Assessing the environmental benefit of a new fertilizer based on activated biochar applied to cereal crops

This study analyzes the environmental benefits that a nitrogen fertilizer based on activated biochar has in comparison to other traditional fertilizers (urea, ammonium nitrate (AN), ammonium sulfate (AS) and di-ammonium phosphate (DAP)). With this aim, activated biochar was generated from residual biomass (barley straw) through physical activation and the resulting biochar was combined with mineral fertilizer to synthethise the fertilizer. This new product was subjected to environmental assessment by means of two different approaches, Life Cycle Assessment (LCA) and nitrogen footprint procedure, both of which considered standard conditions typical of Mediterranean climate and wheat and corn as the fertilized crops. Emission factors of traditional fertilizers were obtained from internally developed models, which were in turn based on real data from literature. As for emission factors of the new product, they were calculated basing on experimental results. Fertilizer impacts in terms of acidification, eutrophication and climate change were estimated, thus revealing a great performance of activated biochar over other fertilizers in terms of reactive nitrogen (Nr), reaching a maximum saving rate of 63% in the amount of Nr released by volatilization and leaching. In addition, this work offers a methodology for environmental analysis of fertilizers and provides useful quantitative indicators for the environmental benefit and the saving of reactive nitrogen, which could contribute to the development of new commercial low N-emissions fertilizers.