氮肥施用对西南地区紫色土冬小麦N_2O释放和反硝化作用的影响

N2O是重要的温室气体之一,由此引起的全球变暖和臭氧层破坏是当今重要的环境问题。采用遮光密闭箱和气相色谱法研究了氮肥施用对小麦地N2O释放和反硝化作用的影响。结果表明,小麦生长季节里,高氮、中氮以及不施氮处理N2O平均排放通量分别为2.71、2.42、1.97 gN.hm-.2d-1;尿素、硫酸铵、硝酸钾3种氮肥品种处理下,平均N2O排放通量分别为2.42、2.14、3.13 gN.hm-2.d-1。小麦生长季节里,高氮、中氮以及不施氮处理平均反硝化速率分别为4.91、4.50、1.67 gN.hm-.2d-1;尿素、硫酸铵、硝酸钾3种氮肥品种处理下,平均反硝化速率分别为4.50、3.68、5.29 gN.hm-.2d-1。氮肥施用明显促进了土壤-植物系统中N2O排放通量和反硝化作用,氮肥施用量水平和N2O排放通量、反硝化作用呈正相关。硝酸钾对N2O排放通量和反硝化作用贡献最大,硫酸铵最小。研究还表明,小麦地N2O释放和反硝化作用与季节有一定相关性,温度较高季节排放量及反硝化作用明显,反之则较弱。

Effect of Nitrogen Fertilizer for Wheat on N_2O Emission and Denitrification in Purple Soil

In this study,the static chamber and gas chromatography（GC）methods were used to investigate the effect of fertilizer application on N2O emission and denitrification during the wheat growing season.The results showed that nitrogen fertilizer application enhanced N2O e-mission and denitrification in the agro-ecosystem.The average N2O emission rates were 2.71,2.42 gN.hm-2.d-1 and 1.97 gN.hm-2.d-1 for high nitrogen（HN）,medium nitrogen（MN）,and no nitrogen（NN）treatments,respectively,and the average N2O emission rates were 2.42,2.14 gN.hm-2.d-1 and 3.13 gN.hm-2.d-1 for urea（UN）,ammonium sulphate（AS）,and potassium nitrate（PN）treatments,respectively.The average denitrification rates were 4.91,4.50 gN.hm-2.d-1 and 1.67 gN.hm-2.d-1 for HN,MN,and NN treatments,respectively,and the aver-age amounts of denitrification were 4.50,3.68 gN.hm-.2d-1 and 5.29 gN.hm-.2d-1 for UN,AS,PN treatments,respectively.Significantly posi-tive correlations between the amounts of fertilizer application and N2O emission,denitrification were observed.PN contributed most of N2O emission and denitrification,on the contrary,AS contributed the least among the three fertilizers.Seasonal variation was found for the N2O e-mission and denitrification,while higher N2O emission and denitrification was obtained in warm season than that in cold season.