This study examines 50-year trends in nitrogen use efficiency (NUE) of world cropping systems, focusing on the relationship between crop yield and nitrogen input to cropland. Using data from the Food and Agriculture Organization (FAO), the research analyzes the trajectories of 124 countries from 1961 to 2009, considering crop yield (expressed in kgN ha⁻¹ yr⁻¹) and total nitrogen inputs (synthetic fertilizers, manure, symbiotic fixation, and atmospheric deposition). The study reveals that while some countries have improved their agro-environmental performance, others have seen increased environmental losses due to excessive fertilization. Countries that rely more on symbiotic nitrogen fixation rather than synthetic fertilizers tend to have better NUE. The research also highlights that the NUE of cropping systems has decreased globally over the past 50 years, with a significant drop from 68% in the early 1960s to 45% by 1980, followed by stabilization around 47% in recent years. The study shows that synthetic fertilizers are now the largest source of nitrogen inputs to cropland, while manure and biological nitrogen fixation contribute less. The findings suggest that improving agronomic practices and integrating crop and livestock systems can enhance NUE. Additionally, increasing the contribution of symbiotic nitrogen fixation could further improve NUE. The study also identifies that some countries, such as those in Africa and parts of Asia, have low NUE and high nitrogen surpluses, indicating unsustainable nitrogen mining. Overall, the research underscores the need for improved nitrogen management to reduce environmental impacts and enhance agricultural productivity.This study examines 50-year trends in nitrogen use efficiency (NUE) of world cropping systems, focusing on the relationship between crop yield and nitrogen input to cropland. Using data from the Food and Agriculture Organization (FAO), the research analyzes the trajectories of 124 countries from 1961 to 2009, considering crop yield (expressed in kgN ha⁻¹ yr⁻¹) and total nitrogen inputs (synthetic fertilizers, manure, symbiotic fixation, and atmospheric deposition). The study reveals that while some countries have improved their agro-environmental performance, others have seen increased environmental losses due to excessive fertilization. Countries that rely more on symbiotic nitrogen fixation rather than synthetic fertilizers tend to have better NUE. The research also highlights that the NUE of cropping systems has decreased globally over the past 50 years, with a significant drop from 68% in the early 1960s to 45% by 1980, followed by stabilization around 47% in recent years. The study shows that synthetic fertilizers are now the largest source of nitrogen inputs to cropland, while manure and biological nitrogen fixation contribute less. The findings suggest that improving agronomic practices and integrating crop and livestock systems can enhance NUE. Additionally, increasing the contribution of symbiotic nitrogen fixation could further improve NUE. The study also identifies that some countries, such as those in Africa and parts of Asia, have low NUE and high nitrogen surpluses, indicating unsustainable nitrogen mining. Overall, the research underscores the need for improved nitrogen management to reduce environmental impacts and enhance agricultural productivity.