M. Srinivasulu, M. Madakka, G. Jaffer Mohiddin and V. Rangaswamy
Abstract
A laboratory experiment was conducted to study the effect of the monocrotophos, chlorpyrifos alone and in combination with mancozeb and carbendazim in two soils, collected from a fallow groundnut (Arachis hypogaea L.) field. The activity of urease, in terms of ammonia formed from urea was more pronounced in soil samples treated with 2.5 kg ha-1 and 5.0 kg ha-1 of the monocrotophos alone and in combination with mancozeb, and chlorpyrifos alone and in combination with carbendazim respectively, but at higher concentrations of 7.5 and 10 kg ha-1 were toxic to urease activity. Where as the activity of urease was higher in red soil, received the monocrotophos in combination with mancozeb at 5.0 kg ha-1 and chlorpyrifos in combination with carbendazim at 2.5 kg ha-1 in black soil, incubated for 20 days. The enzyme activity was drastically decreased on prolonged period of incubation up to 30 and 40 days.