Exploring systems responses to mitigation of GHG in UK dairy farms

A variety of options exist for mitigation of greenhouse gas (GHG) emissions from agriculture. This paper discusses the use of the SIMSDAIRY modelling framework to analyse the whole-systems response to different methods, acting singly or in combination, to mitigate GHG emissions from a typical dairy farm in the UK. These methods comprise farm management changes, new technologies and/or plant and/or animal new functional traits focused on mitigating GHG. Different functional units were used in order to ensure that the different aspects of the farm performance were analyzed in the most relevant way (e.g. concentration of NO3− in leachate or kg GHG emitted per unit of milk). Examples of the methods that were tested and discussed are some relating fertilization, diet, systematic and genetic changes in the system. We conclude that the effectiveness of the combined GHG mitigation methods cannot be assessed simply by adding the effectiveness of each method applied singly. Effective GHG mitigation methods may in some cases increase emissions of other forms of pollution and have very different impact on farm profitability. This study also evidences the importance of selecting the right unit of reference to measure efficacy to reduce GHG emissions and highlights the importance to integrate this type of study with socio-economic studies in order to assess the full potential of these mitigation methods.