Human activities have significantly altered the global nitrogen cycle, increasing nitrogen input by about double, leading to serious environmental consequences. Nitrogen is crucial for ecosystem function, and human activities such as agriculture, fossil fuel combustion, and nitrogen-fixing crops have increased nitrogen availability and mobility. This has resulted in higher concentrations of greenhouse gases like N₂O, increased photochemical smog, soil nutrient loss, acidification, and nitrogen transfer to coastal areas. Additionally, human activities have increased organic carbon storage, reduced biodiversity, and altered estuarine and coastal ecosystems. Nitrogen deposition has led to changes in ecosystem composition and biodiversity, favoring nitrogen-demanding species and reducing plant diversity. In aquatic systems, increased nitrogen has caused eutrophication, leading to oxygen depletion, loss of biodiversity, and toxic algal blooms. Nitrogen also contributes to acidification, which affects aquatic ecosystems by mobilizing toxic aluminum and reducing acid-neutralizing capacity. The global nitrogen cycle is influenced by various sources, including nitrogen fertilizers, fossil fuel combustion, nitrogen-fixing crops, and mobilization of nitrogen from ecosystems. Human activities have increased nitrogen fixation and mobilization, leading to significant changes in the nitrogen cycle. However, uncertainties remain regarding the extent of these changes and their long-term impacts. Future management strategies must focus on reducing nitrogen fixation and improving fertilizer efficiency to mitigate environmental impacts. Technologies that enhance nitrogen use efficiency and reduce nitrogen loss are crucial for sustainable agriculture. Additionally, restoring natural nitrogen traps and managing nitrogen emissions from fossil fuel combustion are essential to address the challenges posed by human-induced changes in the nitrogen cycle.Human activities have significantly altered the global nitrogen cycle, increasing nitrogen input by about double, leading to serious environmental consequences. Nitrogen is crucial for ecosystem function, and human activities such as agriculture, fossil fuel combustion, and nitrogen-fixing crops have increased nitrogen availability and mobility. This has resulted in higher concentrations of greenhouse gases like N₂O, increased photochemical smog, soil nutrient loss, acidification, and nitrogen transfer to coastal areas. Additionally, human activities have increased organic carbon storage, reduced biodiversity, and altered estuarine and coastal ecosystems. Nitrogen deposition has led to changes in ecosystem composition and biodiversity, favoring nitrogen-demanding species and reducing plant diversity. In aquatic systems, increased nitrogen has caused eutrophication, leading to oxygen depletion, loss of biodiversity, and toxic algal blooms. Nitrogen also contributes to acidification, which affects aquatic ecosystems by mobilizing toxic aluminum and reducing acid-neutralizing capacity. The global nitrogen cycle is influenced by various sources, including nitrogen fertilizers, fossil fuel combustion, nitrogen-fixing crops, and mobilization of nitrogen from ecosystems. Human activities have increased nitrogen fixation and mobilization, leading to significant changes in the nitrogen cycle. However, uncertainties remain regarding the extent of these changes and their long-term impacts. Future management strategies must focus on reducing nitrogen fixation and improving fertilizer efficiency to mitigate environmental impacts. Technologies that enhance nitrogen use efficiency and reduce nitrogen loss are crucial for sustainable agriculture. Additionally, restoring natural nitrogen traps and managing nitrogen emissions from fossil fuel combustion are essential to address the challenges posed by human-induced changes in the nitrogen cycle.