缺氮对作物生长发育不利，但氮素过多对作物生长、产量及品质也有不良影响。在氮素过多的情况下，光合作用产生的碳水化合物大量用于合成蛋白质、叶绿素及其它含氮化合物，减少了糖的积累，妨碍了纤维素和果胶的形成，使茎叶疯长，组织柔软，容易倒伏，谷类作物会贪青迟熟，籽粒不饱满，产量下降;由于叶过茂，通风透光差，加上组织柔软，容易发生病虫害;对于果树，氮过多会影响花芽分化，花期氮过多会引起落蕾落花，后期氮肥过多果实成熟期会推迟，着色差，果实味淡。

Nitrogen deficiency is harmful to crop growth and development, but excessive nitrogen has adverse effects on crop growth, yield and quality. In the case of excessive nitrogen, a large amount of carbohydrate produced by photosynthesis is used to synthesize protein, chlorophyll and other nitrogen-containing compounds, which reduces the accumulation of sugar, hinders the formation of cellulose and pectin, makes the stem and leaf grow rapidly, the tissue is soft and prone to lodging, the grain crops will be greedy for green and late ripening, the grain is not full, and the yield is decreased; due to overgrown leaves, poor ventilation and light transmission, plus For fruit trees, too much nitrogen will affect flower bud differentiation, too much nitrogen at flowering stage will cause bud and flower drop, too much nitrogen at later stage will delay fruit ripening, color difference and fruit taste.