Study On Mechanism And Factors Of Nitrous Oxides In North China Plain

Agricultural soils represent the major source of the atmospheric greenhouse gas nitrous oxide （N₂O） and the microbial nitrification and denitrification are among the most important N₂O source processes. We investigated Soil Physical and Chemical Properties （soil texture, soil moisture, soil temperature, soil aeration, soil pH etc.）, nitrogen sources and the supply of nitrogen, the availability of Soil organic carbon, C/N etc. regulation of the N₂O emission in a series of experiment. In this study, we systemic research the effects of soil moisture and water adjustment, acidic condition, the content of Glucose, the availability of carbon sources on N₂O emissions, investigate N₂O production mechanisms and influencing factors in North China Plain,to seek providing theoretical supports for seeking the effective way of inducing N₂O emissions suitable for North China Plain with laboratory static incubation method.The main results and conclusions are as follow:（1）Soil N₂O emission in North China Plain is controlled by regulation of soil moisture, we regulation of soil moisture with Water-Hold-Capacity, soil N₂O emission greater than with Water-filled pore space N₂O emission appears in WFPS70% water content,the peak reached 588.85μg N/kg/d.We regulation of soil moisture with Water-Hold-Capacity,Soil CO₂ emissions is higher than Water-filled pore space.（2）Microbial denitrification is the dominant contributor for N₂O production in Norway. The application of NH₄⁺-base fertilizer induced not N₂O emissions. Microbial nitrification is the dominant contributor for N₂O production in North China Plain. The application of NH₄⁺-base fertilizer induced significant amount of N₂O emissions. Nitrification inhibitor can significantly reduce N₂O emissions.CO₂ emissions of control treatment is more than others, CO₂ emissions of NO₃^- treatment less than NO₃^-+Glucose treatment.（3）In the North China Plain, ammonium and nitrate with Glucose add soil simultaneously,N₂O emissions is higher then add only ammonium or nitrate. When content of glucose is 0.5 mg.kg-1, N₂O emissions of treatment of ammonium and nitrate with Glucose is maximum. NO₃^- with Glucose add soil simultaneously, the peak of N₂O emissions apeared the second day of cultivation, NH₄⁺ with Glucose add soil simultaneously, the peak of N₂O emissions appeared the first day of cultivation. When Carbon source is sufficient, Microbial denitrification is the dominant contributor for N₂O production in North China Plain, N₂O emissions obviously increased. When content of glucose is 2.0 mg/kg, CO₂ emissions is highest.CO₂ emissions is increased during later period, because mineralization.（4）Ammonium with different available Carbon in the North China Plain, indicate N₂O emissions of treatment of ammonium with Glucose is maximum, NH₄⁺ with Glucose treatment,N₂O emissions is the most,4039.85μgN/kg/d,NH₄⁺ with Pectin,N₂O emissions is 2533.43μgN/kg/d, the peak appeared the first day of cultivation. NH₄⁺ with Cellulose and NH₄⁺ with Straw treatment, N₂O emissions is less than only NH₄⁺ treatment. CO₂ emissions of NH₄⁺ with Cellulose treatment continued is higher.Ammonium with different available Carbon treatment,CO₂ accumulated emissions is more than control treatment and only NH₄⁺ treatment.（5）Nitrate with different available Carbon in the North China Plain, indicate N₂O emissions of treatment of nitrate with Pectin is maximum.NO₃^- with Glucose treatment and NO₃^- with Pectin treamenr,N₂O emissions is the most, 990.67、1383.42μgN/kg-/d, the peak appeared the first day of cultivation. N₂O emissions of NO₃^- with Cellulose treatment is less than control treatment during early period and more than control treatment during later period. Nitrate with different available Carbon treatment,CO₂ accumulated emissions is more than control treatment and only Nitrate treatment.CO₂ emissions of NO₃^- with Starch treatment is continuely increased. CO₂ emissions of NO₃^- with Cellulose and NO₃^- with Straw treatment increased during early period and induced during later period.