The use of mineral fertilizer is essential for sustainable agriculture. Mineral fertilizers are applied to balance the gap between the nutrients required for optimal crop development and the nutrients supplied by the soil and by available organic sources.

As all human activities, crop production and in particular the use of mineral fertilizer has an “environmental footprint”. With regards to N fertilizers this is mainly related to eutrophication and acidification of ecosystems, and the release of greenhouse gases (GHG). This paper investigates the GHG emissions (“carbon footprint”) of crop production in general and the role of mineral nitrogen fertilizers in particular.

Production and use of mineral and organic N fertilizer contributes significantly to the global GHG emissions, but the major agricultural contribution to GHG emissions on the global scale is the expansion of agricultural land into forests and wetlands.

This study compares the carbon footprint of crop production with different nitrogen fertilizer inputs based on life-cycle assessment (LCA) principles. This means it includes all on-farm activities to produce wheat grain, the production and supply of seeds, pesticides, machinery, and fertilizers as well as the extraction and processing of any raw materials needed.

The study reveals that intensive crop production aiming at economic optimum N supply helps mitigating GHG emissions by preserving natural land from being converted into cropland.