Regional nitrogen resilience as distance-to-target approach in LCA of crop production systems

Agricultural production systems are highly dependent on nitrogen (N) inputs. According to assessments following the concept of Planetary Boundaries (PB), global limits for N cycles are already exceeded. However, regional thresholds and resiliencies may vary as N compounds have implications on different spatial scales, for instance, eutrophication or acidification on the regional level. Regional N management activities may influence these environmental impacts. Thus, regional N resiliencies must be considered when assessing agricultural systems with Life Cycle Assessment (LCA). This paper provides an approach for integrating regional N resilience as distance-to-target in assessing crop production systems. Therefore, regional carrying-capacity based normalisation references were developed integrating N-related thresholds for agricultural intervention based on the Life Cycle Impact Assessment (LCIA) framework. In addition, regional background interventions of non-crop production sectors were taken into account to comprehensively assess the regional environmental performances of cropping systems. Moreover, regionalisation effects were assessed applying spatially differentiated characterisation factors. The approach is applied to a case study for two different NUTS-3 regions in Germany, including different N management scenarios. The results showed a high influence of the integrated background intervention and regional characterisation on the environmental performances of the cropping systems. N resiliencies were exceeded for all regions, when assuming high yield scenarios, for both eutrophication and acidification impacts. Finally, we present the first proof for application as additional decision support for regional stakeholders regarding N management strategies. For further development and improvement, future research should include investigations of different NUTS-3 regions, N management scenarios and emission reduction levels for background interventions.