Effect of pesticides on microorganisms, enzymatic activity and plant in biochar-amended soil

•Enzymatic activity and ecotoxicity of biochar-amended soil were evaluated.•Effect of pesticides (dicamba and 2,4-D) was also investigated.•Biochar stimulated the activity of enzymes.•Biochar reduced the negative effect of pesticides on the enzymatic activity.•More effective reduction was observed for dicamba than for 2,4-D.

The objective of the study was the determination of the effect of biochar and pesticides (2,4-D and dicamba) on the enzymatic activity and ecotoxicity of soils. The study was realized within the framework of a field experiment in which biochar was applied to soil at two doses, 30 t/ha and 45 t/ha. Soil samples for analyses were taken 17 months after the application of biochar to the soils. In the soil samples the basic physicochemical properties, enzymatic activity and the ecotoxicological properties were analysed. Biochar stimulated the activity of enzymes in almost all experimental treatments. In addition, it also reduced the negative effect of pesticides on the enzymatic activity and on certain microorganisms in the Microbial Assay for Risk Assessment (MARA). More effective reduction of the negative effect was observed for dicamba than for 2,4-D. Depending on the matrix tested (elutaries or solid phase) varied impacts of the biochar and the pesticides on Lepidium sativum were observed. 2,4-D had an additive effect with the biochar, significantly increasing the phytotoxicity of the soil relative to the soil without any biochar content.

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