Modelling carbon dioxide emissions from agricultural soils in Canada

Agricultural soils are a leading source of atmospheric greenhouse gas (GHG) emissions and are major contributors to global climate change. Carbon dioxide (CO₂) makes up 20% of the total GHG emitted from agricultural soil. Therefore, an evaluation of CO₂ emissions from agricultural soil is necessary in order to make mitigation strategies for environmental efficiency and economic planning possible. However, quantification of CO₂ emissions through experimental methods is constrained due to the large time and labour requirements for analysis. Therefore, a modelling approach is needed to achieve this objective. In this paper, the DeNitrification-DeComposition (DNDC), a process-based model, was modified to predict CO₂ emissions for Canada from regional conditions. The modified DNDC model was applied at three experimental sites in the province of Saskatchewan. The results indicate that the simulations of the modified DNDC model are in good agreement with observations. The agricultural management of fertilization and irrigation were evaluated using scenario analysis. The simulated total annual CO₂ flux changed on average by ±13% and ±1% following a ±50% variance of the total amount of N applied by fertilising and the total amount of water through irrigation applications, respectively. Therefore, careful management of irrigation and applications of fertiliser can help to reduce CO₂ emissions from the agricultural sector. - Highlights: • DNDC model is modified for the Canadian soil and weather conditions. • Modified DNDC model is validated against measured data in three Canadian sites. • Parameterisation of modified DNDC model with snowmelt routine is made. • Effect of irrigation and fertiliser applications on CO₂ emissions is identified.