Abstract. The application of nitrification inhibitors together with ammonium-based fertilizers is proposed as a potent method to decrease nitrous oxide (N2O) emission while promoting yield and nitrogen use efficiency in fertilized agricultural fields. To evaluate the effects of nitrification inhibitors, we conducted year-round measurements of N2O fluxes, yield, aboveground biomass, plant carbon and nitrogen contents, soil inorganic nitrogen and dissolved organic carbon contents and the main environmental factors for urea (U), urea + dicyandiamide (DCD) and urea + 3,4-dimethylpyrazol-phosphate (DMPP) treatments in a wheat-maize rotation field. The cumulative N2O emissions were calculated to be 4.49 ± 0.21, 2.93 ± 0.06 and 2.78 ± 0.16 kg N ha−1 yr−1 for the U, DCD and DMPP treatments, respectively. Therefore, the DCD and DMPP treatments decreased the annual emissions by 35% and 38%, respectively. The variations of soil temperature, moisture and inorganic nitrogen content regulated the seasonal fluctuation of N2O emissions. When the emissions presented clearly temporal variations, year-round and high-frequency measurements should be adopted to estimate annual cumulative emissions and treatment effects. The application of nitrification inhibitors increased the soil inorganic nitrogen and dissolved organic carbon availability and shifted the main soil inorganic nitrogen form from nitrate to ammonium. The annual yield, aboveground biomass and nitrogen uptake by aboveground plants increased by 8.5–9.1%, 8.6–9.7% and 10.9–13.2%, respectively, for the DCD and DMPP treatments compared with the U treatment. The results demonstrate the roles the nitrification inhibitors play in enhancing yield and nitrogen use efficiency and reducing N2O emission from the wheat-maize cropping system.
Effects of nitrification inhibitors (DCD and DMPP) on nitrous oxide emission, crop yield and nitrogen uptake in a wheat–maize cropping system
