The effect of different N substrates on biological N2O production from forest and agricultural light textured soils

Abstract

N2O emissions from two slightly alkaline sandy soils, from arable land and a woodland, were determined in a laboratory experiment in which the soils were incubated with different sources of nitrogen, with or without glucose, and with 0, 1 and 100 mL C2H2 L-1. Large differences in the rate of N2O production were observed between the two soils and between the different N treatments. The arable soil showed very low N2O emissions derived from reduced forms of N as compared with the N2O which was produced when the soil was provided with NO 2 - or NO 3 - and a C source, suggesting a very active denitrifier population. In contrast, the woodland soil showed a very low denitrification activity and a much higher N2O production derived from the oxidation of NH 4 + and reduction of NO 2 - by some processes probably mediated by autotrophic or heterotrophic nitrifiers or dissimilatory NO 2 - reducers. In both soils, the highest N2O emissions were induced by NO 2 - addition. Those emissions were demonstrated to have a biological origin, as no significant N2O emissions were measured when the soil was autoclaved.