EVALUATION OF N2O EMISSIONS BY DNDC MODEL FOR SANDY LOAM SOILS OF DANUBIAN LOWLAND

Ján Horák,Bernard Šiška

doi:10.3846/16486897.2006.9636894

Abstract

Except for food production the sector of agriculture contribute significantly to emissions of some Greenhouse gases (GHGs), especially N2O. Agricultural practices (especially increase of N consumption in the sector) are now recognized as a major factor influencing increase of N2O emissions into the atmosphere. Estimates of greenhouse gas emissions from the agricultural sector both at a local and regional level are necessary to create possible mitigation strategies with respect to environmental efficiency and economic possibility. We used the DNDC (DeNitrification and DeComposition) model that simulates a full carbon (C) and nitrogen (N) balance, including different C and N pools, and the emissions of all relevant trace gases from soils as NH3, N2O, NO, NO2 and N2. However, for this study only N2O was considered. Intergovernmental Panel on Climate Change (IPCC, 1997) includes methodologies for calculating both direct and indirect emissions of N2O related to agricultural production. Finally, the modeled emissions by DNDC were compared with those estimated according to IPCC methodology at a regional level. The rules of a good practice in GHGs inventory in agriculture were taken into account. The N2O emissions estimated by DNDC model ranged 0,09–0,68 kg N2O‐N/ha yr with an average value of 0,28 kg N2O‐N/ha yr. The N2O emissions estimated according to IPCC methodology ranged 0,46–2,86 kg N2O‐N/ha yr with an average value of 1,66 kg N2O‐N/ha yr. Simulated N2O emissions were lower than the N2O emissions estimated by IPCC methodology (1997). The simulated N2O emissions ranged 0,04–0,51 % of the total N applied to a field as a mineral N‐fertilizer. If DNDC and IPCC emissions are compared in this study, it can be concluded that simulated (DNDC) emissions are in the range of default emission factors (1,25 ±1 %) defined by IPCC methodology (1997), except for 2002.

Highlights

With regard to global climate change, soils are of a significant importance as sources for atmospheric trace gas, such as nitrous oxide (N2O)
If DNDC and Intergovernmental Panel on Climate Change (IPCC) emissions are compared in this study, it can be concluded that simulated (DNDC) emissions are in the range of default emission factors (1,25 ±1 %) defined by IPCC methodology (1997), except for 2002
There is an Intergovernmental Panel on Climate Change (IPCC) methodology for estimating N2O emissions, which relies on emission factors specifying the fraction of N2O emitted to the atmosphere if N-fertilizers, manure or crop residues are applied to soils (Table 1)

Summary

Introduction

With regard to global climate change, soils are of a significant importance as sources for atmospheric trace gas, such as nitrous oxide (N2O). Additions of mineral N-fertilizers, and N from other sources, such as animal manures, crop residues, N2-fixing crops, and sewage sludge (from which ammonium is released by mineralization) to agricultural soils are recognized as major drivers of N2O emissions [5]. There is an Intergovernmental Panel on Climate Change (IPCC) methodology for estimating N2O emissions, which relies on emission factors specifying the fraction of N2O emitted to the atmosphere if N-fertilizers, manure or crop residues are applied to soils (Table 1). Data on crop production systems that are essential for estimating trace gas fluxes include fertilizer use (including animal manure and other organic inputs) and the mass of residues which is ploughed into the soil (in units of N), or the amount produced of the crop(s) whose residues are ploughed in (in units of biomass). Because of shortage of recent data on storage of animal waste in Slovakia all emission balances are evaluated on level business as usual

Investigation object and methodology

Results and discussion

Conclusions