Some effects of diazinon on the microflora of submerged soils
SummaryThe application of diazinon, an organophosphorus insecticide, at the rate of 2 kg and 20 kg active ingredient per hectare to submerged Maahas clay significantly stimulated the actinomycete population. A distinct zone of brown pigmentation formed in that part of the profile commonly referred to as the oxidized layer. A profuse growth of actinomycetes developed from the soil samples of this pigmented zone when streaked onto the nutrient agar. A visible increase in algal populations was noted in the standing water of the diazinon-treated soil.
The distribution and persistence of diazinon applied to plant and soil and its influence on rhizosphere and soil microflora
Summary1. Evidence was obtained of the rapid translocation of radioactive Diazion through bean plants and its emergence in bean root exudates maintained under sterile conditions.2. The presence of bean rhizosphere microflora did not appear to be a factor in the metabolism of Diazinon by the bean plant.3. Diazinon applied at the rate of 3 lbs per acre to soil under non-sterile conditions persisted for as long as 180 days after application. No Diazinon was detectable after 10 weeks in soil receiving 0.3 lbs per acre.4. Diazinon or its degradation products exerted a selective effect common to both soil and rhizosphere microflora which expressed itself in the selective enrichment of a cocoidal rod. Numbers of fungi seemed unaffected by the presence of Diazinon. After 180 days a large number of the genus Streptomyces appeared as a seeming climax population.5. The predominant microbial isolate utilized Diazinon as a sulfur, phosphorus, carbon and nitrogen source in that order of preference. The biodegradability of Diazinon was conditioned by its solubilization in a suitable carrier, and by the presence of an additional carbon source.
Nitrogen-fixing microorganisms in paddy soils: VI
Abstract In the preceeding paper (1), it was reported that when R. capsulatus is mixed with B. subtilis, in spite of no nitrogen fixation in separate cultures, by using a glycerol or starch medium, the combination was able to fix molecular nitrogen and it seems that there is a correlation between the production of pyruvic acid and the nitrogen fixation in the mixed culture.