Dissolved nitrous oxide (N2O) dynamics in agricultural field drains and headwater streams in an intensive arable catchment

Hama-Aziz, Zanist Q., Hiscock, Kevin M. and Cooper, Richard J. (2017) Dissolved nitrous oxide (N2O) dynamics in agricultural field drains and headwater streams in an intensive arable catchment. Hydrological Processes, 31 (6). 1371–1381. ISSN 0885-6087

[img]
Preview
PDF (Accepted manuscript) - Submitted Version
Download (1MB) | Preview

Abstract

Indirect nitrous oxide (N2O) emissions produced by nitrogen (N) leaching into surface water and groundwater bodies are poorly understood in comparison to direct N2O emissions from soils. In this study, dissolved N2O concentrations were measured weekly in both lowland headwater streams and subsurface agricultural field drain discharges over a two-year period (2013–2015) in an intensive arable catchment, Norfolk, UK. All field drain and stream water samples were found to have dissolved N2O concentrations higher than the water–air equilibrium concentration, illustrating that all sites were acting as a net source of N2O emissions to the atmosphere. Soil texture was found to significantly influence field drain N2O dynamics, with mean concentrations from drains in clay loam soils (5.3 µg N L-1) being greater than drains in sandy loam soils (4.0 µg N L-1). Soil texture also impacted upon the relationships between field drain N2O concentrations and other water quality parameters (pH, flow rate, and nitrate (NO3) and nitrite (NO2) concentrations), highlighting possible differences in N2O production mechanisms in different soil types. Catchment antecedent moisture conditions influenced the storm event mobilisation of N2O in both field drains and streams, with the greatest concentration increases recorded during precipitation events preceded by prolonged wet conditions. N2O concentrations also varied seasonally, with the lowest mean concentrations typically occurring during the summer months (JJA). Nitrogen fertiliser application rates and different soil inversion regimes were found to have no effect on dissolved N2O concentrations, whereas higher N2O concentrations recorded in field drains under a winter cover crop compared to fallow fields revealed cover crops are an ineffective greenhouse gas emission mitigation strategy. Overall, this study highlights the complex interactions governing the dynamics of dissolved N2O concentrations in field drains and headwater streams in a lowland intensive agricultural catchment.

Item Type: Article
Uncontrolled Keywords: nitrous oxide,nitrate,nitrification,denitrification,river,tile drain
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Pure Connector
Date Deposited: 01 Feb 2017 02:18
Last Modified: 22 Apr 2020 02:37
URI: https://ueaeprints.uea.ac.uk/id/eprint/62264
DOI: 10.1002/hyp.11111

Actions (login required)

View Item View Item