The global agro-food system relies heavily on inorganic nitrogenous fertilizers. In addition to consuming enormous amounts of energy, this manufactured input contributes to the accumulation of reactive nitrogen in the biosphere and undermines the biological basis of agricultural production itself. While technological inefficiency and population may play a role in the phenomenon of global nitrogen accumulation, the social structural features of industrial agriculture must also be examined. The concept of social-ecological metabolism provides an important and needed conceptual framework for engaging global food security issues.