Most grain is used for feeding, and the normal practice is to conserve it by drying it to less than 14% moisture at harvest and keeping it in open, roofed stores until use.
Another way is to store it in sealed air-tight silos. What happen under such conditions is that the grain quickly converts the oxygen in the silo to carbon dioxide (CO2) and alcohol - i.e. the grain "kills itself". The grain loses its germination ability, and there is no risk of vermins, as they cannot live in oxygen-free surroundings. The process preserves and ferments the grain.