The dynamics of soil nitrate nitrogen leaching and contamination of the groundwater in high-yield farmland

The field scale investigation reveals that in high-yidd farmlands where the managements of the irrigation and fertilization are diferent in Huan tai County of Shandong Province．The dynamics of nitrogen leacNng and the groun dwater pollution quite differ from each other．Soil content of NO₃^--N keeps decreasing after spring and its concentration of NO₃^--N in thegroundwater correspondingly increases gradually．The concentration in the groundwater dramatically changes and reaches the maximum after the raining season，demonstrating that the direct contamination results from the nitrogen fertilization．This is probably related to the more irrigation，lighter soil texture and shallower groundwater in this area．