摘要
通过对黄土高原大棚蔬菜不同施肥水平及采收期试验，研究了氮肥施用量对蔬菜产量、品质以及土壤硝酸盐积累的影响。结果表明：在土壤氮素水平较低情况下，随氮肥施用量的增加蔬菜产量随之提高，当黄瓜施用量达300kg·hm^-2、芹菜施用量达400kg·hm^-2时，其产量分别较对照提高16．7％和37．5％，而菜体中硝态氮含量与对照差异不大；但当施用量超过500kg·hm^-2及600kg·hm^-2时，会使黄瓜、芹菜产量逐渐下降，同时导致蔬菜及土壤中硝态氮含量迅速增高，使蔬菜达到高污染水平。施肥后随时间的推移，蔬菜中的硝酸盐含量逐渐降低，在中等施肥条件下30d后可达到食用水平。黄土高原土壤氮素淋溶强烈，在氮肥施用后15d，50cm左右土层中硝态氮累积量最多形成峰值，且随时间的推移其峰值有逐渐向下移动的趋势。本实验证实：适量氮肥有利于蔬菜生长，还可有效减少氮素污染，在黄土高原大棚蔬菜生产中氮肥最佳用量为400—500kg·hm^-2，同时应严格控制采收时间，在蔬菜采食前30d内不能施用氮肥。
The effect of different nitrogen fertilization rates and harvest times on nitrate accumulation in the tissues and yield of celery and cucumber as well as on soil were studied under greenhouse in the Loess Plateau. Results show that concentration of nitrate in plants and soil increases with increasing nitrogen supply under lower soil nitrogen levels. Specifically, celery and cucumber yield increases by 16.7% and 37.5% over the control when nitrogen is applied at 300 kg·hm^-2 and 400 kg·hm^-2 respectively. There is significant difference in nitrate content between the treatment and the control. The nitrogen application of 500 kg·hm^-2 for cucumber and 600 kg·hm^-2 for celery fields leads to significant decline in yield and remarkable increase in nitrate concentration in plants and soils, and a serious pollution of the vegetables. With plants development, nitrate content in vegetable plants gradually drops to edible level 30 days after moderate nitrogen application. Soil nitrogen leaches intensively in the Loess Plateau which leads to nitrate accumulation in the 50 cm soil layer, at most 15 days after nitrogen fertilization, though maximum accumulation gradually drops with plant growth and development. Subsequently, an adequate supply of nitrogen markedly raises vegetable yield and efficiently reduces nitrate pollution. Optimum application of nitrogen fertilizer should be restricted to 400 - 500 kg·hm^-2, and vegetable plant should not be fertilized by nitrogen 30 days before harvest in greenhouse in the Loess Plateau.
出处
《中国生态农业学报》
CAS
CSCD
2008年第3期555-559,共5页
Chinese Journal of Eco-Agriculture
基金
陕西省科技厅项目(2006K03-G11-01)资助
关键词
黄土高原
大棚蔬菜
氮肥
硝酸盐积累
采收时间
Loess Plateau, Greenhouse vegetable, Nitrogen fertilizer, Nitrate accumulation, Harvest time
