Abstract:In order to reveal the effects of irrigation water amount on soil CO2, N2O emissions and spring maize growth under groundwater and brackish water irrigation, two kinds of irrigation water salinity (1.1g/L and 5.0g/L) and three kinds of irrigation water amounts (210mm, 255mm and 300mm) were set up in Hetao Irrigation District from April to September, 2019. The results showed that compared with groundwater (1.1g/L) irrigation, soil N2O emissions were increased by 19.86%~44.21% under brackish water (5.0g/L) irrigation, but irrigation water salinity did not affect soil CO2 emissions and global warming potential (GWP). Under the same irrigation water salinity conditions, cumulative CO2 emissions, cumulative N2O emissions and GWP were the largest when the irrigation water amount was 300mm, and the cumulative CO2 emissions, cumulative N2O emissions and GWP were not significantly affected by the irrigation water amount of 210mm and 255mm. The results of correlation analysis showed that soil moisture and inorganic nitrogen content were important factors affecting soil CO2 and N2O emissions, and irrigation water salinity promoted soil N2O emissions by promoting soil nitrification. The yield of spring maize under brackish water (5.0g/L) irrigation was 30.88%~37.32% lower than that under groundwater (1.1g/L) irrigation. The yield of spring maize was increased with the increase of irrigation water amount, but there was no significant difference under the irrigation water amount of 255mm and 300mm. Under the condition of groundwater (1.1g/L) and brackish water (5.0g/L) irrigation, when the irrigation water amount was 255mm, the soil salt accumulation was smaller, while the higher spring maize yield was obtained, and the cumulative CO2 and N2O emissions and GWP were relatively small, which was the suitable irrigation quota for Hetao Irrigation District.
