By: R. Pal,K. Chakrabarti, A. Chakraborty, A.
Chowdhury
Clay loam soil from agricultural fields of alluvial (AL) soil (typic udifluvent) and coastal saline (CS) soil (typic endoaquept) were investigated for the degradation and effect of pencycuron application at field rate (FR), 2-times FR (2FR) and 10-times FR (10FR) with and without decomposed cow manure (DCM) on soil microbial variables under laboratory conditions. Pencycuron degraded faster in CS soil and in soil amended with DCM. Pencycuron spiking at FR and 2FR resulted in a short-lived (in case of 10FR slightly longer) and transitory toxic effect on soil microbial biomass-C (MBC), ergosterol content and fluorescein diacetate hydrolyzing activity (FDHA). Amendment of DCM did not seem to have any counteractive effect of the toxicity of
pencycuron on the microbial variables. The ecophysiological
status of the soil microbial communities as expressed by microbial metabolic
quotient (qCO2) and microbial respiration quotient (QR) changed, but for a short
period, indicating pencycuron induced disturbance. The duration of this
disturbance was slightly longer at 10FR. Pencycuron was more toxic to the
metabolically activated soil microbial populations, specifically the fungi. It
is concluded that side effects of pencycuron at 10FR on the microbial variables
studied were only short-lived and probably of little ecological
significance.
Clay loam soil from agricultural fields of alluvial (AL) soil (typic udifluvent) and coastal saline (CS) soil (typic endoaquept) were investigated for the degradation and effect of pencycuron application at field rate (FR), 2-times FR (2FR) and 10-times FR (10FR) with and without decomposed cow manure (DCM) on soil microbial variables under laboratory conditions. Pencycuron degraded faster in CS soil and in soil amended with DCM. Pencycuron spiking at FR and 2FR resulted in a short-lived (in case of 10FR slightly longer) and transitory toxic effect on soil microbial biomass-C (MBC), ergosterol content and fluorescein diacetate hydrolyzing activity (FDHA). Amendment of DCM did not seem to have any counteractive effect of the toxicity of
pencycuron on the microbial variables. The ecophysiological
status of the soil microbial communities as expressed by microbial metabolic
quotient (qCO2) and microbial respiration quotient (QR) changed, but for a short
period, indicating pencycuron induced disturbance. The duration of this
disturbance was slightly longer at 10FR. Pencycuron was more toxic to the
metabolically activated soil microbial populations, specifically the fungi. It
is concluded that side effects of pencycuron at 10FR on the microbial variables
studied were only short-lived and probably of little ecological
significance.Yangzhou pioneer chemical CO.,LTD
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