Role of the earthworm, Eisenia foetida, in affecting organic matter decomposition in microcosms of sludge-amended soil.

(1) Organic matter decomposition was monitored for 49 days at 15 0C by measuring CO2 fluxes from microcosms in the form of soil cores. Some microcosms were amended with activated sewage sludge and/or Eisenia foetida (Oligochaeta). The biomass of E. foetida increased only when sludge was added. (2) The redox potential (Eh > 390 mV) indicated oxidizing conditions and no methane was produced. Those microcosms amended with sludge had an exponential decline in carbon mineralization without E. foetida. Decreased rates of sludge decomposition were arrested by E.foetida. (3) Labile constituents of sludge were converted to earthworm biomass and respiration. The increase in biomass accelerated sludge stabilization which reduces odours and pathogens. (4) Earthworm activity dispersed the sludge within the soil.