Urea has the highest nitrogen content equal to 46.6%. This percentage of nitrogen is much higher then any other fertilizer. It does not change the pH of the soil and can be used to all types of Solis and crops, since after its assimilation by plants through the interaction of nitrifying bacteria, it leaves behind only CO j in the soil.
Urea is the most popular concentrated solid straight nitrogen fertilizer. Its prills or granules are white in colour and free flowing. About 4 million twines is now produced annually in Pakistan. Urea is readily soluble in water. It contains 46% Nitrogen in amide (NI-12) form which is changed to ammonium (NH3+) in the soil. Urea sometimes contains small quantities of biuret, a toxic impurity but commercial supplies are ensured at a level not toxic. Poor agronomic practices may cause loss to the atmosphere; therefore it requires high degree of understanding for efficient use. Because of its high water solubility, it is well suited for use in solution fertilizers or foliar sprays.