Effects of gradually elevated CO2 concentration and reduced nitrogen application on N2O emission in winter wheat field
To investigate the response of N2O emission in wheat field to the gradually elevated CO2 concentration and the reduction of nitrogen fertilizer application,we conducted field experiments using Yangmai 22 as the experimental material.The experiments were carried out on a field equipped with an automatic CO2 concentration control platform formed by Open-Top Chambers(OTC).Under the condition of ambient atmospheric CO2 concentration(AC),a treat-ment of gradually elevated CO2 concentration(EC)was set up,which increased by 40 μmol·mol-1 annually from the winter wheat growing season of 2016-2017,reaching 120 μmol·mol-1 higher than AC in the wheat growing season of 2018-2019.The nitrogen fertilizer treatments were set as a conventional level(N1,25 g·m-2)and a reduced level(N2,15 g·m-2).The N2O fluxes were measured by a static opaque chamber-gas chromatograph method.The results in-dicated that throughout the winter wheat growing period,the changes of N2O emission from winter wheat field were rel-atively consistent for all treatments with an overall fluctuating downward trend.No significant effect of EC treatment on N2O emission was observed during the winter wheat growing seasons.While the N2 treatment significantly reduced the cumulative N2O emission by 45.2％compared with the N1 treatment(P=0.004)under the AC,which was not signifi-cant under EC treatment.The impact of nitrogen reduction on N2O emission was evident during winter wheat stage from booting to milking.Under the combined effect of gradually elevated CO2 concentration and reduced nitrogen fertilizer application,the latter was the main factor affecting N2O emission in winter wheat field.
万方数据
