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What is a Grain Silo?

A grain silo is a towering structure designed for storing bulk grains safely and efficiently. Its purpose is to protect the grain from the elements and pests, ensuring a stable food supply. By maintaining the quality of the harvest, silos play a crucial role in global agriculture. Wondering how these agricultural giants have evolved over time? Join us as we explore their history and importance.
C. Ausbrooks
C. Ausbrooks

A grain silo is a structure created to store materials in bulk. They are usually tall and cylindrical, but can also be constructed in the form of warehouses, domes, or large elongated bags. They primarily hold grain, seed, or silage, fodder that is harvested green and then stored and left to ferment. This fodder is then used to feed livestock or as a biofuel, and is usually grass, alfalfa, sorghum, oats, or maize.

The three primary types of grain silos are bag silos, bunker silos, and tower silos. Bag silos are an inexpensive way to store grain and silage, and they are made out of a heavy, durable plastic, usually 6 to 8 feet (2 to 2.5 meters) in diameter, and can be of any length. They are often used for overflows, when more storage space for grain is necessary.

A group of four small bag silos that hold grain.
A group of four small bag silos that hold grain.

To access the grain, farmers simply tear through the plastic, using any sharp object. Each section of the bag is cut open, until all the grain has been removed and used as needed. Some farmers use this method exclusively, due to its ease of access, low maintenance requirements, and inexpensive price.

Bunker silos are similar to bag silos in that they both store grain and silage, and are made primarily of heavy-duty plastic. These silos are created by digging a pit in the ground and filling it with grain until it forms a large mound. A large plastic tarp is then placed over the mound and covered by heavy objects, usually rocks, to prevent it from blowing off. Concrete walls are sometimes formed around it for protection. Bunker silos are inexpensive and require little upkeep.

Multiple tower silos.
Multiple tower silos.

Tower silos are the most common type of grain silo. These tall structures can be up to 275 feet (84 meters) high, and are typically made out of concrete. The tower silo uses gravity to pack and distribute the grain. The weight of the material pushes down, compressing the bottom layers, allowing more room for storage.

A recurring issue with tower silos is deterioration due to the storage of silage, which is highly acidic. Over time, it can begin to eat away at the walls of the structure. A high level of maintenance is required or the silo can collapse. Each time it is emptied, the farmer should do a thorough check of the entire structure to ensure that no damage is present.

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Discussion Comments


As far as using a concrete silo on its side, How are you going to lay it down without it breaking? I'd say that's almost impossible.

A metal silo on its side can be buried, but not deeply enough to act as a war bunker -- maybe a tornado shelter of some sort, but that's 40 feet underground at the low point, and unless its made of solid steel plates, it can't be buried deep enough to resist any bombs. The soil on top acts as the protection.

You're better off burying a silo straight up and down to you desired depth, cutting off the top and pouring a concrete roof and then burying it all 20 feet down. Good luck.


@malmal - You guessed it -- farmers tend to be traditionalists, with their farms often passed down from generation to generation, and they're very set in their ways about things like how to milk cows and where they store their grain. Trust me, I grew up on farms since my parents were both dairy milkers.

Grain silo construction, to my knowledge, hasn't changed much at all since people started using grain silos. They operate very simply using natural gravity, which means that there are less parts that can break, and for farmers that means less maintenance needed to store their grain in a silo.

One concern that tower type silos can give to farmers is that of mold. If the grain inside of a tower silo starts molding, conceivably the entire silo full of grain could be bad, and it's not safe to feed to the cows. Grain costs a lot when you buy it in bulk and load it into a silo, so the farmer really doesn't want this to happen.

Thankfully, the concrete and heavy construction of silos helps keep the grain dry and out of the sunlight inside, so mold is rarely a problem. The biggest threat for molding grain in silos is usually if the grain is wet or already starting to mold when it is loaded into the silo.


Are grain silos still in that much common use these days? When I think of them, I always imagine the typical scene of a steel grain silo painted red to match the barn like you see in old-fashioned farm scenes in paintings and storybook illustrations.

I don't live anywhere near actual farmland, though, so maybe I'm just out of the loop. It seems like grain silo building techniques would change over the years as technology got better, but maybe farms are one of those businesses where you don't change how you do things if it works?


@ahain - Thanks for the feedback!

I'm planning on filling the bottom quarter or maybe third of the silo (when on its side) with cement to make a flat spot as the floor. The walls will curve outward, but I figure I could work with that and make shelves that hang on the curved spots without taking up space in the middle of the room.

You have a good point that solid cement walls of a grain silo ought to be just as effective as hollow-centered cement in cinder block form. Even one layer of cinder blocks is proven to block out nuclear radiation, so a grain silo with walls that thick would be awesome.

This is all kind of a dream project of mine. I'm working on saving up enough to actually make it. I wonder how much used grain silos cost?


@Malka - I'll assume you're talking about a tower silo, judging by the description of "turning it on its side". I don't know about a metal tower silo, but a concrete tower silo seems like it would indeed be a very sturdy set of walls for a survival house of sorts.

I'd imagine the concrete walls of a tower grain silo would be comparable to concrete cinder blocks in terms of strength, especially since cinder blocks tend to be hollow in the middle. A concrete silo might actually be tougher!

If you're aiming to make a survival bunker that's pretty big, I think looking for a used grain silo for sale is a creative idea. My only concern if it was me would be, if I turned the tower on its side to make it into a building, how would I deal with the floor being a rounded shape like the ceiling was?


This may sound unorthodox, but has anybody here ever considered using a metal grain silo as the basic outline shape for an underground bunker or survival housing? I'd imagine if you turned it on its side, a grain silo would be pretty sturdy for this, and could be buried to make a rounded shape underground for people to live in.

Do you think the walls would be tough enough to protect anybody? Maybe I should go for a more traditional rectangular structure using cinder blocks to build the basic walls instead.


If you drive through the state of Illinois, you will see a lot of farm country. Some of these farms still have old grain silos on them that have not been used for many years. Many of the silos that are not currently being used, look like they are in pretty bad shape, as no maintenance has been done on them.

Some farmers still use small grain silos on their farms, but most of them will have there grain stored in larger silos at a local elevator. I know that you must keep watch to make sure that the grain in the silo does not go bad. It would not be a good thing to be ready to use the grain and realize that it has spoiled while being stored in the silo.


Living my whole life in the Midwest in farm country, I am very familiar with grain silos. The small town I grew up in had an elevator with several grain storage bins for farmers. The grain silos are helpful for the farmers who need the space to store large amounts of grain from the harvest.

Fall was always an especially busy time for the elevator when the silos were being filled with newly harvested grain. I still remember the sounds and distinct smells that came from the elevator in town.

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    • A group of four small bag silos that hold grain.
      By: Erik Schumann
      A group of four small bag silos that hold grain.
    • Multiple tower silos.
      By: Tootles
      Multiple tower silos.
    • Pile of sorghum grain.
      By: j3rn3j
      Pile of sorghum grain.
    • Barley, a type of grain.
      By: 1999istek
      Barley, a type of grain.
    • Whole oats.
      By: Popova Olga
      Whole oats.
    • Oats are a type of cereal grass.
      By: Liaurinko
      Oats are a type of cereal grass.