Effects of different nitrogen application amounts on N2O and CO2 emissions from dryland wheat fields in the Loess Plateau of central Gansu
[Objective]This study aimed to investigate the response of soil N2O and CO2 emissions to different nitrogen application rates in dryland wheat fields in the semi-arid region of the Loess Plateau of central Gansu Province.The objective was to understand the emission characteristics and main influencing factors of N2O and CO2 emissions in dryland wheat fields,providing basis for greenhouse gas emission re-duction and nitrogen fertilizer management in dryland wheat fields in this region.[Method]Field position-ing tests and laboratory measurements were used to establish four nitrogen application gradients:CK(no fer-tilization),LN(low nitrogen fertilizer),MN(medium nitrogen fertilizer),and HN(high nitrogen fertilizer).The effects of these application rates on nitrate nitrogen(NO3--N),ammonium nitrogen(NH4+-N),organic carbon(SOC),soil temperature,water content,and N2O and CO2 emissions from the dryland wheat were analyzed.[Result]The results showed that in the 0～10 cm soil layer,the average content of NO3--N in-creased by 21.55%,26.06% and 34.11% in HN,MN and LN treatment compared to the CK treatment.The average content of NH4+-N increased by 21.77%,31.42% and 39.20%,while the average SOC con-tent increased by 20.43%,25.80% and 35.9% .Cumulative N2O emissions increased by 78.63%,130.47% and 217.51%,and cumulative CO2 emissions increased by 5.73%,10.63% and 21.75% .Pear-son correlation analysis revealed positive correlations between the average contents of NO3--N,NH4+-N,SOC,and cumulative emissions of N2O and CO2 under different nitrogen application treatments(P<0.001).Soil temperature exhibited a significant positive correlation with cumulative emissions of N2O and CO2(P<0.05),while soil moisture content showed a significant negative correlation with cumulative emis-sions of N2O(P<0.05),but no significant correlation with cumulative emissions of CO2.[Conclusion]Ni-trogen addition increased N2O and CO2 emissions by increasing the contents of NO3--N,NH4+-N and SOC in the surface soil of dryland wheat fields in the Loess Plateau,representing the primary driving factor for emissions in the region.Soil temperature and moisture content also influenced emissions to some extent.
dry-cropped wheat fieldsnitrogen rateN2OCO2emission fluxesthe Loess Plateau of central Gansu Province
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