Improving the accounting of field emissions in the carbon footprint of agricultural products: a comparison of default IPCC methods with readily available medium-effort modeling approaches

Abstract

Purpose The estimations of greenhouse gas (GHG) field emissions from fertilization and soil carbon changes are challenges associated with calculating the carbon footprint (CFP) of agricultural products. At the regional level, the IPCC Guidelines for National Greenhouse Gas Inventories (2006a) Tier 1 approach, based on default emission factors, insufficiently accounts for emission variability resulting from pedo-climatic conditions or management practices. However, Tier 2 and 3 approaches are usually considered too complex to be practicable. In this paper, we discuss different readily available medium-effort methods to improve the accuracy of GHG emission estimates. Methods We present four case studies-two wheat crops in Germany and two peach orchards in Italy-to test the performance of Tier 1, 2, and 3 methodologies and compare the estimated results with available field measurements. The methodologies selected at Tier 2 and Tier 3 level are characterized by simple implementation and data collection, for which only a medium level of effort for stakeholders is required. The Tier 2 method consists of calculating direct and indirect N 2 O, emissions from fertilization with a multivariate empirical model which accounts for pedo-climatic and crop management conditions. The Tier 3 method entails simulation of soil carbon stock change using the Rothamsted carbon model. Results and discussion Relevant differences were found among the tested methodologies: in all case studies, the Tier 1 approach exceeded the Tier 2 estimations for fertilizer-induced emissions (up to +50 %) and the measurements. Using this higher Tier approach reduced the estimated CFP calculation of annual crops by 4 and 21 % and that of the perennial crop by 7 %. Removals related to positive soil carbon change calculated using the Tier 1 approach also exceeded the Tier 3 calculations for the studied annual crops (up to +90 %) but considerably underrated the Tier 3 estimations and measurements for perennial crops (−75 %). In this case, the impact of the selected Tier method on the final CFP results was even more relevant: an increase of 194 and 88 % for the studied annual crops and a decrease of 67 % for the perennial crop case study. Conclusions The use of higher Tiers for the estimation of land-based emissions is strongly recommended to improve the accuracy of the CFP results. The suggested mediumeffort methods tested in this study represent a good compromise between complexity reduction and accuracy improvement and can be considered reliable for the assessment of GHG mitigation potentials.

Assessment of N2O emissions from rapeseed cultivation in Poland by various approaches

“…The studies performed for ecodistricts in Canada indicated that the DNDC model overestimated N 2 O emissions in comparison to Tier 2 estimations (Smith et al, 2010). Peter et al (2016) found out that for winter wheat cultivation in Germany on Stagnic Cambisol (HAC) and Luvisol (HAC) soil type the N 2 O emissions calculated with Tier 2 were lower than with the Tier 1 approach. In addition, they stated that the calculation of N 2 O emissions for annual crops with a higher Tier approach is particularly important when fertilizer-induced field emission is being estimated.…”

“…Since that time, the original model has been used intensively by many researchers and adopted to different scenarios and ecosystems (Gilhespy et al, 2014; 401 peer reviewed publication in WEB of Science, 2 June 2016). It has been applied at field scale (Abdalla et al, 2009, Beheydt et al, 2007Peter et al, 2016), country (Li et al, 2001;Lugato et al, 2010;Perlman et al, 2013;Smith et al, 2010) and regional level (Leip et al, 2008). In addition, the DNDC model was adopted to set sustainability criteria for biofuels production in Europe (Directive 2009/28/EC).…”

“…There are many studies were N 2 O field emissions were compared with Tier 1 and 3 methods (Abdalla et al, 2009;Beheydt et al, 2007;Li et al, 2001;Lugato et al, 2010). However, there are only a few studies were differences in N 2 O emissions between all three Tiers are presented (Peter et al, 2016;Smith et al, 2010). All the studies present the influence of different climate, soil and management practices on N 2 O emissions.…”

A Regional Analysis of the Life Cycle Environmental and Economic Tradeoffs of Different Economic Growth Paths

“…The "Cumulative Energy Demand" method was used to estimate the life cycle energy associated with each industry [67]. The "IPCC 2007 GWP 20a" method was utilized to calculate the life cycle GHG emissions of each industry [68]. The "ReCiPe Midpoint" hierarchist version was used to quantify freshwater and marine eutrophication potentials [69].…”

Global warming potential and sustainable management of three land uses in Varanasi

“…There are several studies reporting on GHG emissions from forest, agriculture and landfill using various estimation techniques including default emission values (Peter et al, 2014). However, information on-site-level direct measurements of soil borne fluxes are meagre.…”