Plants primarily obtain nitrogen from the soil through a process called nitrogen fixation. Certain bacteria in the soil convert atmospheric nitrogen (N₂) into forms that plants can absorb, such as ammonium (NH₄⁺) or nitrate (NO₃⁻). Some plants, like legumes, have symbiotic relationships with these bacteria in their root nodules, enhancing their nitrogen uptake. Nitrogen is vital for plants as it is a key component of amino acids, proteins, and nucleic acids, playing a significant role in plant growth and development.