Agricultural silos work by creating a pressurized area within a cylindrical container that helps to keep fodder and hay that is used to feed farm animals free from spoilage. There are several different types of silos that vary slightly in design but operate in the same manner to keep animal food from rotting. Most silos exist as upright cylinders that are constructed with sturdy materials such as porcelain or steel that help to prevent corrosion.
In addition to steel and porcelain, some silos are made from other metals, masonry and wooden components. Silos of all varieties contain a closed top as well as a sealed bottom. Their bases are typically sealed with organic matter, such as dirt or soil, and may also be closed with canvas, paper or plastic. Having an enclosed bottom prevents air from entering silos, which expedites the process of food spoilage. In addition to keeping food safe, the bottoms of silos are typically removable from the rest of the unit, which allows the materials within to be unloaded from the bottom portion. Food is removed from silos using farm machines called unloaders and must be removed within a certain period of time to keep the contents of the silo fresh.