Influence of the Nitrification Inhibitor Dmpsa on Wheat Yield, Grain Quality and Soil Greenhouse Gases Emissions Under Humid Mediterranean Conditions.

Wheat is among the three most cultivated cereals in the world, and in Spain the highest yield of wheat crop is given under humid Mediterranean conditions. In order to enhance crop yield, the management is based on the addition of nitrogen (N) fertilizers. Nevertheless, its application can increase nitrous oxide (N₂O) emissions, being a strong greenhouse gas (GHG).  Regarding GHG, soil processes can also produce or consume carbon dioxide (CO₂) and methane (CH₄). In order to decrease N losses induced by fertilization and increase nitrogen use efficiency, nitrification inhibitors (NI) have been developed. The fact that the application of a NI enhances N use efficiency would allow an increase in the grain N concentration of wheat plants leading to an increase in grain quality due to a higher accumulation of reserve proteins, gliadins and glutenins.

We present a wheat field-experiment aimed at evaluating the influence of the new nitrification inhibitor 3,4-dimethylpyrazol succinate (DMPSA) on grain yield, grain quality and GHG emissions. Fertilizer rate with and without DMPSA was 180 kg N ha^-1 applied as ammonium sulfate (AS) to wheat splitted in two (60+120 kg N ha^-1) amendments. Treatments with a non-splitted single application of AS with DMPSA (180 kg N ha-1) and an unfertilized treatment (0 kg N ha-1) were also included. Under our edaphoclimatic conditons, the application of DMPSA in a standard twice-splited fertilization management maintained yield and its components, and also grain quality to the levels of the control without inhibitor, reducing N₂O emissions up to the unfertilized levels. A single application of DMPSA also reduced N₂O emissions but decreased grain yield and quality.

Acknowledgements: This project was funded by the Spanish Government (RTA2013-00057-CO5-02 and AGL2012-37815-C05-02), by the Basque Government (IT-526-10) and by EuroChem Agro Iberia S.L.-UPV/EHU 2013.0001. Ximena Huérfano held a grant from the Ministry of Economy and Competitiveness of the Spanish Government.