Pedosphere 31(3): 433--439, 2021
ISSN 1002-0160/CN 32-1315/P
©2021 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Earthworm biomass and population structure are negatively associated with changes in organic residue nitrogen concentration during vermicomposting
Bo ZHOU1, Yiyong CHEN1, Chi ZHANG2, Jianlong LI1, Hao TANG1, Jiayu LIU1, Jun DAI2, Jinchi TANG1
1Tea Research Institute, Guangdong Academy of Agricultural Sciences/Guangdong Provincial Key Laboratory of Tea Plant Resources Innovation and Utilization, Guangzhou 510640 (China)
2College of Natural Resources and Environment, South China Agricultural University/Key Laboratory of the Ministry of Agriculture for South China Farmland Conservation, Guangzhou 510642 (China)
ABSTRACT
      Vermicomposting is an efficient and environmentally friendly technology to dispose of agricultural organic residues. The efficiency of organic residue decomposition during vermicomposting is directly affected by the biomass and population structure of earthworms. In this study, we investigated how the earthworm biomass and population structure responded to changes in the physicochemical properties of six types of organic residue (cattle dung, herbal waste, rice straw, soybean straw, garden waste, and tea residues) during vermicomposting. Each type of organic residues was placed in a pot with earthworms Eisenia fetida, and the physicochemical properties of the organic residues and earthworm growth dynamics were recorded at 0, 30, 60, and 90 d of vermicomposting. The biomass and population structure of earthworms were stable or increased in rice straw, garden waste, and cattle dung within 60 d of vermicomposting, whereas in tea residues and herb waste, very little earthworm activity (3 adults and 2 cocoons) was recorded on day 30. Among the physicochemical parameters, the substrate C/N ratio was negatively correlated with earthworm growth dynamics. Decomposing organic residues showed higher NH4+-N and NH3--N concentrations but a lower total organic carbon content, which negatively affected earthworm growth and reproduction. We recommend that chemical properties of vermicomposting systems should be monitored regularly. At the threshold levels of decomposing organic residue NH4+-N and NH3--N concentrations, earthworms should be removed and the vermicompost can be harvested. Small- and large-scale farmers thus need to monitor the physicochemical properties of vermicompost to sustain active earthworm populations.
Key Words:  ammonium nitrogen,decomposing,earthworm biological traits,Eisenia fetida,nitrate nitrogen,organic residue dispose,physicochemical property
Citation: Zhou B, Chen Y Y, Zhang C, Li J L, Tang H, Liu J Y, Dai J, Tang J C. 2021. Earthworm biomass and population structure are negatively associated with changes in organic residue nitrogen concentration during vermicomposting. Pedosphere. 31(3): 433-439.
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