The quality of exogenous organic matter: Short-term influence on earthworm abundance

On a field experiment, started in spring 2005, we examined the influence of different types or qualities of exogenous organic matter (farmyard manure, cattle slurry and three different types of compost, compared with mineral fertilization, and two unfertilized treatments, cropped and uncropped) on the earthworm density and biomass. Earthworms were sampled with mustard powder and subsequent handsorting at the start of the experiment and one year (i.e. two organic matter applications) later. The organic matter applications had a significant effect on the earthworm populations. Earthworm abundance was highest on all organically amended plots, while the lowest number and biomass was found on plots without fertilization. On the latter earthworm number and biomass were equal to or lower than the initial situation. The highest earthworm biomass was recorded on plots amended with farmyard manure. There were indications too that the presence of a crop and the crop performance have an effect on the earthworm populations.