Human Contributions to Terrestrial Nitrogen Flux

This article assesses the sources and fates of anthropogenic fixed nitrogen. Anthropogenic nitrogen from most sources comes together in the common pathways of the agricultural food chain. The topics covered in this article include the following: inputs of newly fixed nitrogen; nitrogen flow in agriculture; calculating production of plant nitrogen; calculating consumption of nitrogen; harvests and grazing and the effect on nitrogen; nitrogen flow through livestock; net trade; nitrogen flows in regions of the United States; riverine discharges. 51 refs., 4 figs., 4 tabs.