Microbial Dynamics of Endemic Earthworms on Soil Health and Sustainable Agriculture

Earthworms harness the microorganisms which are beneficial to the agro-ecosystem, as they synergistically decompose soil organic matter and help in nutrients cycling. Lampito mauritii and Perionyx excavatus are endemic earthworms which dominate the Indian soils, especially in south India. However, the exotic earthworm Eudrilus eugeniae has been harnessed for the formation of compost and organic matter decomposition. Endemic earthworms do not coexist with exotics as they eliminate the former due to competition for food and space. The present study aims to reveal the physical, chemical and biological differences between the different products of the endemic earthworms L. mauritii and P. excavatus and the exotic earthworm E. eugeniae to better understand their contributions to agricultural soil and nutrient management. The three major earthworm products include cast, compost and drilosphere soil of earthworms. Different groups of microorganisms present in earthworm products include major microbial groups, biofertilisers, carbon, and nitrogen mineralizers. The results reveal that the products of endemic earthworms show significant increase in biofertilisers such as nitrogen fixers and phosphate solubilizers, heterotrophic bacteria, fungi and actinomycetes compared to the products from the exotic earthworm. Among the three products studied, vermicompost, especially of the endemic species, shows a balanced C/ N ratio and increased microbial density including biofertilisers.