Liao_2002_J.Environ.Sci.(China)_14_309

A laboratory incubation study was carried out to elucidate the dynamic response of insecticide (triazophos) on a paddy field soil health under controlled moisture (flooded soil) and temperature (25 degrees C). The insecticide was applied at five levels that were 0.0 (control), 0.5 field rate (FR), 1.0 FR, 5.0 FR, and 10.0 FR, where FR was 1500 ml/hm2, and the parameters were studied at 1, 4, 7, 14, and 21 days after treatments' addition. The electron transport system (ETS)/dehydrogenase activity exhibited a negative correlation with insecticide concentrations, and the activity affected adversely as the concentration increased. The higher doses of 5 and 10 field rates significantly reduced the ETS activity, while lower rates failed to produce any significant inhibiting effect against the control. The toxicity of insecticide decreased towards decreasing the ETS activity with the advancement of incubation period. The insecticide caused an improvement in the soil phenol content and it increased with increasing concentration of insecticide. The insecticide incorporation applied at various concentrations did not produce any significant change in soil protein content and it remained stable throughout the incubation period of 21-days. The response of biomass phospholipid content was nearly similar to ETS activity. The phospholipid content was decreased with the addition of insecticide and the toxicity was in the order: 10 FR (field rate) > 5 FR > 1.0 FR > 0.5 FR > control and it also decreased with incubation period.