Abstract:In Shouguang, as a Chinese-famous production area of protected-land vegetables, the phenomenon of excessive fertilization is very common. To investigate nitrate-nitrogen (nitrate-N) variations of groundwater in intensive greenhouse-vegetable farmlands of Shouguang, a continual site-directed survey on farmland irrigation and countryside drinking wells was carried out under two different agricultural cropping systems. The cropping systems studied were wheat-corn cropping field and the greenhouses of annual two-stubble tomato during 2003-2005. The results suggested that with the passage of time, the variation of nitrate-N content was little in the main-field groundwater, and no exceeding limit was observed on the nitrate contents in drinking water of the countryside. However, in the greenhouse area, nitrate-N content in the well for irrigation during a year (from the beginning to the end) indicated the significant increasing tendency, and further more the annual change was regular and increasing. The average value of nitrate-N content in irrigation water was higher than in drinking water,and in shallow groundwater was obviously higher than in deep groundwater. Whether in the greenhouse area or main field area, the different well depth had great effect on nitrate-N content, that is to say,nitrate-N content in shallow wells was obviously superior to that in deep wells. The phenomenon of nitrate-N over standard was very common in countryside drinking water of greenhouse areas, and the maximum nitrate contents reached to 45.60 mg·L-1, and compared with Chinese drinking water standard (20 mg·L-1), the ratio of exceeding standard was up to 37.50% and average at 1406%; as for drinking water upper limit recommended by world health organization (WHO), the ratio of exceeding standard reached 56.25% and average at 42.19%. It was concluded that cultivation pattern of intensive greenhouse vegetables resulted great pollution of nitrate-N to countryside groundwater, and the high nitrate content in the drinking water has composed a potential threat to the health of local population. Our results have good significance in the field of modern eco-friendly approaches in pollution ecology.