Corn cobs can be composted but since the core is usually pretty tough when the ears reach maturity (sweet corn cob as opposed to baby corn stage), they’ll probably take quite a while to rot down – chop them up to speed up the process but they’re still not going to be the fastest. (Some people get around this sort of problem by keeping two types of compost heap – one for things that will rot quickly, and one for things that will rot slowly. The first will provide regular compost for the garden, the second will produce it eventually too but the main purpose is to keep the first pile clutter-free – and keep other stuff out of landfill of course.)
Apparently they can be shredded and used as fibre in cattle fodder, burned into charcoal and on a large scale, can be used to make a industrial chemical compound.
