减量施氮对雨养区春玉米产量和环境效应的影响

通过3年田间试验，研究了减量施氮（N）对雨养区春玉米产量、温室气体排放、土壤硝态氮（NO-3-N）残留的影响。试验于2013年4月至2015年9月在中国科学院长武黄土高原农业生态试验站进行，供试作物为春玉米，半覆膜种植，设常规施氮（N200）和减量施氮（N150）2个处理，定期测定土壤矿质N和氧化亚氮（N2O）气体含量。结果表明：虽然N150处理较N200处理施N量减少了25%，但玉米产量无显著变化（P>0.05），三年平均为13.4（N200）、13.3（N150）t·hm-2；N150处理N2O累积排放量较N200处理降低24.3%；N200处理0~200 cm土壤剖面NO-3-N残留量平均为210.2 kg·hm-2，N150处理则低至115.1 kg·hm-2；N200和N150处理的生育期耗水量差异不显著（P>0.05）。在渭北雨养农业区，春玉米在常规施N的基础上减量25%，不仅能维持作物产量，还能有效降低N2O排放和NO-3-N的残留。

Effect of reduced nitrogen fertilization on spring maize production and environmental impacts in rain-fed ar-eas

An experiment was designed to examine effects of reduced nitrogen(N)fertilization on spring maize production, greenhouse gas emissions and soil nitrate nitrogen(NO-3-N)residue in under rain-fed farming systems. The three-year field experiment was performed at the Changwu State Key Agro-Ecological Experimental Station of the Loess Plateau, Chinese Academy of Sciences. Two treatments:tradi-tional nitrogen(N200)and reduced nitrogen(N150)were employed. Soil mineral nitrogen and N2O emissions were determined regularly. Results showed that there were no significant differences in maize grain yields between N200(13.4 t·hm-2)and N150(13.3 t·hm-2). Howev-er, the cumulative N2O emissions in N150 was decreased by 24.3%, compared with that of N200. Within 0~200 cm soil profile, NO-3-N residue in the N200 treatment was averagely 210.2 kg·hm-2, while it was reduced to 115.1 kg·hm-2 in N150 treatment. During the growth period of spring maize, the water consumption ranged from 354 to 493 mm, with no significant difference between the two treatments(P>0.05). Reducing 25%of N fertilizer against the traditional N fertilization not only guarantees the maize yields, but also effectively decreases the N2O emissions and soil NO-3-N residues in the cropping system in the Weibei rain-fed agricultural area.