Structural and functional approach to studying pesticide side-effects on specific soil functions

• Published in: Environmental toxicology and chemistry 2003-04, Vol.22 (4), p.784-790
• Main Authors: Liebich, Jost, Schäffer, Andreas, Burauel, Peter
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Anthraquinones - toxicity; Applied ecology; Applied sciences; Bacteria - drug effects; Bacteria - genetics; Bacteria - isolation & purification; Bacteria - metabolism; Biological and medical sciences; Biological and physicochemical properties of pollutants. Interaction in the soil; Carbon Radioisotopes; Crop residue; Crops, Agricultural - metabolism; DNA, Bacterial - analysis; DNA, Ribosomal - genetics; Ecotoxicology, biological effects of pollution; Ergosterol - analysis; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Fungicide; Fungicides, Industrial - toxicity; Humic Substances; Humification; McRobial community; Plant Structures - metabolism; Pollution; RNA, Ribosomal, 16S - genetics; Soil - analysis; Soil and sediments pollution; Soil Microbiology; Soil organic matter; Terrestrial environment, soil, air; Time Factors; Zea mays - metabolism
• ISSN: 0730-7268; 1552-8618
• DOI: 10.1002/etc.5620220416

The microbial communities in the soil are responsible for material cycling and thus also for maintaining the fertilityof agricultural soils. In order to assess pesticide side effects on the soil processes, detailed knowledge is required about the structure and function of the soil microflora. Therefore, the degradation and humification of 14C‐labeled maize straw was studied in processoriented microcosms. Apart from a native orthic luvisol, a heat‐treated soil was used that has been freed from organic carbon by incineration at 600°C. Microbial communities involved in the turnover of the crop residues were investigated using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA sequences. Both 13C‐nuclear magnetic resonance (NMR) spectroscopy and gel permeation chromatography were used to analyze humic acids produced in the microcosms. To evaluate the sensitivity of the microcosms, the influence of the fungicide dithianon was used in a case study at a concentration of 50 mg/kg. Microbial activity was reduced because of the application of the pesticide, especially in the native soils, while mineralization of 14C‐labeled maize straw was only slightly affected. The buildup of fungal biomass was inhibited for at least three weeks. Despite these effects on the microbial communities, no significant differences in the humification products after 26 weeks of incubation were observed.