Commercial compost activators contain microorganisms that help start and maintain the decomposition process in a compost pile. These products are costly and usually unnecessary, advises "Fine Gardening" magazine. Instead, introduce microorganisms into your compost heap with a simple homemade solution of soil and manure. Compost activators are less important to the composting process than the compost materials themselves. Strive for a balance of 15 parts carbon material to 1 part nitrogen. Keep the pile moist and turn it often to speed up the decomposition process.
Layer your compost pile, starting with a layer of 6 to 8 inches of carbon materials, such as shredded newspaper, straw or wood chips. Follow that layer with 2 to 4 inches of nitrogen materials, including food scraps, grass clippings and plant debris.
Sprinkle each nitrogen layer with 1/2 inch of garden soil and 1/2 inch of manure. Garden soil and manure both contain microorganisms---bacteria that accelerates the decomposition process. Manure also adds nitrogen to the pile. Water each layer using a garden hose.
Continue layering your compost pile. Aim for a pile that is at least 3 feet high. Top the pile with the remaining garden soil and manure, and wet the pile thoroughly using a garden hose. The pile should feel about as moist as a wrung-out sponge.
If the pile does not heating up, add more nitrogen-rich ingredients, such as grass clippings or leaves. If the pile has an unpleasant odour, add more carbon material in the form of straw, wood chips, shredded newspapers or dead leaves. Use bone or blood meal as nitrogen-rich compost activators if desired. Manure and soil are usually sufficient.