Enchytraeid worms were kept in <0.3 mm sieved sandy loam subsoil mixed with ground wheat, for 6 weeks at 16°C. Sieved soil with organic matter but without worms was also incubated. The soil was then allowed to air-dry slowly during 6 weeks. Enchytraeid casts were collected from the surface of the soil with worms, and the remaining soil was separated into three size fractions by dry sieving. All size fractions were analysed for stability and %C, and mineralisation potential. The amount of soil in the fraction > 0.3 mm (including the casts) was larger in the presence of enchytraeid worms, at the cost of soil from the fraction 0.3 0.03 mm. The %C in both soils was highest in the fraction < 0.03 mm. Activity of enchytraeids significantly decreased the %C in the fraction > 0.3 mm. Fresh excrements, representing 0.5% of the soil, were very high in organic matter content. Mineralisation (expressed as percentage of C that was mineralised) was highest in the fraction <0.03 and lowest in the 0.3-0.03 fraction. Excrements showed very high mineralisation rates. Enchytraeid activity enhanced mineralisation in the fraction > 0.3 ram. Aggregates > 0.3 mm from the treatment with worms dispersed less clay after shaking with water than those from the treatment without worms. Although the influence of enchytraeid worms on total C-content and mineralisation was small, the changes in C of the different size fractions showed that enchytraeids influenced the active fraction of the C in the soil considerably by consuming litter, thereby locating it inside soil aggregates and linking the organic matter to clay particles.
- organic compounds
- soil chemistry