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氮是蛋白质的必要成分,所有形式的生命都需要大量的氮。对于动植物来说,氮是限制生长最普遍的因素。虽然氮是自然界广泛存在的元素,几乎构成大气的80％。然而它又是一种稀少的营养资源,这是由于大气中氮的形态非常不活泼,隋性很大,它对绝大多数生物都无直接利用价值。只有当氮被固定或与某种其它元素如氢和氧结合在一起时,才能进入生物界。现今氮的固定有三种途径:1、自然界闪电放电、宇宙辐射、汽车发动、火山爆发等使氮与氧自然结合;2、工业制造氮肥;3、生物固氮。自然界合成氮在一定条件下,是十分有限的,解决不了现代氮素的需求量。化肥的生产使人类大规模地利用空气中的氮资源,为世界农业生产率的提高作出了巨大的贡献。但是,化肥的大量使用加深了矿物能源消耗和环境污染。实践
Nitrogen is an essential ingredient in proteins, and large amounts of nitrogen are required for all forms of life. Nitrogen is the most common limiting factor for plants and animals. Although nitrogen is a naturally occurring element, it constitutes almost 80% of the atmosphere. However, it is a scarce nutritional resource because of the very inert and inert form of nitrogen in the atmosphere, which is of no immediate value to most organisms. It is only when nitrogen is immobilized or combined with some other element, such as hydrogen and oxygen, that it enters the organism. Now there are three ways to fix nitrogen: 1, natural lightning discharge, cosmic radiation, car launch, volcanic eruption and so naturally combined with nitrogen and oxygen; 2, industrial nitrogen fertilizer; 3, biological nitrogen fixation. Natural synthetic nitrogen under certain conditions, is very limited, can not solve the demand of modern nitrogen. The production of fertilizers makes mankind make large-scale use of nitrogen resources in the air and made great contributions to the improvement of world agricultural productivity. However, the heavy use of fertilizers has deepened the mineral energy consumption and environmental pollution. practice