Changes in the abundance and diversity of earthworms in hill soils under different long-term fertiliser and sheep stocking regimes

This study examined the earthworm community in permanent pastures at three self-contained farmlets that make up the long-term P fertiliser and sheep grazing study located at Ballantrae Hill Country Research Station. Thirty five years after the study was established, earthworm abundance was lower at the farmlet receiving no fertiliser since 1979 (LFNF, 219 m−2), compared to that receiving 125 kg SSP/ha/year (LFLF, 384 m−2) or 375 kg SSP/ha/year (HFHF, 428 m−2). Earthworm species diversity increased from two in 1979, to nine in 2014, as a result of both accidental and deliberate anthropogenic earthworm introductions. Across all farmlets earthworm abundance was closely associated with pasture production, as well as several pasture attributes and soil variables, particularly those influenced by slope. Maximising the contribution of soil fauna to soil function in hill country requires recognising the influence of slope on earthworm habitats and associated resource availability.