Fig. 1 in Studying earthworms (Annelida: Oligochaeta) in South Africa

Fig. 1. Earthworm sampling. (A) The most common method is for plots to be dug up, the soil sorted by hand, and earthworms removed. (B) An alternative method is to apply chemical irritants (e.g. mustard solution) to a plot and the earthworms collected once they emerge from the soil. (C) Sorting, cleaning and processing earthworms in the field is a major component of sampling. Decisions as to the size of plot used, how deep the plots are dug, and which chemicals are used in which concentrations, as well as the timing of the sampling, all need to be adjusted depending on the goals of sampling. For large individuals (and anecic species) different sampling methods are needed (see text).