【摘要】 通过设计不同纯氮(N)施入水平(分别为0、150、300、600、900和1200 kg/hm2共6个处理),重点研究了北方褐土区夏玉米大田土壤硝态氮(NO3--N)运移动态,并讨论了夏玉米N肥的经济环保施用量及其相关机制。试验结果表明,土壤-作物系统内土壤NO3--N垂直方向上的运移有向上、向下两个方向。不同生育时期土壤NO3--N运移特征不同,拔节期以前,0~40 cm土层随N肥用量的增加,土壤NO3--N含量快速增加,40 cm以下深度土壤NO3--N含量变化不明显,随植株的生长和根系的壮大,0~100 cm土层内的NO3--N整体运移活跃。土壤有自动调节NO3--N含量的功能,各土层NO3--N含量均存在一个最低点,其中耕层为3.1 mg/kg附近;玉米旺盛生长期各土层内土壤NO3--N饱和值在20.33 mg/kg附近,施肥量过多,NO3--N向下运移,造成资源浪费和对土壤环境质量的威胁。北方褐土区夏玉米最高纯N施用量应控制在600 kg/hm2以内,300 kg/hm2(纯N)是最为环保、经济的施肥量。更多还原

【Abstract】 In order to study economical and environmental nitrogen(N) fertilization in summer maize in North China Plain,field experiment was conducted at Wang Wenhua’s field in Luojiazhuang village,Zhengding county.According designing 6 N rates(0,150,300,600,900,1200 kg/hm2),this paper studied the moving dynamic status of soil nitrate nitrogen(NO3——N) in summer maize field,and discusses the economical and environmental N rates and its theories.The main results as follows: for soil NO3——N there were two orientation of up and down in uprightness moving in soil-crop system.There were different moving characters for soil NO3——N in different growth stages: up to 40 cm depth before stem elongation stage soil NO3——N content increased speed with N rates increasing,while there was no clearly changes under 40 cm depth.With the growth of plant and the development of root,the movement of 0～100 cm depth soil NO3——N became activated.It indicated the absorbing and applying of plant to N fertilization mainly concentrated in root depth soil layer.The result showed the lowest point of balance for soil NO3——N content in one layer was about 3.1 mg/kg and in the bloom of maize growth the saturated point in one soil was about 20.33 mg/kg.The highest N rate for environmental was under 600 kg/hm2,and the economical rate was 300 kg/hm2.更多还原