崇明岛芦笋大棚土壤中硝酸盐的动态变化

在芦笋不同生长阶段,对崇明岛芦笋大棚土壤的硝酸盐含量进行测定.结果表明,研究期内棚龄为10年、4年和1年的大棚0～40 cm土壤硝酸盐含量分别为248.3～651.0 mg N·kg-1、18.4～928.4 mg N·kg-1和52.4～556.2 mg N·kg-1,存在硝酸盐的累积现象.受氮肥施用和芦笋生长对氮素吸收的综合影响,土壤硝酸盐含量在不同芦笋生长阶段变化显著.夏笋生长末期土壤硝酸盐累积现象最为严重,并存在向下迁移趋势.3个大棚土壤均出现了酸化和次生盐渍化现象,硝酸盐累积是造成高棚龄大棚土壤次生盐渍化的重要原因.

Dynamic variations of nitrate contents in the asparagus greenhouse soils from Chongming Island

The dynamic variations of nitrate contents in the asparagus greenhouse soil at different growth stages of asparagus in Chongming Island were measured. The result showed that contents of nitrate in the soils of 10-year, 4-year, and 1-year old asparagus greenhouses ranged from 248.3 to 651.0 mg N·kg^-1, from 18.4 to 928.4 mg N·kg^-1 and from 52.4 to 556.2 mg N·kg^-1, respectively. Generally, nitrate accumulated in the soils of all the three greenhouses. Both nitrogen fertilizer applications and plant uptakes of nitrogen caused significant variations of soil nitrate contents at different growth stages. The nitrate was most seriously accumulated in soil at late growth stage of asparagus in summer, which also resulted in heavy leach of nitrogen to the deeper layer. Soil acidifications and salinizations were found in all the three greenhouses. Nitrate accumulation was one of the important factors that caused soil salinization in the 10-year old asparagus greenhouse.