title: Modelling nitrous oxide emissions from mown-grass and grain-cropping systems: Testing and sensitivity analysis of DailyDayCent using high frequency measurements.
abstract: The DailyDayCent biogeochemical model was used to simulate nitrous oxide (N2O) emissions from two contrasting agro-ecosystems viz. a mown-grassland and a grain-cropping system in France. Model performance was tested using high frequency measurements over three years; additionally a local sensitivity analysis was performed. Annual N2O emissions of 1.97 and 1.24kgNha-1year-1were simulated from mown-grassland and grain-cropland, respectively. Measured and simulated water filled pore space (r=0.86, ME=-2.5%) and soil temperature (r=0.96, ME=-0.63°C) at 10cm soil depth matched well in mown-grassland. The model predicted cumulative hay and crop production effectively. The model simulated soil mineral nitrogen (N) concentrations, particularly ammonium (NH4+), reasonably, but the model significantly underestimated soil nitrate (NO3-) concentration under both systems. In general, the model effectively simulated the dynamics and the magnitude of daily N2O flux over the whole experimental period in grain-cropland (r=0.16, ME=-0.81gNha-1day-1), with reasonable agreement between measured and modelled N2O fluxes for the mown-grassland (r=0.63, ME=-0.65gNha-1day-1). Our results indicate that DailyDayCent has potential for use as a tool for predicting overall N2O emissions in the study region. However, in-depth analysis shows some systematic discrepancies between measured and simulated N2O fluxes on a daily basis. The current exercise suggests that the DailyDayCent may need improvement, particularly the sub-module responsible for N transformations, for better simulating soil mineral N, especially soil NO3-concentration, and N2O flux on a daily basis. The sensitivity analysis shows that many factors such as climate change, N-fertilizer use, input uncertainty and parameter value could influence the simulation of N2O emissions. Sensitivity estimation also helped to identify critical parameters, which need careful estimation or site-specific calibration for successful modelling of N2O emissions in the study region.
authors.affiliation: French National Institute for Agricultural Research (INRA), Poitou-Charentes, URP3F, 86600 Lusignan, France; French National Institute for Agricultural Research (INRA), Versailles-Grignon, UMR-ECOSYS, 78850 Thiverval-Grignon, France. Electronic address: nimai_senapati@yahoo.com.
authors.forename: Nimai
authors.initials: N
authors.lastname: Senapati
authors.affiliation: French National Institute for Agricultural Research (INRA), Poitou-Charentes, URP3F, 86600 Lusignan, France; French National Institute for Agricultural Research (INRA), Versailles-Grignon, UMR-ECOSYS, 78850 Thiverval-Grignon, France. Electronic address: abad.chabbi@lusignan.inra.fr.
authors.forename: Abad
authors.initials: A
authors.lastname: Chabbi
authors.affiliation: Federal University of Parana, Rua XV de Novembro, 1299 - Centro, Curitiba - PR, 80060-000, Brazil. Electronic address: andregiostri@hotmail.com.
authors.forename: André Faé
authors.initials: AF
authors.lastname: Giostri
authors.affiliation: The James Hutton Institute, Craigiebuckler, Aberdeen, AB15 8QH, Scotland, UK. Electronic address: Jagadeesh.Yeluripati@hutton.ac.uk.
authors.forename: Jagadeesh B
authors.initials: JB
authors.lastname: Yeluripati
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, 23 St Machar Drive, Aberdeen AB24 3UU, UK. Electronic address: pete.smith@abdn.ac.uk.
authors.forename: Pete
authors.initials: P
authors.lastname: Smith
keywords: DailyDayCent; Grain-cropland; Modelling nitrous oxide; Mown-grassland; Sensitivity analysis