First 20 years of DNDC (DeNitrification DeComposition): Model evolution

Sarah L Gilhespy,Steven Anthony,Laura Cardenas,David Chadwick,Agustin Del Prado,Changsheng Li,Thomas Misselbrook,Robert M Rees,William Salas,Alberto Sanz-Cobena,Pete Smith,Emma L Tilston,Cairistiona F.E Topp,Sylvia Vetter,Jagadeesh B Yeluripati

doi:10.1016/j.ecolmodel.2014.09.004

Abstract

Mathematical models, such as the DNDC (DeNitrification DeComposition) model, are powerful tools that are increasingly being used to examine the potential impacts of management and climate change in agriculture. DNDC can simulate the processes responsible for production, consumption and transport of nitrous oxide (N2O). During the last 20 years DNDC has been modified and adapted by various research groups around the world to suit specific purposes and circumstances. In this paper we review the different versions of the DNDC model including models developed for different ecosystems, e.g. Forest-DNDC, Forest-DNDC-Tropica, regionalised for different areas of the world, e.g. NZ-DNDC, UK-DNDC, modified to suit specific crops, e.g. DNDC-Rice, DNDC-CSW or modularised e.g. Mobile-DNDC, Landscape-DNDC. A ‘family tree’ and chronological history of the DNDC model is presented, outlining the main features of each version. A literature search was conducted and a survey sent out to c. 1500 model users worldwide to obtain information on the use and development of DNDC. Survey results highlight the many strengths of DNDC including the comparative ease with which the DNDC model can be used and the attractiveness of the graphical user interface. Identified weaknesses could be rectified by providing a more comprehensive user manual, version control and increasing model transparency in collaboration with the Global Research Alliance Modelling Platform (GRAMP), which has much to offer the DNDC user community in terms of promoting the use of DNDC and addressing the deficiencies in the present arrangements for the models’ stewardship.

Highlights

Nitrous oxide (N2O) is a powerful greenhouse gas (GHG) and is implicated in depletion of the stratospheric ozone layer
The purpose of this paper is to review the state of the DNDC model to address the issues discussed above by, (1) exploring and describing the main features of different DNDC versions and how they have evolved and are related to each other, (2) assessing information on model use and how the model has been developed to answer questions in ecosystem modelling, and (3) highlighting strengths, weaknesses and potential improvements for the model
Numerous changes have been made to the DNDC model by its developers in response to comments and requests from worldwide users aiming to bridge gaps either in functions or regions

Summary

Introduction

Nitrous oxide (N2O) is a powerful greenhouse gas (GHG) and is implicated in depletion of the stratospheric ozone layer. Agriculture contributes 60% of the total N2O emissions (Smith et al, 2007, 2008). Agricultural soils are known to be an important source of N2O through the processes of nitrification and denitrification and are estimated to contribute 6.1% to anthropogenic global warming (IPCC, 2007). Nitrification is the aerobic microbial oxidation of ammonium (NH4+) to nitrite (NO2À) and nitrate (NO3À). Denitrification is the anaerobic microbial reduction of NO3À to NO2À and to the gases nitric oxide (NO), N2O and dinitrogen (N2). Mathematical models are powerful tools that are increasingly being used to examine the potential impacts of management and climate change in agriculture. Where measurements of emissions cannot be obtained, models may be used at the site-scale to interpolate and for nations to extrapolate measurement information, both spatially and temporally, for use in GHG inventories

Objectives

Methods

Results

Conclusion