title: Influence of insecticides on microbial transformation of nitrogen and phosphorus in Typic Orchragualf soil.
abstract: Four insecticides, viz., BHC, phorate, carbofuran, and fenvalerate, were applied at the rate of 7.5, 1.5, 1.0, and 0.35 kg a.i. ha(-)(1), respectively, to investigate their effects on the growth and activities of N(2)-fixing and phosphate-solubilizing microorganisms in relation to the availability of N and P in laterite (Typic Orchragualf) soil. Insecticides in general, and BHC and phorate in particular, stimulated the proliferation of aerobic nonsymbiotic N(2)-fixing bacteria and phosphate-solubilizing microorganisms and also their biochemical activities, such as nonsymbiotic N(2)-fixing and phosphate-solubilizing capacities, which resulted in greater release of available N (NH(4)(+) and NO(3)(-)) and P in soil. All the insecticides were persistent in soil for a short period of time, and the rate of dissipation was highest for fenvalerate followed by phorate, carbofuran, and BHC, depicting the half-lives (T(1/2)) 8.8, 9.7, 16.9, and 20.6 days, respectively. The insecticides followed first-order reaction kinetics during their dissipation in soil.
authors.affiliation: Department of Agricultural Chemistry and Soil Science, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, India.
authors.forename: A C
authors.initials: AC
authors.lastname: Das
authors.forename: D
authors.initials: D
authors.lastname: Mukherjee
mesh_terms: D007306:Insecticides / Q000494:pharmacology*; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation / Q000187:drug effects*; D010758:Phosphorus / Q000378:metabolism*; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology
chemical_list: D007306:Insecticides; D012987:Soil; D010758:Phosphorus; D009584:Nitrogen