Efficacy and side effects of five sampling methods for soil earthworms (Annelida, Lumbricidae)

In this study, carried out on an experimental meadow in Austria, in non calceric cambisol, five common methods for sampling earthworms were jointly compared for their efficacy (handsorting, formalin, and allyl isothiocyanate (AITC) application, heat extraction in Kempson apparatus, and electrical octet method). Additionally, short- and long-term effects of the non-destructive of these methods (formalin and AITC application, octet method) on soil organisms (microarthropod abundance, phospholipid fatty acids) and shoot and root biomass were analysed. The Kempson extraction yielded the greatest number of individuals, followed by the octet method and handsorting. Formalin and AITC showed lower efficacy, but expelled high numbers of adult earthworms. Whereas AITC scarcely had nontarget effects on soil organisms, formalin negatively affected soil microorganisms and vegetation on the treated plots. The octet method seems to be well applicable especially in protected areas, since it is efficient, non-destructive and does not adversely affect soil organisms. The recommendations for method application are given, depending strongly on the scope of studies, as well as on ecological conditions and legal study site limitations.