Using a Nitrification Inhibitor in Maintaining Wheat Grain Protein Under Elevated CO2.

Atmospheric carbon dioxide (CO₂) concentration has been increasing since the industrial revolution. Elevated CO₂ generally reduces wheat grain protein but increases nitrous oxide (N₂O) emission from cropping systems. While the suppression of nitrate (NO₃^–) photoassimilation under elevated [CO₂] may explain the reduction of protein, the manipulation of the form of soil mineral N source (NO₃^– vs. ammonium (NH₄⁺)) has the potential of improving grain protein. The aims of this research were to investigate whether N management (the use of nitrification inhibitors) can (i) improve grain protein concentration and fertiliser N recovery under future CO₂ concentration, and (ii) counteract the potential positive effect of elevated CO₂ on N₂O emission. The research was undertaken at the free-air CO₂ enrichment (FACE) in Australia. Preliminary results suggested that the nitrification inhibitor has the potential to reduce N₂O emission under elevated CO₂ and maintain grain protein. The findings provide implications for food security, grain industry and the environment.