Importance of food quality on selected enzyme activities in earthworm casts (Dendrobaena octaedra, Lumbricidae)

Dehydrogenase (DHA), acid (SPA) and alkaline (APA) phosphomonesterase activ ities in the casts of Dendrobaena octaedra were analysed while the animals were offered one of six different food sources. The food consisted of air d ried leaves of dandelion, lupin, rye, alder, beech and larch. The food cons umption rate of the earthworms lay between 11.1 mg (dandelion) and 0.3 mg d .w. g(-1) f w d(-1) (larch) while the cast production varied between 252 mg (dandelion) and 835 mg d.w. g(-1) f.w. d(-1) (beech). A deterioration of t he food quality caused a reduction of the food consumption rate, but simult aneously the mean turnover rate of soil aggregates was enhanced. The enzyme activities were influenced by the food which affected the specific nutrien t state of the casts. DHA, SPA and APA were significantly correlated with t he organic C and the total N content of the casts. Interenzymatic correlati ons illustrated the applicability of the three enzyme activities as useful indicators of the influence of earthworms and their food on soil quality. ( C) 2000 Elsevier Science Ltd. All rights reserved.