Nitrogen mobilization by earthworms in limed peat soils under Picea sitchensis.
Laboratory experiments were conducted to determine whether common species of earthworms could survive and grow in limed peat for several months. Survival of all earthworm species was greater in the limed (2.5 or 10 t/ha) than unlimed treatments. Aporrectodea caliginosa and Lumbricus terrestris survived better than L. rubellus and Dentrodrilus rubidus with all rates of lime. All earthworm species increased the amount of nitrogen released in leachates from limed and unlimed peat. Nitrate release was significantly greater in treatments with lime and earthworms than with earthworms alone. Aporrectodea caliginosa was inoculated into limed deep peat soils under Picea sitchensis in field experiments at Kershop forest, Cumbria, UK. Total earthworm biomass was sustained over 12 months in the limed treatments. Only 4% remained in the unlimed plots. A. caliginosa in limed soil increased leachate nitrogen release, mainly as nitrate. The enhanced mineralization was expected to enhance tree growth.