微量元素指占生物体总质量0.01%以下，且为生物体所必需的一些元素。如铁、硅、锌、铜、碘、溴、硒、锰等。

微量元素为植物体必需但需求量很少的一些元素。这些元素在土壤中缺少或不能被植物利用时，植物生长不良，过多又容易引起中毒。在农业中，常以微量元素作种子处理、根外追肥来提高作物产量。

目前多数科学家比较一致的看法，认为生命必需的元素共有28种，在28种生命元素中，按体内含量的高低可分为宏量元素（或常量元素）和微量元素。微量元素占人体总质量的0.03%左右。这些微量元素在体内的含量虽小，但在生命活动过程中的作用是十分重要的。

Micronutrients are nutrients required by organisms throughout life in small quantities to orchestrate a range of physiological functions. For people, they include dietary trace minerals in amounts generally less than 100 milligrams/day - as opposed to macrominerals which are required in larger quantities. The microminerals or trace elements include at least iron, cobalt, chromium, copper, iodine, manganese, selenium, zinc and molybdenum. Micronutrients also include vitamins which are organic compounds required as nutrients in trace amounts.