engleski

ECOFUN-MICROBIODIV : an FP7 European project to estimate the ecotoxicological impact of low dose pesticide application in agriculture on soil functional microbial diversity

Soil is hosting a tremendous microbial diversity playing a key-role in a number of soil ecosystemic services including nutrient cycling and filtering. In the European Soil Framework Directive pesticides are clearly marked as one of the major threats for soil biodiversity and functioning. In order to guarantee minimum effects of pesticide application on soil microbes, pesticide registration at EU level (Regulation 2006/388) considers the toxicity of pesticides onto non target soil microbes by relying on carbon- and nitrogen-mineralization tests (OECD 216, 217). However these tests do not provide a comprehensive assessment of pesticides onto soil microbes. ECOFUN-MICROBIODIV was a project dedicated to developing and evaluating innovative tools to estimate the ecotoxicological impact of sulphonylurea herbicide nicosulfuron on soil microbial diversity and functioning. In order to gain full insights into the potential toxicity of the targeted herbicide a research consortium was established comprised of teams with expertise in agronomy, soil and environmental chemistry, environmental microbiology, soil molecular biology and biochemistry. Two scenario of exposure were considered (i) Tier I, the worst case scenario, consisting in an experiment conducted in a greenhouse with up to x1000 of the nicosulfuron dose applied and (ii) Tier II, the agronomical scenario, consisting in an experiment conducted in the field (1x, 2x and 5x of nicosulfuron) Agronomical parameters were recorded for both experiments (yield of crop, weeds development, root and shoot biomass of corn). Soil and corn root sampling was carried out all along the experiment. The fate of nicosulfuron was monitored in soil by HPLC-UV. The impact of herbicide was estimated using standard methods aimed at studying the abundance (ISO14240:2), diversity (ISO/TS29843-1), and the activity (TS29843-1) of the soil microflora. In addition, new methods based on direct soil DNA extraction (ISO 11063) were applied to determine herbicide impact on structure and abundance of fungal and bacterial communities, structure, abundance, and activity of the functional communities involved in C and N cycling and on the formation of endomycorhizal symbiosis. Results suggested that for the good understanding of the impact of low-dose herbicide, such as nicosulfuron, on the abundance, structure, diversity, and activity of soil microbial community it is necessary to use tools of different resolution levels. Application of such multidisciplinary approach relying on biochemistry and molecular biology gives a good estimation of the pesticide impact. Results suggested that if the impact of low-dose pesticide would be only considered using the dominant microbial populations it could be underestimated. The consideration of finer approaches allowing to target specifically a functional community or to go deeper in the phylogeny was proven to give a more accurate estimation of the impact of low dose pesticide onto soil microflora.

pesticide; agriculture; microbail community

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