Individual study: More deep-burrowing earthworms in arable soil after ten years of reduced tillage than in ploughed soil; an experiment in Welschbillig southern Eifel Germany
Ernst G. & Emmerling C. (2009) Impact of five different tillage systems on soil organic carbon content and the density, biomass, and community composition of earthworms after a ten year period. European Journal of Soil Biology, 45, 247-251
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A replicated, controlled trial near Welschbillig, southern Eifel, Germany (Ernst & Emmerling 2009) found a higher biomass of large deep-burrowing earthworms (Lumbricidae) in arable soils subject to four different types of reduced tillage, compared to ploughed soils, after 10 years. There were 52-79 g deep-burrowing worm/m2 under reduced tillage, compared to 10 g/m2 in ploughed treatments. For two non-inversion tillage treatments, there were greater numbers of deep-burrowing worms. One of these treatments had mulched crop residue on the surface. On average there were 5 deep-burrowing earthworms/m2 in the ploughed treatment, compared to 21-25 deep-burrowing earthworms/m2 with non-inversion tillage. The total number of earthworms was not significantly different between tillage treatments (113-160 earthworms/m2 on average), but total mass of all earthworms was significantly higher in the disc harrow treatment than the ploughed treatment (119 g/m2 compared to 67 g/m2 under ploughing). Five tillage treatments were carried out on two replicate plots each, for ten consecutive years: conventional ploughing to 25 cm depth, non-inversion loosening of topsoil to 15 cm depth, disc harrowing and slightly loosening soil to 15 cm depth, non-inversion tillage with crop residue mulch on the surface, or no tillage with direct sowing of crop. Earthworms were sampled at the end of the experiment in spring 2008, under a winter barley crop.