不同施氮水平对稻麦轮作农田氧化亚氮排放的影响

利用江苏常熟田间随机区组试验，以密闭箱法采集气样，气相色谱分析N2O浓度，对稻麦轮作制下不同施氮水平的土壤N2O排放进行了观测，探讨了不同施氮水平对稻麦轮作农田氧化亚氮排放的影响。结果表明，土壤N2O排放量受施氮量的影响，稻季和麦季N2O排放量都随旌氮量的增加而增加；稻季N2O排放量最大峰值出现在烤田复水期间，其排放量大小主要受基肥和分蘖肥施用量的影响，并随施氮量的增加而增大；麦季最大峰值出现在气温回暖的第二次追肥后，排放量的最大峰值也随施氮量的增加而增大；稻麦轮作土壤N2O排放以麦季的排放为主，麦季N2O累积排放量在轮作周期中占三分之二。

Effect of Nitrogen Fertilizer Rates on Nitrous Oxide Emission from Paddy Field Under Rice-Wheat Rotation

Research efforts have increasingly focused on finding the environmental and artifical influence factors of nitrous oxide （N2O） emission from paddy fields, especially from the rice-wheat rotation system. This paper studied the season characters and the effect of nitrogen fertilizer rates on N2O emission during the whole period of rice-wheat rotation from soil in Changshu, Jiangsu Province of China. The treatments of fertilizer N（ urea ） in field study were 0, 100, 150, 200, 250, 300 and 350 kg N·hm^-2 for rice growing season and were 0, 100, 150, 200, 250 and 300 kg N·hm^-2 for wheat growing season respectively. Experimental plots in field study followed randomized block design, and each treatment was triplicate. The emitted gases from the systems were collected with closed chambers method, and the N2O was detected by gas chromatograph. The N2O emission increased with the increase mounts of fertilizer N in the whole rotation season. In rice growing season, the N2O emission peaks occurred during the mid-season aeration rather than other periods, and increased with the increase total mounts of base fertilization and fertilizer N during tillering period. Only enough fertilizer N would meet the both need of the plants and the nitrobactefla. Comparing with rice growing season, the soil in wheat growing season were not flooding but keeping moist. Therefore the N2O emission in wheat growing season accounted for about 2/3 of that in the whole rotation season, and the N2O emission peaks occurred when the second topdressing was applied.