Effects of water and nitrogen management on N2O emissions and NH3 volatilization from a vineyard in North China

Agricultural soils are a major source of anthropogenic N2O emissions and NH3 volatilization because of the large input of nitrogen (N) via fertilizers. Chinese vineyards commonly receive excessive water and N applications, but the response of gaseous losses to these management practices are not well documented. In this study, a field experiment was conducted to measure N2O emissions and NH3 volatilization from a typical table grape (Vitis vinifera L.) vineyard in North China. Three water and N regulation management strategies were applied and compared with the local farmer's traditional water and N management (TWN, traditional flooding irrigation and traditional N application rate, flood irrigation was carried out after the fertilizers furrowing-applied) as a control, mobile water and fertilization (MWF, 62% tradition N application rate and 60% traditional irrigation amount, flood irrigation was carried out after the dissolved fertilizers injected into rhizosphere (20 cm deep) with a liquid-jet gun), optimum water and N (OWN, 69% tradition N application rate and 70% traditional irrigation amount, the fertilization and irrigation method were the same as those in the TWN treatment) and optimum water and N combined with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) (OWN+DMPP, 1% DMPP was applied on the basis of the OWN treatment). The MWF, OWN and OWN+DMPP treatments significantly (P < 0.05) reduced the mean N2O fluxes with little effect on the NH3 volatilization rate. However, over the whole grape-growing season, the cumulative N2O total and yield-scaled N2O emissions in the three treatment groups were significantly reduced by 27.44–29.23% and 34.66–43.71%, respectively. In addition, the cumulative NH3 and yield-scaled NH3 volatilization were reduced by 4.13–6.61% and 21.81–26.15%, respectively. Notably, N2O emissions were significantly positively correlated with soil temperature, WFPS and NH4-N nitrogen contents, suggesting that these are the most important factors controlling N2O emissions in table grape plantations. Additionally, NH3 volatilization was closely related with soil temperature. Comprehensive evaluation showed that, based on the traditional water and N application rate, 38% N reduction combined with mobile water and fertilizer (MWF) effectively reduced the risk of N gaseous losses to the environment and saves irrigation water while maintaining grape yield.