ABSTRACT
NITRIFICATION IN SOILS OF ÑUBLE, CONCEPCION AND BIOBIO (CHILE)

Jorge Etchevers B., Luis Longeri S. y Juan Venegas M.1
 

The nitrification process was studied in soils of Ñuble, Concepcion and Biobio by a perfusion technique. The percentage of NH4-N nitrified by the different soils ranged from 24 to 76% at the end of a 35-day period. Soils derived from volcanic ashes nitrified more NH4+ than soils derived from sandy alluvial and metamorfic materials but less than a soil originated from fluvio-glacial materials. The nitrification rate was constant throughout the experiment for a particular soil and was significantly and positively correlated with the most probable number of nitrifying bacterias and the concentration of available-P. The nitrification rate was also significantly but negatively correlated with the concentration of extractable-Al.
A substantial decrease of the NH4-N concentration ocurred during the first 24 hours of perfusion. It is suspected that mechanisms other than nitrification were responsible for this decrease.

Keywords:
1Ing. Agr., Ph. D., Profesor de Suelos; Ing. Agr., M. S., Profesor de Microbiología; e Ing. Agr., respectivamente. Departamento de Suelos y Microbiología, Universidad de Concepción, Casilla 537, Chillán, Chile.