Leaching and transport of nitrate in vegetable production systems in Suburbs of Wuhan

The nitrate（NO3-）contents of vegetable field soil, soil solution and well water were annually determined in suburbs of Wuhan, where are the typical open-air vegetable production systems. The results show that the average NO3--N content in 0-100 cm soil is 11.2 mg/kg and the content in 0-20 cm soil is 21.1 mg/kg. The NO3- content in soil solution at 60 cm depth is 27.5 mg/L, and the NO3--N concentrations in well water are from 19.6 to 39.8 mg/L. These results indicate that the nitrate leaching loss is serious in the vegetable soil, and the NO3--N content in well water is far more than the safe standard for drinking water. The amount of nitrate leaching loss has a direct relationship to the amount of nitrogen fertilizer and water input, the growth situation of vegetable crops and soil particle composition. Due to different soils have different particle composition, especially for the sandy soil, the groundwater may have suffered serious nitrate pollution although the crops could grow normally. This study could make contributions to scientific evaluation of the nitrate pollution of open-air vegetable field soil and groundwater.