Tillage systems and soil compaction - their impact on abundance and vertical distribution of Enchytraeidae

We quantified the development of Enchytraeidae (potworms) abundances and vertical distribution in mechanically stressed soils for 1 year. To assess the effects of soil compaction due to cultivation practice on arable land, two agricultural locations were chosen, differing in soil type, annual rainfall, and soil tillage: (1) conservation tillage (CS) with rotary harrow and conventional tillage (CT) with plough, (2) conventional tillage with spading machine in two depths (CT (shallow) and CT (deep)). Three plots of each tillage system were mechanically compacted by wheeling with graded loads: 0 t, 2 x 2.5 t, 6 x 5 t (wheeling frequency x wheel load) in early spring 1995. CS had a positive effect on the abundances. The different tillage depth of the systems used influenced the vertical distribution. Soil compaction resulted in significantly lower individual numbers and a disturbed vertical distribution. The abundances did not regenerate in one annual cycle on the mechanically compacted plots but vertical distribution did. Because of the low abundances, the Enchytraeidae on the compacted plots cannot fulfil their important function in microstructure development and their effects on soil properties. Furthermore, there are hints towards an increased sensitivity to soil frost events in compacted CT plots. (C) 1998 Elsevier Science B.V. All rights reserved.