Abstract: A 21-day laboratory incubation experiment was conducted to investigate the impact of pesticides (Triazophos, Butachlor and Jinggangmycin) on a paddy field soil health under controlled moisture (flooded soil) and temperature (25℃) conditions. The electron transport system ETS)/dehydrogenase activity displayed a negative correlation with pesticides concentrations, and the activity was affected adversely as the concentration of the pesticides increased. The higher doses of pesticides, 5 and 10 folds field rates, significantly inhibited ETS activity, while lower rates failed to produce any significant reducing effect against the control. The relative toxicity level of pesticides in decreasing the ETS activity was in the following order: Triazophos>Jinggangmycin>Butachlor, irrespective of their rates of application. The pesticides caused an improvement in the soil phenol content and it increased with increasing the concentration of agrochemicals. The pesticide incorporation did not produce any significant change in soil protein content. The response of biomass phospholipid content was nearly similar to ETS activity. The phospholipid content was decreased with the addition of pesticides in the given order of Triazophos>Jinggangmycin>Butachlor; and the toxicity was in the order: 10 FR (times of field rate)>5 FR>1.0 FR>0.5 FR>control.

Key words: electron transport system activity, phenol, protein, phospholipids, pesticides, paddy soil