Effects of residue types and plastic mulch on earthworm aporrectodea trapezoides (Duges, 1828) within mesocosms at a salt-affected soil

Earthworm colonization is an effective management practice to improve soil conditions. In a salt-affected reclamation soil, we conducted a mesocosm experiment to test the effects of organic residue application (no organic residues, clover residues or sheep manure) and plastic film (mulching or no mulching) on the survival, biomass and production of earthworms (Aporrectodea trapezoides (Duges, 1828)). Results showed that application of organic residues yielded a higher survival rate (37-100%) and biomass (0.43-0.98 g) of earthworms than the treatments without organic residue, regardless of plastic mulch. Moreover, the application of sheep manure significantly increased earthworm survival (58%) and biomass (160%) compared to the application of clover residues, which may be due to high soil available resources and nutrients in the soils with sheep manure. No significant differences (p = 0.26) in the survival rate (37-100% and 47-82%) or biomass of A. trapezoides were observed between the mulch and no-mulch treatments. This study indicated that animal manure out-performed clover residues in promoting the growth and survival of A. trapezoides in a reclaimed, salt-affected soil. Moreover, plastic film mulching improved soil moisture, but had no effect on the survival and biomass of A. trapezoides.