Untersuchungen zum Einfluss einer Pflanzenschutzmittelspritzfolge auf das Rückstandsverhalten von Terbutryn und die mikrobielle Aktivität im Boden. Teil II. Beeinflussung der mikrobiellen Aktivität |
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| Authors: | B AUSPURG† W PESTEMER R HEITEFUSS |
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| Institution: | Institut für Unkraulforschung der Biologischen Bundesatalt für Land- und Forstwirtschaft, Messeweg 11/12, D-3300 Braunschweig, FRG;Institut für Pflanzenpathologie und Pflanzenschutz der Georg-August-Universität Götingen, Grisebachstr. 6, D-3400 Göttingen, FRG |
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| Abstract: | Studies on the effect of a pesticide spray sequence on the behaviour of terbutryn residues and on soil microbial activity. Part II. Influence on microbial activity In laboratory incubation experiments (at 10 and 20°C and 30 and 60% soil water-holding capacity) soil microbial activities (dehydrogenase, respiration after glucose amendment and nitrogen transformations) were scarcely affected by 20·9 and 28·0 mg kg?1, respectively, of terbutryn in two soils of different sorption properties. In contrast, dinosebacetate, alone or mixed with terbulryn, triadimefon or parathion, inhibited dehydrogenase activity and respiration even at a low rate of application (2·87 mg kg?1). Following application of a 10 times higher rate to a highly adsorbent soil there was an initial inhibition of nitrification followed by an enhanced rate of nitrogen mineralization. Triadimefon and parathion, alone and in combination with other pesticides, caused both stimulation and inhibition of microbial activity; the reason is not clear. The effects on dehydrogenase and respiration were confirmed in field experiments. Dehydrogenase activity was the most sensitive and so could be a useful test for the side-effects of pesticides on soil micro-organisms. Additional work on nitrogen transformations is needed to interpret the results. |
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