Vertical distribution of denitrification activity in an Andisol upland field and its relationship with dissolved organic carbon: Effect of long-term organic matter application

Abstract

The denitrification enzyme activity (DEA) and dissolved organic carbon (DOC) concentration in soil from the plow layer to a depth of 5 m were measured in an Andisol upland field to which several types of organic matter had been continuously applied for 20 years. The DEA was measured using the acetylene inhibition method. The DEA values at the plow layer were 0.15-0.16 mmol N kg -1 per day in the chemical fertilizer plots. Higher DEA values were detected in all the plots to which organic matter had been applied: 0.19 mmol N kg -1 per day in the rice straw manure plot and 0.81 mmol N kg -1 per day in the pig dung plot. In contrast, lower DEA values were detected in the non-nitrogen and non-fertilizer plots, that is, 0.02 and 0.03 mmol N kg -1 per day, respectively. The DEA values correlated with total organic carbon (TOC) values, total nitrogen (T-N) values, nitrogen mineralization rate, and available P measured using the Bray No.2 test; a highly significant correlation coefficient was obtained for the DOC (pH 5.5-6.0) calibrated with pH-DOC relations. In all plots examined, the plow layers showed the highest DEA values, and these dropped abruptly between depths of 0.5 and 1.0 m. At depths lower than 1.0 m, the DEA ranged from 10 -4 to 10 -5 mmol N kg -1 per day in all plots despite remarkable differences in DEA in the plow layers among plots. These observations suggested that the application of organic matter enhances the organic carbon content and DEA values in the plow layer, the extent of which is largely influenced by the variety and quantity of the applied organic matter. However, the properties of the applied organic matter did not influence the organic carbon contents or the DEA values at the subsurface. Furthermore, our investigations confirmed that subsurface denitrification did not substantially decrease the nitrate concentration during downward infiltration.

Impacts of natural factors and farming practices on greenhouse gas emissions in the North China Plain: A meta‐analysis

“…Compared with M, annual N 2 O emissions significantly increased under M+O (17.0%; p < .05; Figure a), probably because of the increased supply of C and anaerobic conditions favoring denitrification (Anderson & Levine, ; Kamewada, ; Velthof, Kuikman, & Oenema, ). O appeared to reduce N 2 O emissions but also significantly decreased crop yield ( p < .05), because of the lack of synchronicity of N supply with crop demand under O treatment (Skinner et al., ; Tuomisto, Hodge, Riordan, & Macdonald, ).…”

Potential of denitrification and nitrous oxide production from agricultural soil profiles (Seine Basin, France)

“…Most research on subsoil denitrification has concentrated on riparian systems (Hill et al 2000;Davis et al 2008;Bernal et al 2007;McCarty et al 2006) more than croplands (Kamewada 2007;Davis et al 2008). The associated N 2 O production is even more scarcely reported in the literature.…”

Nitrous Oxide (N2O) Emissions from Subsurface Soils of Agricultural Ecosystems

“…Other evidence for significant subsurface N 2 O production includes denitrification enzyme activity (DEA; for example, Castle and others 1998;Kamewada 2007) and isotopic concentrations of N 2 O in laboratory soil columns (Clough and others 1998) and in situ (Van Groenigen and others 2005b). DEA usually declines rapidly with soil depth.…”

“…DEA usually declines rapidly with soil depth. Kamewada (2007), for example, observed an abrupt drop in DEA in samples from an Andisol soil at depths between 0.5 and 1 m, below which DEA was low and constant to 5 m, leading to a conclusion that subsurface denitrification was negligible. Others have also observed substantial decreases in volumetric (per m 3 ) or gravimetric (per kg) denitrification rates with depth in different environments (Hashimoto and Niimi 2001;Murray and others 2004;Goldberg and others 2008).…”