Temperature effects on N ₂ O and N ₂ denitrification end‐products for a New Zealand pasture soil

Abstract

Denitrification results in the formation of two gaseous end‐products: radiatively active greenhouse gas nitrous oxide (N 2 O) and radiatively inert di‐nitrogen (N 2 ). Measuring N 2 produced by soil microorganisms has historically been difficult because of interference by high background concentrations (780,840 ppm) of atmospheric N 2. Here, we applied a new automated technique for simultaneous measurement of the denitrification end‐products N 2 O and N 2 . We tested the hypothesis that the temperature response function (defined here as Q 10 ) for N 2 O was greater than for N 2 under anaerobic conditions in the laboratory. The Q 10 for N 2 O was 2.0 and the Q 10 for N 2 was 1.4, indicating differences in sensitivity to temperature. Denitrified‐N shifted towards N 2 O as temperature increased. While moisture strongly controls the relative abundance of denitrification end‐products, additional experiments are needed to determine how a wider range of temperatures may affect N 2 O and N 2 . Results could enhance understanding of temperature controls on N 2 O production and consumption processes.