引黄灌区设施菜田硝态氮淋失的季节性特征

以宁夏引黄灌区设施菜田番茄-黄瓜轮作体系为研究对象,采用田间定位试验与实地观测相结合的研究方法,对设施菜田硝态氮淋洗的季节特征及其环境因子和施肥管理对硝态氮淋洗的影响进行研究。研究结果表明:硝态氮淋失呈现明显的季节变化,峰值出现在7月夏季休闲期,黄瓜季(秋冬茬)淋洗显著高于番茄季(冬春季),常规施肥周年硝态氮淋洗量平均为185.7 kg·hm-2,优化施肥和调节碳氮比两处理硝态氮淋洗量比常规处理分别降低了10.6%和8.3%。设施菜田硝态氮淋失与浅层地下水位、土壤温度、土壤水分等环境因子季节性变化关系密切,浅层地下水位与硝态氮的淋失量呈极显著负相关,浅层地下水位埋深越浅,硝态氮淋失量越大;土壤水分和温度与硝态氮的淋失量呈显著正相关,随着土壤表层温度和含水量升高,硝态氮淋失增多。

Seasonal Changes of Nitrate Leaching in Greenhouse Vegetable Field in Yellow River Irrigation Region of Ningxia, China

Extensive use of nitrogen fertilizers has caused nitrate leaching in greenhouse vegetable fields. A field experiment was carried out to investigate the seasonal changes of nitrate leaching and the effects of environmental factors and fertilization practices in a greenhouse tomato and cucumber rotation system in the Yellow River Irrigation Region of Ningxia. Nitrate leaching showed obvious seasonal changes. The leaching peak occurred during summer fallow period in July. Nitrate leaching losses were significantly higher in cucumber(autumn-winter season) than in tomato season(winter-spring season). The nitrate leaching for the whole year was about 185.7 kg·hm^-2 in the conventional fertilization, while the amount of nitrate leaching decreased by 10.6% and 8.3% in optimal fertilization and optimal fertilization plus regulating soil C/N ratios, respectively. Losses of nitrate leaching were significantly negatively correlated with shallow groundwater depth, but significantly positively with soil moisture and soil temperature. These findings would be useful for reducing nitrate leaching from greenhouse vegetable systems.