Accumulation and comparison of greenbelt nutrients under different water irrigating ways

During the research of soil and plants which were irrigated by three types of water(tap water,mixed water of tap and treated water,treated water) in Teda Economic-technological Development Area of Tianjin,the authors analyzed the accumulation of nutrients concentration in soil and plants.Results showed that total nitrogen,organic matter,and pH didn't increase evidently and some of them even had decreasing trend.But hydrolysable nitrogen,available phosphorus and available potassium in soil irrigated by mixed water and treated water increased obviously while the contents of N,P and K in plants changed little.So there is no close correlation between the nutrients in plants and those in soil,which indicates that nutrients in mixed water and treated water are not efficiently used by plants.The study of nutrient content in different soil layers demonstrates that after a long time of irrigation,main nutrients are apt to move downward except organic matter,and there are no significant differences in the three soil layers.