Effect of long-term fertilization on soil nitrate distribution

A thirteen years long term field fertilizer experiment was conducted to monitor the effect of different fertilization on soil nitrate distribution. The results showed: (1) Applying relative excessive N fertilizer could result large quantities of NO - 3 residue and NO - 3 movement downward in soil profiles; amending phosphate fertilizer or organic manure with nitrogen fertilizer together could significantly improve the status of NO - 3 leaching downward due to the balanced uptake of nutrients by crops. (2) Appropriate amounts of nitrogen fertilizer which was equal or smaller than the optimal fertilization rate could not result in more NO - 3 leaching in Northern China. (3) Precipitation influenced the amounts and depth of soil NO\+-\-3 leaching: NO - 3 could move to 80 cm depth or below at autumn or at the next spring when rainfall was higher during the rainy season through July to September in North China.