Costs and effects of measures to reduce ammonia emissions from dairy cattle and pig production: A comparison of country-specific estimations and model calculations

Understanding the costs of emission abatement measures is essential for devising reduction efforts. It allows to identify cost-effective solutions to achieve target values set by international agreements or national policies. This work aims to summarize and discuss the current knowledge on costs and effects associated with selected ammonia (NH₃) mitigation measures in livestock production through comparison of country-specific and model-estimated values. Often, large differences appear between the results of individual countries, also in comparison with model results that are generally better harmonized between countries. It seems that different system boundaries in cost assessments, but also different geographic and structural conditions create perceived as well as real cost differences, also caused by the variability of individual situations. Our results are robust with respect to identifying feeding strategies as the most cost-effective, but results for other mitigation options do not show any clear trends, thus making it difficult to distinguish further cost-effective solutions. We point out and discuss some key aspects which may affect estimates of national costs, leading to challenges with the interpretation of final results. Our study concludes that further and more consistent assessments (e.g. standardized protocols) are needed to improve the evaluation base for other individual abatement options, including options that are under development.