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以露地甘蓝土壤为试材,采用原位测定农田氨挥发的方法,研究北京地区不同施氮情景下、不同施肥阶段露地甘蓝生长过程中土壤氨挥发情况及其时间变化规律。结果表明:1)甘蓝地土壤氨挥发主要发生在施肥后1~3周内,基肥阶段的氨挥发主要发生在施肥后18d,追肥阶段的氨挥发发生在施肥后7d;2)甘蓝地施用基肥至定植灌水前,各地块氨排放通量逐渐降低,尤其是第4天氨排放通量都达到最低;定植灌水后,各地块氨排放通量显著升高,且在施基肥后第5~6天(灌水后第1天)出现第一个排放峰值;3)第一次追肥(施肥与灌水同步)氨排放通量峰值出现在第1天;第二次追肥受灌溉及温度的共同影响,氨排放通量峰值出现在第3天;4)甘蓝整个生长周期内不同施氮情景下各地块土壤氨排放总量为7.789~39.324kg·hm~(-2),并且随施氮量的增加而增加,各情景的氨累计挥发率为5.62%~6.78%;5)适当施用氮肥可以提高甘蓝的产量,但是过度施用氮肥不仅不会增加甘蓝产量,还会增加氨挥发量。
A field test was conducted to determine the ammonia volatilization in farmland in order to study the ammonia volatilization and its time variation during the growth of cabbage in different fertilization stages under different N application scenarios in Beijing. The results showed as follows: 1) Ammonia volatilization mainly occurred within 1 ~ 3 weeks after fertilization in the cabbage soils. Ammonia volatilization in the basal fertilizer stage occurred mainly 18 days after fertilization and ammonia volatilization occurred in the top dressing stage 7 days after fertilization. 2) Before the irrigation, the fluxes of ammonia emission decreased gradually in all plots, especially the ammonia fluxes reached the lowest on the 4th day. After the irrigation, the fluxes of ammonia in all plots increased significantly, ~ 6 days (the first day after irrigation), the first emission peak appears; 3) The first top-dressing (fertilization and irrigation synchronization) peak of ammonia discharge occurs on the first day; the second top-dressing is affected by both irrigation and temperature The peak of ammonia emission flux appeared on the 3rd day; 4) The total ammonia emission of soil in all plots was 7.789 ~ 39.324kg · hm -2 under different nitrogen application conditions in the whole growth cycle of cabbage, The cumulative volatilization rate of ammonia in all scenarios was 5.62% ~ 6.78%. 5) Appropriate application of nitrogen fertilizers could increase the yield of cabbage, but excessive application of nitrogen fertilizer would not only increase the yield of cabbage, but also increase the amount of ammonia volatilization.