植物除用根系吸收矿质养分外,茎叶也能吸收,叫根外营养。利用根外营养方法施肥叫根外追肥。根外追肥用肥量少,见效快,但不能代替根的吸收。只能作为及时补救根部吸收营养不足的辅助性措施。常用于以下几种情况:植物旺盛生长期急需肥料;根系受伤或植物生长后期根系木栓化;树木、花卉移栽后根系暂时吸收困难。常用的无机肥料有:磷酸二氢钾、尿素、过磷酸钙及微量元素等。 In addition to plant roots to absorb mineral nutrients, the stems and leaves can absorb, called root nutrition. Use of root nutrition means fertilizer called root top dressing. Top dressing fertilizer with less, quick, but can not replace the root absorption. It can only serve as a supplementary measure to remedy the problem of insufficient nutrition in the roots. Commonly used in the following situations: strong plant growth period urgently needed fertilizer; root injury or late plant growth root cork; roots, flowers, transplanted roots temporarily absorbed difficulties. Common inorganic fertilizers are: potassium dihydrogen phosphate, urea, superphosphate and trace elements.