A good burning barrel needs holes near the bottom to supply air.  A pick axe or a geology hammer works well for putting in the holes.  Put most of them between 6 and 12 inches from the base.

Used for burning trash on a weekly basis a barrel lasts for years.  If you store it where it is dry, it will last longer, as the alternation of heat and wet causes it to rust faster.

Leave a few inches of ashes in it when emptying.  This protects the bottom from the heat of the coals.