a shed to store sawdust. We called a company that sells concrete stave silos and they agreed to purchase the two that were the brand they sell. They also agreed to take down the other two silos for free, keeping the galvanized steel fittings and silo unloaders and leaving the staves for us to deal with. They did just as promised, breaking very few of the 70-lb staves in the process. We were told that the two silos they kept were going to be erected right away on another farm. But although over 20 years old, our silos were in good condition; putting wet forage into a concrete stave silo results in acids eating away the concrete, so some concrete stave silos aren't worth "recycling" even if the owner is willing to give them away.
Poured concrete silos are as close to a permanent structure as can be imagined: they're so massive that they can't be moved, and the concrete walls are much thicker than a silo stave. Set into a poured concrete foundation, these silos are really difficult-almost impossible-to tip over without endangering life and limb. So, these silos sit unattended and unused for decades after farming operations have ceased, a highly visible reminder of the past.
I would expect that some poured concrete silos may be sitting there 100 years from now, looking much like they do today.
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