Fodder is consumed by monsters in the barn.One monster requires one unit of fodder per day.Fodder can be bought from Erik, or harvested manually with a sickle with each square granting a single unit of fodder or harvested by a monster with each square providing multiple units of fodder (based either on friendship or prosperity). A method of easily achieving prosperity in the Homestead is by planting lots of fodder and not cutting it, each unit of fully grown fodder spawns a random Runey every day. Once you achieve prosperity in at least one area, you can cut the fodder once every day and it will grow back the next day, giving you a daily supply of fodder and Runeys.