EFFECT OF SOIL COMPACTION ON EARTHWORMS (LUMBRICIDAE) IN APPLE ORCHARD SOIL

The effect of soil compaction on earthworms was investigated comparing earthworm populations in trafficked (T) and untrafficked (U) parts of three apple orchards intensively worked for 10, 15 and 20 yr. The results indicated that high traffic intensity (up to 200 passages of farm machinery per year) considerably reduced both earthworm density and biomass. The differences between T and U plots were significant (P < 0.01) except in the case of the orchard intensively worked for 15 yr in respect to biomass, and they could be attributed mainly to a reduction of juvenile worms in T plots. The community structure was also affected; epigeic species showed the decrease in proportion in T compared with U plots, while the proportion of hypogeic ones increased.