Studies On Agrochemicals Input And Nitrate Pollution In Groundwater In Intensive Vegetable Cultivated Area

Through farmer household survey, statistic analyzing and groundwater monitoring, this dissertation made a systematical study on the agrochemical input and nitrate pollution in groundwater. The study includes three levels on region, vegetable cultivation pattern and typical vegetable variety. The main purpose of the research is to show the agrochemical-input level and to evaluate actual groundwater nitrate polluation in Shouguang county Shandong Province.(1) The fertilizer and pesticide input rates are increasing year by year. Nitrogen fertilizer input rate has little increase, while compound fertilizer input rate increases remarkably every year.(2) The fertilizer input rate (nutrient) in intensive vegetable culture areas is 5368.4kg/hm², which is very high, and N amount to 2017.0kg/hm², N: P₂O₅: K₂O is 1: 0.9: 0.76. Though N and P₂O₅ inputs are still high and K₂O input have had a great increment, K₂O input still should be increased. The pesticide input amount to 137.5kg/hm², while 24.4% is insecticide, 75.6% is fungicide.(3) Vegetable cultivation patterns are different, and the fertilizer and pesticide inputs are different, too. The fertilizer input rate in a year of the two cultivation pattern is in the order sunlight greenhouse> small plastic tunnel. The pesticide input rates of the sunlight greenhouse of spring vegetable and winter vegetable are similar, but the pesticide input of small plastic tunnel of spring vegetable is higher than that of winter vegetable. The pesticide input of spring vegetable is as 2.4 times as that of winter vegetable.(4)The fertilizer input rate of spring vegetable is aubergine > cucumber > tomato > leek and tomato> cucumber > aubergine > leek in that of winter vegetable. In general, the fertilizer inputs of spring vegetable are higher than that of winter vegetable. And N input rate of spring vegetable is higher than that of winter vegetable except tomato. Pesticide input of tomato in spring is lower than that in winter, while pesticide input of aubergine, cucumber are increased little compared with that in winter, and pesticide input of leek is much higher than that in winter.(5) The analysis of 653 groundwater samples sampled on 2003.9, 2003.12, 2004.4, 2004.7 respectively in the intensive vegetable cultivated area shows that the groundwater nitrate pollution in Shouguang County is serious. The average nitrate concentration of all samples is 21.66 mg/L, about 54.36% of the samples exceed 11.3 mg/LNO)₃^- —N.(6) It was testified that the nitrate concentration of groundwater has a positive correalation with N input rate and planting years, and is negative with the depth of well.