The outputs of LCI are then grouped into selected impact categories using science-based conversion factors. The selection of impact categories e a part of the initial goal and scope definition phase e is the following step. Three impact categories were chosen to be considered in this study: Respiratory inorganics (RI), Global warming (GW) and Non-renewable energy (NRE). Characterization factors play a prominent role in LCIA because they convert different inventory inputs into directly comparable impact indicators. The characterization factors for background data e data related to production of input materials e used in this study were adapted from SimaPro® software (Anonymous, 2011). On-farm emissions were calculated based on IPCC guidelines (IPCC, 2006). Characterization factors are summarized in Table 2.