肥料常以酰胺、铵或硝酸盐的形态供给氮。各种形态氮各有优缺点。从理论上讲,与硝酸盐相比,铵态氮的优点是在植株体内运转和同化时耗能较少。无论液培或土培,铵态氮均更易为植株所吸收。铵离子较少因淋溶和反硝化而损失。但它的优点依赖于硝化速率。在土壤 pH 高时铵态氮易于挥发,也可能酸化。尿素是浓度最高的固体 N 肥,但在石灰质土壤和干旱条件下可能无效。它也 Fertilizers often supply nitrogen in the form of amide, ammonium or nitrate. Various forms of nitrogen have their own advantages and disadvantages. Theoretically, the advantage of ammonium nitrogen over nitrate is its less energy consumption during plant uptake and assimilation. Both liquid culture and soil culture, ammonium nitrogen are more easily absorbed by plants. Less ammonium ions are lost due to leaching and denitrification. But its advantages depend on the nitrification rate. Ammonium nitrogen tends to volatilize at high soil pH and may also be acidified. Urea is the highest concentration of solid N fertilizer, but may be ineffective in calcareous soils and dry conditions. It also