Millipedes and earthworms increase the decomposition rate of N-15-labelledwinter rape litter in an arable field

Effects of millipedes and earthworms on the decomposition of N-15-labelled litter of winter oilseed rape were investigated in a microcosm field experi ment over a period of 264 days on an oat field near Gottingen managed by in tegrated farming. A total of 32 microcosms were filled with defaunated soil. N-15-labelled ra pe litter was placed either on top of the soil or buried into the soil simu lating mulching and ploughing, respectively. To the microcosms nine adult i ndividuals of Blaniulus guttulatus (Diplopoda) and two of Aporrectodea cali ginosa (Lumbricidae) were added separately or in combination. In general, the presence of the animals accelerated the decomposition rate of the litter material. The effects were most pronounced in the presence of Aporrectodea caliginosa. The total amount of nitrate, ammonium and the amo unt of N-15 leached from the microcosms was increased in the presence of ea rthworms or of both earthworms and millipedes, Both species proved to be im portant members of the detritus food web of the agricultural system studied .