露地蔬菜的氮肥效应与氮素去向

采用田间小区和微区试验相结合,研究了小青菜、大白菜和番茄3种露地蔬菜的氮肥利用率及其氮素去向的差异。结果表明,在小青菜和大白菜上施氮增产显著(p<0.05),而在番茄上未表现出增产效应;施氮使3种蔬菜的吸氮量显著增加。用差值法和15N-示踪法测得的3种蔬菜氮肥利用率相当,且利用率随氮肥用量增加而降低。小青菜生长期间土壤氮素总损失低于10%,而大白菜和番茄生长期间土壤氮素损失分别为41.9%~48.6%和34.2%~46.0%。试验中未发现小青菜生长期间有氮素淋溶,大白菜和番茄分别有9.2%~10.9%和10%~10.2%的标记尿素被淋溶到40cm以下土层。

NITROGEN USE EFFICIENCY AND FATE OF N FERTILIZERS APPLIED TO OPEN FIELD VEGETABLES

The N use efficiency(NUE) and fate of N fertilizers applied to open field vegetables including green cabbage,Chinese cabbage and tomato were investigated by using field plot and microplot experiments.The results showed that application of N fertilizer significantly increased yield of green cabbage and Chinese cabbage(p<0.05),while the tomato's yield didn't increase.NUE was measured and compared by difference methods,including 15N-tracer method,and it was found that the NUE decreased with N application increasing.Total N loss in the soil of growing green cabbage was not more than 10% of applied N,while total N loss in the soil of Chinese cabbage and tomato were 41.9%～48.6% and 34.2%～46.0%,respectively.No N leaching was observed during the growing season of green cabbage,while 9.2%～10.9% and 10%～10.2% of labeled urea was leached under 40 cm soil layer during Chinese cabbage and tomato growing season,respectively.