Substance which can be degraded and disposed off naturally by saprophytic organisms or decomposers are called biodegradable, e.g., organic remains, garbage, sen age, livestock waste. Substances which cannot be degraded by saprophytes are known as non-biodegradable. They are mostly man-made articles like pesticides, plastic, polyethylene etc. Biodegradable articles are formed naturally, in biosphere. Decomposer organisms feed on them by secreting digestive juices and absorbing the solubilised substances. Biogenetic nutrients are released in the process called mineralization.