Nitrogen fixation by bacteria: Certain bacteria like Rhizobium and Azotobacter convert atmospheric nitrogen into ammonia, which can then be used by plants.
Lightning: Electrical storms can break down nitrogen molecules in the atmosphere, leading to the formation of nitrogen oxides that can eventually be washed down to the earth by rain.
Industrial processes: Human activities such as combustion and industrial processes can release nitrogen oxides into the atmosphere, contributing to nitrogen deposition on land and water bodies.
