Key points are not available for this paper at this time.
Peter M. Vitousek, John D. Aber, Robert W. Howarth, Gene E. Likens, Pamela A. Matson, David W. Schindler, William H. Schlesinger, David G. Tilman, Technical Report: Human Alteration of the Global Nitrogen Cycle: Sources and Consequences, Ecological Applications, Vol. 7, No. 3 (Aug., 1997), pp. 737-750
Vitousek et al. (Fri,) studied this question.