BURROWING ABILITY OF THE EARTHWORM APORRECTODEA-LONGA LIMITED BY SOIL COMPACTION AND WATER POTENTIAL

Adult earthworms (Aporrectodea longa) were maintained for 199 days in soil columns (h = 30 cm; empty-set = 10 cm) where the water potential ranged from -7 to -65 kPa and compaction from 50 to 350 kPa. The weight of casts on the soil surface was measured at the end of two periods of activity (spring and autumn). Cast production increased with bulk density, but the activity of earthworms was limited both by the mechanical strength of the soil and by decreasing water potential. The results obtained in the laboratory conditions of this study were consistent with field observations on casting and burrowing activities. The effects of water potential and soil compaction on these activities were estimated.