外加可溶性碳源对华北典型农田土壤N_2O、CO_2排放的影响

Influence of Soluble Carbon on N_2O and CO_2 Emissions from Soil of Typical Farm-land in North China

以华北平原典型农田土壤为对象,运用静态培养系统研究方法,设置室内培养试验,研究添加不同浓度葡萄糖对土壤N2O、CO2排放的影响。结果表明:碳氮配施的外源添加方式明显促进N2O和CO2排放,其排放通量均高于对照组和只添加氮源的处理。在配施碳源葡萄糖浓度为0.5g/kg时N2O排放通量最高(NH4+组2 500μg/(kg·d),单位以N计,下同,NO-3组1 500μg/(kg·d)),4.0g/kg时N2O排放通量最低(NH4+组500μg/(kg·d),NO-3组800μg/(kg·d));葡萄糖浓度为2.0g/kg时CO2排放通量最高(NH4+组500mg/(kg·d)),0.5g/kg时CO2排放通量最低(NH4+组100mg/(kg·d))。从培养开始到结束,只添加氮源的土壤NH4+含量变化不明显,NO-3含量增至29.21mg/kg(NH4+组)和62.25mg/kg(NO-3组);而配施葡萄糖的土壤NH4+含量降为不足1mg/kg(NH4+组),NO-3含量明显减少。N2O累积排放通量与葡萄糖浓度呈负相关(NH4+组),CO2累积排放通量与葡萄糖浓度呈正相关。分析结果表明,外加可溶性碳源明显减少土壤中NH4+和NO-3含量,并且促进土壤N2O、CO2排放,其排放通量大小与C/N比有关。

The influence of different concentrations of glucose(Glu)on the emission of N2O and CO2 from soil of typical farm-land in north China was studied.The static culture systems were adopted in an indoor cultivation experiment.Compared with single nitrogen fertilizer,combined application Glu and NH4+ or NO3 fertilizer significantly promoted the emission of N2O and CO2from soil.The emission flux of N2O by treatment of the application of Glu 0.5g/kg(NH4+ group reached 2 500μg/(kg·d),NO3 group reached 1 500μg/(kg·d)) was the highest and the emission flux by treatment of the application of Glu 4.0g/kg(NH4+ group only 500 μg/(kg·d),NO3 group only 800μg/(kg·d))was the lowest.And the emission flux of CO2 by treatment of the application of Glu 2.0g/kg(NH4+ group reached 500mg/(kg·d))was the highest and the emission flux by treatment of the application of Glu 0.5g/kg(NH4+ group only 100mg/(kg·d))was the lowest.From cultivation start to finish,soil NH4+ content of single nitrogen fertilizer did not change significantly,combined application Glu and NH4+ fertilizer reduced to less than 1mg/kg,and soil NO3 content of single nitrogen fertilizer increased to 29.21mg/kg(NH4+ group)and 62.25mg/kg(NO3 group),combined application Glu and NH4+ or NO3 fertilizer significantly reduced.It showed a negative correlation between the cumulative emission flux of N2O and the concentrations of Glu(NH4+ group)and a positive correlation between cumulative emission flux of CO2 and the concentrations of Glu.Compared with single nitrogen fertilizer,combined application Glu and NH+ 4 or NO3 fertilizer significantly reduced soil NH4+ and NO3 content and promoted the emission of N2O and CO2 from soil,the emission flux was associated with C/N proportion.