Influence of food quality on the physical and chemical properties of detritivorous earthworm casts

Laboratory experiments were conducted with Lumbricus terrestris, Lumbricus rubellus and Dendrobaena octaedra to study the effects of different food sources on physical and chemical cast properties. Earthworm species were kept separately in special microcosms filled with a loamy soil and offered leaves of dandelion (Taraxacum officinale), lupin (Lupinus polyphyllus), rye (Secale cereale), alder (Alnus glutinosa), beech (Fagus sylvatica) and larch (Larix decidua), diets which differed in palatability, C/N-ratios and secondary plant compounds. Cast production was monitored in relation to earthworm species and food. Enzyme activities (acid and alkaline phosphomonesterase), texture, water stable aggregation and tensile strength of casts were compared with those of the soil. Water stable aggregation was influenced by the food source and the earthworm species. The tensile strength of the casts was also species specific. Although D. octaedra produced the highest and L. terrestris the lowest amount of water stable aggregates, the tensile strength of the casts was lowest for D. octaedra and highest for L, terrestris. (C) 1998 Elsevier Science B.V.