How earthworm density affects microbial biomas and activity in pig manure

We studied the influence of the earthworm, Eisenia fetida, on the microbial populations during the vermicomposting of pig manure. Fresh pig manure was placed in replicated boxes with (two densities, 25 and 50) and without earthworms for a period of 16 d. Samples were destructively collected periodically and analyzed for microbial biomass nitrogen, microbial respiration, substrate-induced respiration (SIR) and substrate dehydrogenase activity. Microbial biomass N, microbial respiration, SIR and substrate dehydrogenase activity were significantly lower in the earthworm treatments after 8 d.