Urease activity in rice soils as influenced by moisture regimes and rice rhizosphere

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.