氮肥形态与大白菜产量及硝酸盐累积的关系

通过田间试验研究了不同形态氮肥对大白菜产量及硝酸盐累积的影响。结果表明 ,大白菜施用尿素比习惯施用碳酸铵更有利于获得高产 ,大颗粒尿素优于普通尿素 ,且净菜产量高。随氮肥追肥量增加 ,大白菜内叶硝酸盐含量增加 ,外叶则维持在一定水平上 ,大白菜外叶硝酸盐含量高于内叶。大量施用氮肥不仅产量低 ,净菜率低 ,而且使大白菜外叶硝酸盐累积水平高 ,并使土体中残留大量硝酸盐。

The Effect of Nitrogen Forms on Chinese Cabbage Yield and Nitrate Accumulation

Field experiment was conducted for studying the effect of nitrogen forms on the yield of Chinese cabbage and the accumulation of nitrate. The results showed that urea application could obtain higher yield than ammonia bicarbonate application, and compared with common urea, big granulated urea was more effective, obtaining higher yield and net yield. The amount of nitrate in inner leaves increased with the increasing rate of nitrogen fertilizer application, yet the content of nitrate kept at a certain amount in outer leaves. The content of nitrate in outer leaves was higher than that in inner leaves. Due to the application of high amount of nitrogen fertilizer in traditional cultivating practice, yield and net yield decreased, and quite an amount of nitrate accumulated in the outer leaves and soil profile.