Validation of Tropical Artificial Soil by Ecotoxicological Assessment of the Effect of Potash on Eisenia fetida

Abstract

Abstract
Ecotoxicity tests provide a direct measure for the effects of chemicals to earthworms and help to establish adverse ecological effects. The research methodology recommended by the Organisation for Economic Co-operation and Development (OECD) Guideline for testing of chemicals no. 207 meets the most criteria expected for ecotoxicological testing except the testing condition and the organic matter. The guideline was initially developed by temperate countries like Europe and North America, thus constructed the testing condition as 20°C and the organic matter as sphagnum peat which is commonly available in those countries. But these two criterions are difficult to be followed in tropical countries like India. Thus there arises a need of modifying these criterions for toxicity studied in tropical regions. In this study a trial was made for substituting the fermented coir pith for sphagnum peat and the validation of the modified tropical artificial soil (TAS) was done by conducting ecotoxicity studies on Eisenia fetida (Savigny, 1826) against an inorganic fertilizer, potash under tropical condition, i.e., 28±2°C. The performed study showed that the fertilizer potash determined lower earthworm mortality and biomass loss in TAS comparing to OECD soil for all tested concentration levels of the fertilizer. LC50 of potash was established at 4.5 g concentration (14 days) in TAS and it was 2.5 g in OECD soil representing the fact that OECD soil itself is more toxic under tropical condition. The number of juveniles produced in OECD soil was also significantly reduced (p < 0.05) than in TAS. Thus it was concluded that the fermented coir pith was more suitable for ecotoxicity studies under tropical condition than sphagnum peat.
Keywords: tropical artificial soil, Eisenia fetida, potash, acute and chronic toxicity tests