Impact of management strategies on the global warming potential at the cropping system level

• Published in: The Science of the total environment 2014-08, Vol.490, p.921-933
• Main Authors: Goglio, Pietro, Grant, Brian B., Smith, Ward N., Desjardins, Raymond L., Worth, Devon E., Zentner, Robert, Malhi, Sukhdev S.
• Format: Article
• Language: English
• Subjects: Agriculture - methods; Agronomy. Soil science and plant productions; Air pollution; Air Pollution - analysis; Air Pollution - prevention & control; Air Pollution - statistics & numerical data; Applied sciences; Biological and medical sciences; Climate Change; Crop management; Cropping systems; Crops, Agricultural - growth & development; DNDC; Energy demand; Estimating; Exact sciences and technology; Fertilizers - analysis; Fertilizers - statistics & numerical data; Fertilizing; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; Global environmental pollution; Global Warming; Greenhouse Effect; GWP; LCA; Management; Nitrous oxides; Pollution; Residues; Strategy
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2014.05.070

Estimating the greenhouse gas (GHG) emissions from agricultural systems is important in order to assess the impact of agriculture on climate change. In this study experimental data supplemented with results from a biophysical model (DNDC) were combined with life cycle assessment (LCA) to investigate the impact of management strategies on global warming potential of long-term cropping systems at two locations (Breton and Ellerslie) in Alberta, Canada. The aim was to estimate the difference in global warming potential (GWP) of cropping systems due to N fertilizer reduction and residue removal. Reducing the nitrogen fertilizer rate from 75 to 50kgNha−1 decreased on average the emissions of N2O by 39%, NO by 59% and ammonia volatilisation by 57%. No clear trend for soil CO2 emissions was determined among cropping systems. When evaluated on a per hectare basis, cropping systems with residue removal required 6% more energy and had a little change in GWP. Conversely, when evaluated on the basis of gigajoules of harvestable biomass, residue removal resulted in 28% less energy requirement and 33% lower GWP. Reducing nitrogen fertilizer rate resulted in 18% less GWP on average for both functional units at Breton and 39% less GWP at Ellerslie. Nitrous oxide emissions contributed on average 67% to the overall GWP per ha. This study demonstrated that small changes in N fertilizer have a minimal impact on the productivity of the cropping systems but can still have a substantial environmental impact. •LCA was combined with DNDC model to estimate the GWP of a cropping system.•N2O, NO and NH3 flux increased by 39% under the higher fertilizer rate.•A change from 75 to 50kgNha−1 reduced the GWP per ha and GJ basis by 18%.•N2O emissions contributed 67% to the overall GWP of the cropping system.•Small changes in N fertilizer can have a substantial environmental impact.