Eco-innovations in the German fertilizer supply chain: Impact on the carbon footprint of fertilizers

The aim of this paper is to analyse to what extent the existing eco-innovations in the German fertilizer domain might reduce the fertilizer carbon footprint without compromising on crop productivity. The continuously growing demand for agricultural products will require a further increase in agricultural production mostly achieved with additional external inputs (fossil energy, pesticides, irrigation water and fertilizers). Fertilizer in general and nitrogen fertilizers in particular are major factors for yield increases in crop production. On the other hand, emissions of greenhouse gases play a dominant role in the debate on the environmental burden of fertilizers. Typical mineral fertilizers were compared with so-called stabilized nitrogen fertilizers and secondary raw material fertilizers in this study. Additionally, an effect of the combination of irrigation with fertilization (i.e. fertigation) was investigated. With an adopted life cycle assessment approach focusing on CO2 and N2O emission, the carbon footprints of the different fertilizer options were considered. The calculations showed that especially the use of stabilized nitrogen fertilizer reduced the fertilization-related carbon footprint up to 13%. However, because of higher costs or incomplete supply chain relationships, adoption of these innovations is expected to be rather limited in the near future. Fertilizers made from secondary raw materials resulted in similar carbon footprints as mineral ones, but they can help to close nutrient cycles and use by-products of other production processes.