Evaluating the effect of liming on N2O fluxes from denitrification in an Andosol using the acetylene inhibition and 15N isotope tracer methods

Abstract

We assessed the effect of liming on (1) N2O production by denitrification under aerobic conditions using the 15N tracer method (experiment 1); and (2) the reduction of N2O to N2 under anaerobic conditions using the acetylene inhibition method (experiment 2). A Mollic Andosol with three lime treatments (unlimed soil, 4 and 20 mg CaCO3 kg−1) was incubated at 15 and 25 °C for 22 days at 50% and then 80% WFPS with or without 200 mg N kg−1 added as 15N enriched KNO3 in experiment 1. In experiment 2, the limed and unlimed soils were incubated under completely anaerobic conditions for 44 h (with or without 100 mg N kg−1 as KNO3). In experiment 1, limed treatments increased N2O fluxes at 50% WFPS but decreased these fluxes at 80% WFPS. At 25 °C, cumulative N2O and 15N2O emissions in the high lime treatment were the lowest (with at least 30% less 15N2O and total N2O than the unlimed soil). Under anaerobic conditions, the high lime treatment showed at least 50% less N2O than the unlimed treatment at both temperatures with or without KNO3 addition but showed enhanced N2 production. Our results suggest that the positive effect of liming on the mitigation of N2O evolution from soil was influenced by soil temperature and moisture conditions.