Characteristics of soil nutrients and groundwater pollution of greenhouse vineyards in Qionghai Lake Basin

A typical grape-planting area on the north bank of Qionghai Lake was selected as the research area to reveal the accumulation of nutrients in soil and the pollution characteristics of groundwater in greenhouse vineyards in Qionghai Lake Basin. Surface soil of the greenhouse vineyards and ordinary farmland with different planting years as well as the groundwater in the corresponding area were collected for analysis. The correlation analysis method was applied to explore the relationship between the content of nitrogen and phosphorus in the top soil of vineyards, the physical and chemical properties of soil, and the planting years. The results demonstrated that the average contents of available nitrogen (AN) and available phosphorus (AP) in the surface soil of the study area were 0.702 and 0.135 g/kg, which were 8.2 and 6.5 times of the background (uncultivated) soil, respectively. There was a significant positive correlation between total nitrogen (TN), total phosphorus (TP) concentration and planting years. Both nitrogen and phosphorus accumulated in soil with the increase of planting years, and the accumulation of phosphorus was severe, which was related to the long-term application of phosphorus fertilizer in the process of planting. Meanwhile, there existed a significantly negative correlation between pH and nutrient content in soil of the facility vineyards, and a significantly positive correlation between the soil electrical conductivity (EC) with its nutrient concentration. The large application of nitrogen and phosphorus fertilizer would aggravate the degree of soil acidification and salinization. The nutrient leaching loss in the soil of the facility vineyards was mainly nitrate nitrogen, and the nitrate content in the groundwater increased with the increase of planting years, which posed a potential risk of pollution to the quality of Qionghai Lake.