Barrel composters are containers in which compostable scraps and material can be placed to go through the composting process. Soil is combined with these materials, as is water and heat, to allow the scraps of food or organic material to break down and release nutrients. This compost material can then be used for gardening or other planting to enrich the soil and promote faster and more efficient plant growth. Barrel composters are often able to rotate so the materials within can be mixed regularly. The barrel will be mounted on a stand that allows such rotation.
The specific design of barrel composters can vary significantly, and it is not exceptionally difficult to build such units from scratch. Store bought units are often made from plastic to prevent moisture from escaping and to keep the soil dark and cool. Barrel composters will have an opening, either at the top of the barrel or on the barrel's side, to allow organic material to be placed within at any time. Moisture is a key component of composting, and the opening will allow a person to add water to the mix every so often. The opening usually features a hatch door that can be secured closed during rotation and composting periods.
The plastic barrel is mounted on a frame, either plastic or metal in most cases, that allows for a pivot system. The pivot system will allow barrel composters to rotate, either by using a built-in hand crank, or simply by turning the barrel by hand. The stand will also allow for a more stable platform when accessing the contents of the barrel. The frame will need to be quite sturdy, as the weight of the barrel when full with compostable matter can get quite heavy.
Making barrel composters from scratch is not difficult. A frame can be built quickly and easily from wood, and the barrel can either be purchased and then mounted to the frame, or it can be salvaged from another use and mounted. The barrel will need to be cleaned thoroughly, and barrels that previously housed caustic chemicals or other materials that can be harmful should be avoided. Metal barrels can be used as well, though it will be necessary to line the barrel with plastic or some other impermeable material to prevent the metal or any rust that may develop within the barrel from coming in contact with the soil.