Comparison of chronic toxicity of Lindane (gamma-HCH) to Enchytraeus albidus in two soil types: the influence of soil pH

In this study the influence of soil pH on the reproductive output of Enchyt raeus albidus with and without the presence of a chemical agent in two diff erent soil types was investigated. Three experiments were performed: experi ment 1, in artificial soil only with pH manipulation; experiment 2, in arti ficial soil with pH manipulation and incorporation of lindane; experiment 3 , where two different soils (artificial and natural) with pH manipulation a nd incorporation of lindane were compared. The overall data showed that a l ow soil pH (pH = 4.6) itself reduces significantly the number of juveniles produced by this species. In all cases, the "pH effect" overcomes the effec t of lindane. However, tests with a soil pH value of 5.7 showed that lindan e was very toxic to E. albidus, leading to a marked decrease in the number of juveniles produced. The comparison of the two soil types also showed tha t in addition to the low pH, organic matter content also had an influence o n toxicity. Hints on the influence of several key soil physical and chemica l properties on toxicity data are given, together with the precautions to b e taken when interpreting results from toxicity tests on artificial soils.