Nitrification inhibitor DMPSA mitigated N2O emission and promoted NO sink in rainfed wheat

Fertilized cropping systems are important sources of nitrous oxide (N₂O) and nitric oxide (NO) to the atmosphere, and biotic and abiotic processes control the production and consumption of these gases in the soil. In fact, the inhibition of nitrification after application of urea or an ammonium-based fertilizer to agricultural soils has resulted in an efficient strategy to mitigate both N₂O and NO in aerated agricultural soils. Therefore, the NO and N₂O mitigation capacity of a novel nitrification inhibitor (NI), 2-(3,4-dimethyl-1H-pyrazol-1-yl) succinic acid isomeric mixture (DMPSA), has been studied in a winter wheat crop. A high temporal resolution of fluxes of NO and NO₂, obtained by using automatic chambers for urea (U) and urea with DMPSA, allowed a better understanding of the temporal net emissions of these gases under field conditions. Seventy-five days after fertilization, the effective reduction of nitrification by DMPSA significantly decreased the production of NO with respect to the treatment without it, giving net consumption of NO in the soil (-61.72 g-N ha^-1) for U + DMPSA in comparison to net production (227.44 g-N ha^-1) for U. The explanation of NO deposition after NI application, due to biotic and abiotic processes in the soil-plant system, supposes a challenge that needs to be studied in the future. In the case of N₂O, the addition of DMPSA significantly mitigated the emissions of this gas by 71%, though the total N₂O emissions in both fertilized treatments were significantly greater than those of the control (43.69 g-N ha^-1). Regarding the fertilized treatments, no significant effect of DMPSA in comparison to urea alone was observed on grain yield nor bread-making wheat quality. To sum up, we got a significant reduction of N₂O and NO with the addition of DMPSA, without a loss in yield and quality parameters in wheat.