The United States Department of Agriculture (USDA) defines soil health as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans, and healthy soil gives us clean air and water. Nitrogen is indispensable to support life on earth, including for food production, but it also causes environmental problems such as global warming and groundwater pollution. This book brings together novel aspects of soil nitrogen research that solve these problems, with a particular focus on soil health in intensive agricultural systems. The two main sections are: 1) Monitoring and understanding of soil nitrogen transformations to maintain soil health, and 2) Soil nitrogen management for soil health. Included topics are regulation of key nitrogen loads and processes such as nitrous oxide emissions, nitrate leaching, ammonia volatilization, denitrification, nitrogen fixation, nitrification, mineralization, their relationships with the soil microbial biomass, and impact of soil management practices for enhanced soil health and sustainability. This book includes selected papers presented at the symposium Nitrogen Cycling and Soil Health at the 2022 World Congress of Soil Science, which took place in Glasgow, U.K.