Urease activity in soils of central Chile

Manuel Casanova P.1 y Carlos Benavides Z.1

The levels of urease activity in 14 soil samples from the central zone of Chile were determined through a non-buffer measurement of residual urea, in presence of urease inhibitor (phenyl mercuric acetate), after sample incubation of 5 hours at 37 ºC. Activity measurements varied from 56.1 to 160.4 μg of urea/g soil hour, at 37 ºC. According to stepwise analysis, cation exchange capacity (CEC) and organic matter content (OM) are the most important edaphic variables of urease activity (UA):
UA =-1.4714 + 6.7659 [OM] + 1.8394 [CEC]
R2= 0.80
This equation shows the level of soil colloidal (organic and inorganic) protection against enzime biodegradation and other processes leading to urease inactivation; so that each soil has a stable level of urease activity, depending on the soil constituents.

Keywords: urease, urea, enzimatic activity, surface soíl.
1 Departamento de Ingenierla y Suelos, Facultad de Ciencias Agrarias y Forestales. Universidad de Chile, Casilla 1004, Santiago, Chile.