Decomposers play a vital role in the ecosystem as they breakdown the organic components of dead and decaying matter into simpler substances. The organic matter is recycled in the ecosystem thus acting as cleansing agent for the environment. Also, they return back the mineral elements into the soil to be re-used by plants for growth which helps in maintaining the fertility of soil.

Nitrifying bacteria break down ammonia in soil to nitrates which act as fertilizer to the soil. The ammonia in soil comes from decomposition of dead plants and animals.