Abstract:
Urease activity in six rice soils of Kerala namely laterite (Oxisol), karappadam (Inceptisol),
kari (Inceptisol), kole (Inceptisol) and black soil (Vertisol) were studied at 60% WHC and under
submergence. The pattern of urea hydrolysis was same at 60% WHC and under submergence.
While the black soil exhibited the highest urease activity, kari soil registered the lowest activity.
When soils were incubated for periods longer than 5 h (at both the moisture regimes) the urea
hydrolysis was complete within two days in laterite, karappadam and kayal soils. For black and
kole soils it took five days and for kari soil 30 days for the completion of urea hydrolysis. The rice
rhizosphere was found to have a positive influence on urease activity and the maximum urease
activity in the rhizosphere was noticed at 60lh day after planting.
