[Effects of earthworm on soil microbes and biological fertility: A review].

Earthworms are considered as 'ecosystem engineers', as they affect soil microbial community and function by improving micro-habitat, increasing surface area of organic compound, feeding, and transporting microorganisms. Multi-scale cavities created through earthworm movements help improve soil porosity and aeration, thus supporting microbial growth and reproduction. Earthworms also break down complex organic compounds into microbe-accessible nutrients by means of feeding on, crushing, and mixing soil. This results in elevated mineralization and improvement of cycling of key soil nutrients including carbon, nitrogen, and phosphorus, overall enhancing the soil biological fertility.