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

Summary

This paper presents a 'road test' evaluation of five North American greenhouse gas offset protocols (ACR1, ACR2, VCS, CAR, Alberta) applied to nitrogen management activities in dryland wheat systems of the inland Pacific Northwest. Only two protocols (ACR2 and VCS) were deemed suitable, producing identical quantification methodologies and emission reduction estimates. The findings suggest that current offset payment levels from N2O reductions alone are unlikely to motivate farmers to adopt variable rate or split nitrogen application strategies, raising questions about the practical effectiveness of these protocols in driving agricultural climate mitigation.

UK applicability

While this study focuses on Pacific Northwest dryland wheat systems, the protocol comparison methodology and findings regarding offset payment adequacy are relevant to UK policymakers and carbon market developers designing schemes for cereals production. The conclusion that current N2O offset valuations are insufficient to incentivise adoption could inform UK agricultural carbon credit design.

Key measures

Nitrous oxide (N2O) emission reductions (Mg CO2e ha⁻¹); estimated offset payments (USD ha⁻¹) at carbon prices of $5, $10, and $50 per metric tonne CO2 equivalent; consistency and applicability of five agricultural offset protocols

Outcomes reported

The study evaluated five agricultural nitrogen management offset protocols and compared their quantification methodologies for nitrous oxide emission reductions under dryland wheat cropping systems in the Pacific Northwest. Sample projects reducing nitrogen fertilizer application via variable rate or split application management generated N2O emission reductions ranging from 0.07 to 0.26 Mg CO2e ha⁻¹, with associated offset payments of $0.35 to $13.0 ha⁻¹ across carbon price scenarios.

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