Passive Techniques

Hand digging and sorting, which is the most commonly used method for quantitative sampling of earthworms, involves digging pits of known volume (e.g., 25 by 25 by 25 cm), breaking the soil by hand, and collecting all earthworms and cocoons found. Collected specimens are immediately preserved in 70% ethanol or 5% formalin for later counting and identification, or they may be kept alive in cool, moist media for use in experiments. Washing and sieving is an elaboration of hand sorting: the soil is dispersed in water, poured through a sieve, and the earthworms and cocoons hand picked from the sieve contents. Bouché and Beugnot (1972) describe mechanical approaches to washing and sieving. Flotation of sieve contents in a high-density solution, such as 1.16-1.20 specific gravity MgSO4, is another means of separating earthworms and other soil fauna.

0 0

Post a comment