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(N_2O)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(P0.05),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(P0.05)。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N_2O排放和NO_3~--N的残留。

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

An experiment was designed to examine effects of reduced nitrogen(N) fertilization on spring maize production, greenhouse gas emissions and soil nitrate nitrogen(NO₃^--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:traditional 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). However, the cumulative N₂O emissions in N150 was decreased by 24.3%, compared with that of N200. Within 0~200 cm soil profile, NO₃^--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 NO₃^--N residues in the cropping system in the Weibei rain-fed agricultural area.