Nitrification activity in acid soils of north-eastern Victoria, Australia, as affected by liming and phosphorus fertilisation

Abstract

A short-term nitrification assay (SNA) was used to measure the activity of soil nitrifiers and their response to pH change in acid pasture soils (pH 4.8-5.3 in water) at the sites of Maindample and Ruffy in north-eastern Victoria, Australia. Changes in soil pH associated with lime applications in the field resulted in a change in the optimum pH (pHopt) of the nitrifying organisms in the range 4.93-6.94. Nitrification in these soils was predominantly autotrophic, and rates increased from 0.18 to 0.93 μg NO 3--N/g.h with increasing pH. The strong positive correlation between field soil pH and the respective pHopt values suggested that the indigenous nitrifier population had adapted to the chan..