The Study On Regularity Of Nitrate Accumulation In Greenhouse Soil And Vegetables

With the people's attention to the quality and safety of vegetables, nitrate in vegetables and soil and the pollution research the law attracted widespread attention. Nitrate is the main source of plant nitrogen, in most cases is the high quality of vegetables a positive factor. However, in nitrate-rich vegetable products easy, especially in the highly intensive cultivation of the facilities, the relatively confined, continuous fertilization, even for a high degree of cultivation, so as to enable a large number of the accumulation of soil nitrate, soil nitrate was absorbed and used vegetables, the enter the body through the food chain, to bring potential harm to human health. Therefore, how to reduce nitrate pollution of vegetables has become a hot issue to be settled urgently.By the investigation of Shouguang soil nutrients and the nitrate content, this study analyzed the nitrate content of different cultivation years and soil nutrients influence on soil nitrate; and studied the form and amount of nitrogen fertilizer and fertilizer of combination on nitrate content in soil and vegetable in Shandong Provincial Academy of Agricultural Sciences by field experiments and pot experiment; and studied the crop stubble to reduce the role of soil nitrate content by field experiments in Shouguang, provided theoretical basis for addressing the nitrate pollution in soil, the results were as follows:1. The nitrate in greenhouse was relatively high, nitrate with the increase of cultivation period of gradual increase in content, and gradually reduce in 0~60cm, but the content of nitrate in soil surface is highest. Available nitrogen and Water-soluble salt had positive impact on nitrate, but pH had negative impact.2. Nitrate in soil and cucumber had significant positive correlation with the amount of nitrogen; from the production point of view, the nitric nitrogen fertilizer was the highest, followed by urea, ammonium nitrogen state was minimum; the treatments of nitric nitrogen fertilizer had the most nitrate in soil and cucumber fruit , followed by urea, ammonium nitrogen state was minimum; Vc content in the treatment of ammonium nitrogen state was highest, followed by urea, the nitric nitrogen treatment was lowest.3. Fertilizer of combination tended to give better yields and fruit quality, yield of organic manure as fertilizer. Nitrogen and phosphate fertilizer, potash fertilizer could reduce nitrate content in cucumber ,potash fertilizer was the best, and organic fertilizer also significantly reduce the cucumber and soil nitrate content. Throughout the growth period, the accumulated phosphorus in reducing nitrate on the early better than late, and the effect of potassium in the middle and late is better than early.4. After the adoption of crop cultivation can significantly reduce soil nitrate content, specially the 0-20cm soil.5.Considering the nitrate content of cucumber fruit, quality and production, as well as factors such as soil nitrate accumulation, urea was the best in the three kinds of nitrogen fertilizer. Nitrogen fertilizer should not exceed 675kg/hm2 through the field experiments of nitrogen fertilizer application, however should not exceed 0.4g/kg(675kg/hm2) through pot experiment, the study can be concluded nitrogen fertilizer should not exceed 675kg/hm2, Nitrogen combinated with phosphate fertilizer, potash fertilizer, and taking reasonable cropping patterns could reduce the nitrate content of soil and cucumber.