Heterotrophic and autotrophic nitrification in two acid pasture soils

Abstract

Laboratory incubation experiments, using ¹⁵N-labeling techniques and simple analytical models, were conducted to measure heterotrophic and autotrophic nitrification rates in two acid soils (pH 4.8-5.3; 1/5 in H₂O) with high organic carbon contents (6.2-6.8% in top 5 cm soil). The soils were from pastures located near Maindample and Ruffy in the Northeast Victoria, Australia. Gross rates of N mineralization, nitrification and immobilization were measured. The gross rates of autotrophic nitrification were 0.157 and 0.119 micrograms N g⁻¹ h⁻¹ and heterotrophic nitrification rates were 0.036 and 0.009 micrograms N g⁻¹ h⁻¹ for the Maindample and Ruffy soils, respectively. Heterotrophic nitrificat..