Comparison of Greenhouse Gas Offset Quantification Protocols for Nitrogen Management in Dryland Wheat Cropping Systems of the Pacific Northwest

Abstract

In the carbon market, greenhouse gas (GHG) offset protocols need to ensure that emission reductions are of high quality, quantifiable, and real. Lack of consistency across protocols for quantifying emission reductions compromise the credibility of offsets generated. Thus, protocol quantification methodologies need to be periodically reviewed to ensure emission offsets are credited accurately and updated to support practical climate policy solutions. Current GHG emission offset credits generated by agricultural nitrogen (N) management activities are based on reducing the annual N fertilizer application rate for a given crop without reducing yield. We performed a "road test" of agricultural N management protocols to evaluate differences among protocol components and quantify nitrous oxide (N 2 O) emission reductions under sample projects relevant to N management in dryland, wheat-based cropping systems of the inland Pacific Northwest (iPNW). We evaluated five agricultural N management offset protocols applicable to North America: two methodologies of American Carbon Registry (ACR1 and ACR2), Verified Carbon Standard (VCS), Climate Action Reserve (CAR), and Alberta Offset Credit System (Alberta). We found that only two protocols, ACR2 and VCS, were suitable for this study, in which four sample projects were developed representing feasible N fertilizer rate reduction activities. The ACR2 and VCS protocols had identical baseline and project emission quantification methodologies resulting in identical emission reduction values. Reducing N fertilizer application rate by switching to variable rate N (sample projects 1-3) or split N application (sample project 4) management resulted in a N 2 O emission reduction ranging from 0.07 to 0.16, and 0.26 Mg CO 2 e ha −1 , respectively. Across the range of C prices considered ($5, $10, and $50 per metric ton of CO 2 equivalent), we concluded that the N 2 O emission offset payment alone ($0.35-$13.0 ha −1 ) was unlikely to encourage a change in fertilizer N management; however, the fertilizer cost savings from adopting variable or split N management would incentivize Brown et al.Nitrogen Management for GHG Offsets adopting these practices. Therefore, the monetary incentive of adopting agricultural N management BMPs for reducing N 2 O emission should be tied to other co-benefits and existing conservation programs to encourage N rate reductions that do not limit yield, crop quality, or economic stability.

Confronting Climate Change Challenges to Dryland Cereal Production: A Call for Collaborative, Transdisciplinary Research, and Producer Engagement

“…The magnitude of N 2 O soil emissions, and related emissions from agricultural nitrate runoff in surface waters (e.g., Turner et al, 2015) presents opportunities for innovative agricultural practices (e.g., fertilizers with nitrification inhibitors and precision application of fertilizers) to reduce GHG emissions and benefit producers in the short term. Although the mitigation of agricultural GHG emissions generally does not provide a monetized return to farmers and is not currently encouraged by direct public policy incentives or regulations (Brown et al, 2017); effective adaptation practices could achieve "win-win" benefits in which cropping system profitability is increased through more efficient use of applied nitrogen, resulting in both improved farm productivity and reduced N 2 O emissions (Millar et al, 2010). Roughly 1% of the nitrogen applied results in N 2 O production, but emissions are variable, influenced by climate, soil organic carbon (SOC), soil texture, soil drainage, soil pH, crop management practices, soil nutrient conditions, and soil O 2 status (IFA/FAO, 2001;McSwiney and Robertson, 2005;Del Grosso et al, 2010;Lehuger et al, 2011;Chi et al, 2016Chi et al, , 2017Waldo et al, 2016).…”

“…It aimed to improve knowledge of the production systems, identify opportunities to improve their efficiency and sustainability, promote farmer participation, provide decision support tools, educate producers and citizens at all levels. The conceptual framework, outputs and outcomes of the REACCH project can be accessed through its web site: https://www.reacchpna.org, and in publications, including some appearing in this special issue of Frontiers in Ecology and Evolution: (1) Develop a theoretical framework integrating cropping system, economic and climate modeling (Abatzoglou et al, 2014;Antle et al, 2017;Stöckle et al, 2017), (2) Monitor greenhouse gas (GHG) emissions and nitrogen and carbon dynamics in the production systems (Chi et al, , 2017Waldo et al, 2016;Kostyanovsky et al, 2017), (3) Compare current and aspirational production systems for productivity and GHG emission potential under current and projected climate Brown et al, 2017;Maaz T. M. et al, 2017;Stöckle et al, 2017), (4) Address the environmental, social, and economic factors influencing agriculture and technology adoption (Antle et al, 2017;Karimi et al, 2017;Kaur et al, 2017), (5) Anticipate climate change related changes in crop protection requirements (Davis et al, 2015a(Davis et al, ,b, 2017Eigenbrode et al, 2015;Foote et al, 2017), (6) Work closely with producers to develop and guide project activities (Kruger and Yorgey, 2017;Yorgey et al, 2017), (7) Educate students from elementary through graduate levels to prepare coming generations for challenges related to climate change in agriculture (White et al, 2014), (8) Ensure data from the project and related projects are managed to facilitate detecting trends and interdisciplinary collaboration (Flathers et al, 2017), and (9) Coordinate all these activities under an integrated, transdisciplinary framework Morton et al, 2015).…”