About Compost described the wonderfully complex food chain made up of the hundreds of different organisms found in a typical backyard compost pile. You may ask yourself where these creatures come from. For example, where are the thermophilic bacteria before the pile begins to heat up? All the organic materials in a compost pile already contain, on their surfaces, the various microorganisms needed for the decomposition process. Most of them are dormant and waiting until the environment is right before they become active.
Can you increase the number of organisms in the pile and by doing so increase the speed of decomposition? The answer is yes. Free sources of these microorganisms are readily available, or you can buy a compost activator. Commercial activators contain a combination of microbes as well as enzymes and other natural chemicals involved in the decay process.
However, the simplest way to ensure a generous supply of all the necessary bacteria, fungi, and other microorganisms is to throw a few handfuls of garden soil or old compost—each handful contains billions of microbes—on the pile as you build it. Make sure the pile contains sufficient air and moisture, since the microbes need the right environment to become active.
Most compost piles, especially passive ones, invariably attract invertebrate decomposers, such as earthworms, millipedes, and sowbugs. Even in a hot, actively managed pile, these organisms can be found decomposing material in the outer 12 inches of the pile, which usually remain cool. These creatures show up amazingly quickly, sometimes in just a week or two.
You don’t have to depend on nature to supply you with worms, among the most important decomposers in the pile. You can buy red wriggler fishing worms and add them to the pile. Or you can move earthworms from elsewhere in the yard to the pile. Another alternative is to get composting worms, which require the environment of a compost pile to survive. For more information on using worms in a compost pile, see Vermicomposting.
For thorough composting, each type of organism involved in the process must have access to the whole pile over time. The simplest way to accomplish this is to turn the compost pile periodically.