Which form of nitrogen is most readily taken up by plants?

Nitrate is the form of nitrogen that plants most readily absorb from the soil. This is largely due to its solubility and mobility in the soil, allowing it to be easily transported through soil water to plant roots. Once plants take up nitrate, they convert it into amino acids and proteins, which are essential for their growth and development.

Nitrate is favored because it can be taken up directly by plant roots without requiring further transformation. In contrast, other forms of nitrogen such as ammonium, while usable by plants, can accumulate in the soil and alter pH levels, potentially leading to toxicity in high concentrations. Urea, on the other hand, must first be converted to ammonium via microbial activity in the soil before it becomes available to plants, introducing a delay in availability. Organic nitrogen requires decomposition to release inorganic forms that plants can utilize, making it less readily available compared to nitrate. Therefore, nitrate is the most efficient and effective form of nitrogen for plant uptake.