The nitrogen cycle, historical perspective, and current and potential future concerns / D.R. Keeney and J.L. Hatfield -- Nitrogen transformation and transport processes / Ronald F. Follett -- Importance and effect of nitrogen on crop quality and health / Jèurg M. Blumenthal, David D. Baltensperger, Kenneth G. Cassman, Stephen C. Mason and Alexander D. Pavlista -- Utilization and metabolism of nitrogen by humans / Jennifer R. Follett and Ronald F. Follett -- Nitrate losses to surface water through subsurface, tile drainage / G.W. Randall and M.J. Goss -- Nitrogen in groundwater associated with agricultural systems / Michael R. Burkart and Jeffrey D. Stoner -- The importance and role of watersheds in the transport of nitrogen / T.J. Sauer, R.B. Alexander, J.V. Brahana and R.A. Smith -- Nitrogen transport and fate in European streams, rivers, lakes and wetlands / B. Kronvang, J.P. Jensen, C.C. Hoffmann and P. Boers -- Nitrogen effects on coastal marine ecosystems / John R. Kelly -- Gaseous nitrogen emissions from livestock farming systems / Oene Oenema, Andrâe Bannink, Sven G. Sommer and Gerard L. Velthof -- Exchange of gaseous nitrogen compounds between terrestrial systems and the atmosphere / A.R. Mosier -- The impacts of nitrogen deposition on forest ecosystems / K.J. Nadelhoffer -- On-farm technologies and practices to improve nitrogen use efficiency / N.R. Kitchen and K.W.T. Goulding -- Developing software for livestock manure and nutrient management in the USA / Philip J. Hess, Brad C. Joern and John A. Lory -- Field techniques for modeling nitrogen management / Marvin J. Shaffer and Jorge A. Delgado -- Simulated effects of land use, soil texture, and precipitation on N gas emissions using DAYCENT / S.J. Del Grosso, W.J. Parton, A.R. Mosier, M.D. Hartman, C.A. Keough, G.A. Peterson, D.S. Ojima and D.S. Schimel -- Remediation of drinking water for rural populations / W.J. Hunter -- Remediation at the water treatment plant / L.D. McMullen -- Nitrogen management by producers : a multiple scale perspective / Pete J. Nowak, Laurence B. Cutforth, Perry E. Cabot and Bruce M. Kahn -- New policy directions / Andrew P. Manale.