TILLAGE SYSTEMS AND SOIL COMPACTION - THEIR IMPACT ON ABUNDANCE AND VERTICAL-DISTRIBUTION OF ENCHYTRAEIDAE

We quantified the development of Enchytraeidae (potworms) abundances a nd 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) co nventional tillage with spading machine in two depths (CT (shallow) an d CT (deep)). Three plots of each tillage system were mechanically com pacted by wheeling with graded loads: 0 t, 2 x 2.5 t, 6 x 5 t (wheelin g frequency x wheel load) in early spring 1995. CS had a positive effe ct on the abundances. The different tillage depth of the systems used influenced the vertical distribution. Soil compaction resulted in sign ificantly lower individual numbers and a disturbed vertical distributi on. The abundances did not regenerate in one annual cycle on the mecha nically 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 effe cts on soil properties. Furthermore, there are hints towards an increa sed sensitivity to soil frost events in compacted CT plots. (C) 1998 E lsevier Science B.V. All rights reserved.