Life cycle assessment (LCA) of different fertilizer product types

Abstract

Appropriate use of fertilizer in crop production to limit the environmental impact is essential for sustainable agriculture. While much is known about the environmental impact of fertilizer production only a limited amount of data is available covering the whole fertilizer supply chain. Up to now no comparison was done on the environmental impact of different fertilizer types (i.e., complex fertilizer, bulk blend fertilizer and single nutrient fertilizer). A cradle-to-field life cycle assessment (LCA) for the fertilizer supply chain in Germany, from extraction of raw materials, via fertilizer production, transportation and storage until final application in the field was carried out. Two different complex fertilizers were compared with single nutrient fertilizers (containing only one nutrient) and bulk blend fertilizers (containing more than one nutrient as a dry mixture). The five most relevant impact categories (i.e., climate change, acidification, eutrophication, fossil fuel depletion and resource depletion) were selected to cover different environmental impacts. Additionally, a scenario analysis was carried out focusing on nitrous oxide (N2O) emissions, as new catalytic reduction techniques for the manufacturing of nitrogen (N) containing fertilizers are available that can lead to drastic reductions of N2O emissions.Production of fertilizers causes high values in the impact categories climate change, fossil fuel depletion and acidification, whereas resource depletion is dominant for production and transportation. For the impact category eutrophication, the application of fertilizer is the most important factor.For a fertilizer strategy with low phosphorus application rate, a bulk blend or single nutrient fertilizer with calcium ammonium nitrate is the most sustainable choice, while for a fertilizer strategy with a balanced nutrient formula, a bulk blend or single nutrient fertilizer with calcium ammonium nitrate or a standard complex fertilizer are sustainable options. Scenario calculations with reduced N2O emission during the production process reveals that this reduction technique is not relevant for urea based fertilizers leading to the conclusion that products containing urea need different emission reduction techniques to keep up with the environmental improvements of other nitrogen fertilizers.With an optimized fertilization strategy the environmental burden can be reduced up to 15%. As nitrogen application rates strongly affect the LCA results it is essential that the right amounts of N are used and that for N fertilizer production the best available technique should be installed. Furthermore, a careful consideration concerning the fertilizer product type should be part of every LCA of food and agricultural products, as this has a great impact on LCA results.