东北黑土玉米单作体系氨挥发特征研究

采用通气法测定了东北黑土玉米单作体系田间土壤的原位氨挥发。试验设5个氮肥用量处理，即:施氮量（N）分别为0、150、225和300 kg/hm2（用N0、N1、N2 和N3表示），基施氮肥和拔节期追肥各1/2，其中N3为习惯施肥；同时设置优化施肥处理N4，用量为N 225 kg/hm2，基施氮肥、拔节期和孕穗期追肥各1/3。结果表明，来自肥料的氨挥发持续时间较短，一般发生在施肥后的7 d内。由于追肥期高温低湿，追肥期氨挥发量显著高于基施氮肥。随施氮量增加，氨挥发损失增加；优化施肥（N4）的氨挥发损失量明显低于习惯施肥，N1、N2、N3和N4处理来自氮肥的氨挥发依次为N 5.09、9.18、13.47和7.14 kg/hm2，相当于施氮量的3.39%、4.08%、4.49%和3.17%。可见，优化施肥对于我国东北集约化农区节省氮肥和提高氮肥利用率有重要意义。

In situ study of ammonia volatilization from black soil with maize monoculture system

Ammonia volatilization (AV) from soil is an important pathway for fertilizer N loss from field, while less information is available on AV from black soil in Northeast China. For understanding the seriousness of AV in this area, a venting method was used to investigate AV from black soil in maize monoculture system, treatments of nitrogen fertilizer (Urea) application included: (1) N₀ (Control, no nitrogen application); (2) N₁ (N 150 kg/hm²); (3) N₂ (N 225 kg/ hm²); (4) N₃ (N 300 kg/ hm²).The N₃ represented the traditional N application, and for N₁, N₂, and N₃, 1/2 was used before sowing as basal, and 1/2 used at jointing stage as top-dressing. One more treatment was added as N₄ (N 225 kg/ hm²), 1/3 the total amount was used respectively before sowing, at jointing stage，and at booting stage, and this represented optimized N application approach. In field condition，it was found that ammonia volatilization lasted short，and took place within a week after N application. The amount of AV from N fertilizer as top-dressing was found to be higher than that as basal, due to the higher temperature and the lower soil moisture at jointing stage and booting stage. The N loss through AV increased with the application rate of nitrogen fertilizer. For N₁, N₂ , N₃ and N₄ treatment, the amount of AV from N fertilizer were N 5.09, 9.18, 13.47 and 7.14 kg/ hm²，which were equivalent to 3.39%, 4.08%, 4.49% and 3.17% of fertilizer N applied, respectively. Optimized N application approach lowered the N loss by AV greatly compared to traditional N application. Therefore, optimized fertilization is of great importance for increasing N use efficiency and saving N fertilizer in intensive cropping area in Northeast China.