Earthworms used as indicators of agricultural managements.

In order to assess the biological soil quality, it is necessary to develop some relevant bioindicators. Within all the biological indicators, earthworm should be used as bioindicators of agricultural practices. This study, realized in the Biodiversity-Bioindicator program, assessed the state of bioindicator played by earthworms in relation to three agricultural managements (organic, traditional, fertilized). It appeared that (i) earthworms were more abundant under organic and traditional agrosystems compared to fertilized one with sewage sludge, (ii) traditional agrosystem allowed the highest specific richness. However, it appeared difficult to compare different agricultural managements without taking into account the land uses and the pedological context. Thus, within each agricultural management, a new study scale was added, integrated agricultural use practices and pedological context. This last approach demonstrated that the structure of earthworm communities (abundance, biomass, specific and ecological structures) was influenced by agricultural managements but also and strongly by agricultural use practices and pedological variability. These results are discussed in terms of relevance of earthworm as soil indicators.