Greenhouse Gas Emission Characteristics Of Spring Wheat Fields Under Different N-fertilized Levels On The Loess Plateau Of Central Gansu Province

In order to explore the effects of different nitrogen levels on greenhouse gas CO₂ and N₂O emissions,through long-term experiment in dry farmland of the Loess Plateau of central Gansu Province,with 0kg/hm²,52.5 kg/hm²,105.0 kg/hm²,157.5 kg/hm² and 210.0 kg/hm²nitrogen applications as the research object.Meanwhile,adopting Gas chromatograph and EGM-4 to analyze the N₂O and CO₂ flux change law among different N-fertilized levels in the whole growth period.Moreover,the temperature and moisture of soil in the same period are measured order to further explore the relationship between the two gas emission and environmental factors.The following results are obtained:?1?In the growth period,the N₂O emission was added with nitrogen fertilizer,on the contrary,CO₂ emission was reduced.For N₂O emission,N5 treatment is the highest,N1is the lowest.For CO₂ emission,N1 treatment is the highest,N5 is the lowest.?2?In the growth period,the emission of N₂O and CO₂ appeared seasonal change,and the trend of change was consistent among different treatments.N₂O emission flux was gentle before the emergence stage,and appeared higher emission trend in the jointing stage and pustulation stage,where the emission peak in the pustulation stage was higher than that of jointing stage;and the CO₂ emission flux was gentle before the tillering stage.It appeared higher emission trend in the tillering stage,and the highest emission peak in the jointing stage,and lower and gentle trend after florescence stage.?3?The emission of N₂O and CO₂ were influenced by soil temperature and soil moisture content.With the soil temperature changes higher,the emission of N₂O and CO₂ changed higher.The average flux of N₂O is positively correlated to soil temperature,correlation coefficient is 0.479,0.519 and 0.394,respectively.The correlation coefficient of CO₂ is 0.427,0.419 and 0.483,respectively;0⁵cm and 10³0cm soil moisture content restrain N₂O emission,correlation coefficient is-0.173 and-0.367,respectively;5¹0cm soil moisture content improve N₂O emission;with soil water content changes higher,the emission of CO₂changed lower,correlation coefficient is-0.131,-0.125 and-0.385,respectively.?4?With applied N-fertilizer changes higher,the GWP of N₂O changed higher and the GWP of CO₂ changed lower.The global warming potential change range of N₂O and CO₂emission on dry farmland is obvious among different N-fertilized levels,variation range is3731.768⁴339.891 kgCO₂-e/hm².