The term for the process of converting nitrogen gas into a usable form is called nitrogen fixation. This process is essential for making atmospheric nitrogen available to plants, as most organisms cannot utilize nitrogen in its gaseous form. Nitrogen fixation can occur biologically through symbiotic relationships with certain bacteria, such as those in the root nodules of legumes, or through abiotic processes such as lightning. This conversion is crucial for maintaining nitrogen levels in the soil, ensuring healthy plant growth and supporting the entire food web.