Urea hydrolysis in oxisols: Effects of substrate concentration, temperature, pH, incubation time and storage conditions

摘要

This study evaluated the kinetics of urease hydrolysis in two different Brazilian soils (Rhodic Oxisols): a typic alumino-ferric Red Latossol and a typic distrophic Red Latosol. The trials were carried out to study the effects of air drying, soil sampling, storage conditions and temperature, pH, time of incubation, and substrate concentration on the urease activity. Results showed that best conditions for soil sample storage after air-drying for a 7-day period were at room temperature or at a temperature of 5 degrees C. For the studied conditions the best incubation time was one hour at 25-30 degrees C, without pH buffering. The ideal urea concentration suggested for the detection of the maximum velocity was 3.3 g L-1 for the typic alumino-ferric Red Latossol and 2.5 g L-1 for the typic distrophic Red Latosol.