ISSN:
1573-5036
Keywords:
Azotobacter
;
Captan
;
nitrification
;
nodulation of legumes
;
soil microorganisms
;
urea hydrolysis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Captan was applied to laboratory-incubated agricultural soil and to bacterial cultures to determine its effects on total counts of soil microorganisms, nitrification, ammonification of urea and asymbiotic dinitrogen fixation. In Captan-treated soils, total count of fungi, bacteria and actinomycetes decreased significantly only at a relatively high fungicide concentration (1000 μg.g−1). Fungi and actinomycetes were more affected than bacteria. While oxidation of ammonia in an enriched, actively nitrifying culture was almost totally inhibited by Captan, ammonification of urea in incubated soil was only partly depressed. The depressing effect of Captan was more pronounced in cultures of Micrococcus than in those of Proteus. Asymbiotic dinitrogen fixation in nutrient-ammended soil was promoted during the first week and depressed on prolonged exposure to the fungicide depending on its first concentration. In autoclaved Azotobacter-inoculated soil a similar but less pronounced effect was noticed. Fixation by Azotobacter caltures was insensitive to Captan. In contrast, growth ofRhizobium phaseoli, R. leguminosarum andR. japonicum in yeast-extract-mannitol medium was adversly affected by Captan, particularly at 200 μg.ml−1. Nodulation of pea and mung bean (1 month old potted plants) grown from surface-sterilized inoculated seeds in aptan-treated soil was also significantly depressed. Both total number of nodules decreased with increasing concentration of the fungicide, but the inhibitory effect was more pronounced in the number of effective nodules.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02370709
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