Nitrous oxide emissions and ammonia volatilisation in a field experiment with different organic and inorganic fertilisers with biochar combinations

Agriculture is contributing majorly to anthropogenic greenhouse gas emissions and pollution. The application of nitrogen fertilizers increases N₂O emissions and NH₃ volatilisation. Nitrous oxide (N₂O) is a highly potent greenhouse gas and ammonia (NH₃) can re-react with soil and forms N₂O or can lead to other environmental issues in the surrounding. Further, to keep economic (fertiliser prizes drastically increased due to the energy crisis) and ecological (Haber Bosch process is very energy intense and still based on fossil fuels) costs for fertiliser low, a high fertilizer use efficiency is worthwhile. Therefore, advances in agricultural practices reducing atmospheric N-losses are highly relevant in order to mitigate global warming and related environmental issues. Biochar can reduce N₂O emissions and NH₃ volatilisation by influencing various soil properties. However, this depends on pedoclimatic conditions, the applied biochar, and other agricultural practises. To refine biochar’s use to mitigate atmospheric N-losses more data for different soils and fertilizers are needed, especially from experiments coming close to common agricultural settings. In a field experiment we cultivated corn (Zea mays) with different organic (external organic matter, EOM) and inorganic fertilizers with and without biochar combinations. The original soil was loamy, low in organic carbon and slightly acidic. Our results are showing significant and substantial reductions in N₂O emissions and NH₃ volatilisation within the first weeks after fertiliser application. This pattern was especially observed for synthetic fertiliser. We suggest that biochar is a suitable amendment for fertilisation, especially for highly productive agroecosystems where high amounts of fertiliser are needed, to reduce environmental impact and increase fertiliser use efficiency.