Ecotoxicological Evaluation of Forest Biomass Ash on Springtails and Earthworms in Subtropical Soils of Brazil

Abstract

The forest biomass ash used in agriculture as fertilizer has characteristics that can negatively affect the terrestrial environment. This study aimed to evaluate the effect of the application of eucalyptus forest biomass ash on springtails and earthworms in subtropical soils through ecotoxicological tests. The subtropical soils Oxisol and Entisol were used for the ecotoxicological tests of survival and reproduction of springtails (Folsomia candida) and earthworms (Eisenia andrei). The concentrations of forest biomass ash were 0, 5 10 and 20 t ha^-1, based on the recommendation of the application of plant ash as fertilizer. The ecotoxicological results obtained in Oxisol demonstrate that earthworms and springtails are not affected by the presence of ash. In Entisol, the results of sensitivity of the organisms were more evident, and effects were observed from the dose of 5 t ha^-1 for springtails with estimated LC₅₀ of 15.68 t ha^-1 (CI: not calculated) and EC₅₀ of 7.36 t ha^-1 (CI: 7.11-7.62 t ha^-1). Earthworms were affected from 10 t ha^-1, with an estimated EC₅₀ of 11.97 t ha^-1 (CI: 9.49-14.46 t ha^-1). Application of forest biomass ash in the soil negatively affects springtails and earthworms, but the magnitude of the effects is mainly related to characteristics of the soil, amount applied and sensitivity of the species; negative effects of ash application are directly related to the change in soil pH.