Book excerpt: The production of food and energy interfere with the natural nitrogen cycle of the earth. Many of these changes are beneficial, while others are detrimental to societies and the environment. The changing nature of nitrogen in the global environment crosses scientific disciplines, geographical boundaries and political divisions and challenges the creative minds of natural and social scientists, economists, engineers, business leaders and planners. The papers in this book give readers a panoramic view of the changing nature of reactive nitrogen in the global environment, enabling them to make better choices about nitrogen management in food production and consumption, energy production and use, and environmental protection.