Application of earthworms on soil remediation in southern china

Abstract

A key soil invertebrate, earthworms significantly affect soil quality and the broader ecosystem. In this paper, we review the ecological characteristics of earthworm species Amynthas corticis, A. morrisi, A. robustus, A. aspergillum, Pontoscolex corethrurus and Eisenia fetida in southern China and their effects on soil pH, enzyme activity, metal accumulation and availability, the formation of soil pores and micro-aggregates, and the decomposition of organic waste. In sum: (1) Earthworms in southern China can survive in soil with a wide range of pH (3.8-7.9), and their survival rates are related to soil type, organic matter content, soil contamination level and earthworm species; (2) Enzyme activity in earthworm guts, castings and drilosphere indicate the appetite of different earthworm species, the process of soil nutrient cycling and soil microbial characteristics, respectively; (3) Earthworms are capable of accumulating different metals and altering their availability, but this capability varies depending on earthworm species, element and soil type; (4) Earthworm activity and cast production can change soil structure, increase the amount of soil pores and affect the size, amount and distribution of soil aggregates. Moreover, we highlight the potential application of earthworms toward resolving the acidification of red soil, nutrient imbalance in tea gardens, soil metal contamination, the compaction and destruction of soil during expressway construction, and the utilization of agricultural and urban organic waste. At present, due to insufficient investigations into the physiological characteristics of earthworms and a lack of Amynthas sp. breeding technology, earthworm applications are scarcely conducted at medium and large scales. Hence the promotion of earthworm technology is especially limited in southern China. It will be necessary to explore the potential of earthworms in soil restoration further and to analyze the mechanisms earthworms employ during soil construction and management in order to develop technologies to perform the functions currently occupied by earthworms.