南京郊区番茄地中氮肥的效应与去向

Use efficiency and fate of fertilizer N in tomato field of Nanjing suburb.

采用田间小区和微区试验,研究了施用化学氮肥对南京郊区菜地番茄产量、氮肥去向及氮素损失的影响.结果表明,由于土壤和有机肥供氮充分,氮肥施用未增加番茄产量.用差值法计算得到的氮肥利用率在14.5%～22.5%之间.15N标记尿素微区试验表明,施入氮量的16.6%～28.8%被作物吸收,氮素总损失为34.2%～46.0%.施用化学氮肥增加了土壤剖面中的硝酸盐含量,番茄收获时,10%～10.2%的标记尿素被淋洗到40cm以下土层.增施化学氮肥也显著增加了菜地土壤的反硝化损失和N2O排放,其中反硝化损失占施入氮量的5.50%～6.01%;N2O排放量占施入氮量的2.62%～4.92%.但番茄生长期间未检测到氨挥发.减少氮肥用量或施用包衣尿素可降低菜地施用氮肥的环境风险,特别是减少硝酸盐淋洗和硝化反硝化损失.

Field plot and micro-plot experiments were conducted to investigate the use efficiency （ UE ） , fate, and loss of chemical fertilizer N in tomato field of Nanjing suburb. The results showed that the application of chemical fertilizer N did not show any benefit to the tomato yield, due to the adequate N supply from native soil and organic manure amendment. The UE of fertilizer N calculated by difference method ranged from 14. 5% to 22. 5%. In mi- cro-plot experiment, 16. 6% - 28.8% of applied urea 15 N was recovered by the plant, and 34. 2% - 46. 0% of it was lost. Applying fertilizer N increased the nitrate content in 0 - 100 cm soil layer, and 10% - 10. 2% of urea 15N was leached to the depth below 40 cm at harvest time. N application increased the denitrification loss and N20 emission significantly, which occupied 5.50% -6. 01% and 2. 62% -4. 92% of the applied N, respectively. No ammonia volatilization was detected during the whole growth season. Reducing N application rate or applying coa- ted urea could decrease the environmental risks of N application in vegetable fields, especially the risks from nitrate leaching and nitrification-denitrification loss.