The aim of this study was to determine the concentration and amount of nitrates (NO3 -), ammonium (NH4 +) and mineral nitrogen (Nmin = NO3 - + NH4 +) in precipitation and runoff in six plots in Texcoco, State of Mexico, during the rainy season of 2001 and 2010. For this purpose, six runoff plots with corn cultivation were prepared, three with conventional management (CM) and three with organic management (OM). From 2001 to 2010, average concentrations of NO3 -, NH4 + and Nmin in precipitation increased to 1.307, 0.833 and 2.140 mg·L-1, respectively. Minimum values of NO3 -, NH4 + and Nmin also increased to 0.550, 0.970 and 1.640 mg·L-1, respectively. In runoff, average concentrations of NO3 - in 2001 and 2010 were higher with CM, while concentrations of NH4 + were smaller. Because Texcoco´s population increased by 31,049 from 2001 to 2010, we concluded that population growth and development of the area had an effect on the amounts of nitrogen in precipitation, and that OM was an alternative to reduce nitrogen outputs by runoff.