Study On Environmental Effect Of Different Planting Patterns For Riverhead Protect Region Of Huangpu Upriver

In recent years, planting patterns of farmland in our country have changed greatly along with the adjustment of cropping system. While in different planting patterns the fertilizer application rate and nutrient balance differ a lot from each other. In order to guide agricultural production and decrease agricultural environmental pollution, the environmental effect and nutrient balance condition of different planting patterns are studied in this research. Totally 35 pieces of fields and 37 kinds of plants in the valley of Huangpujiang river in Shanghai are investigated. This work also studys the nutrient absorption law of main plants and the nutrient balance condition of main planting patterns in Shanghai. Rainfall and other meteorology condition are combinated in analysing the environmental effect of different planting patterns. The main result are as fellows:Sampling in main growing stage in every crop,this work studys the N,P,K absorption law of solanacecus fruit, gourd crop, leguminous vegetable, leaf vegetable, seedling and several other plants.The current situation of nitrate concentration of vegetable in Shanghai: the content of nitrate in vegetables varied significantly with different categories of vegetable species, the order is leaf vegetable>root vegetable>scallions>cauliflower>leguminous vegetable>solanacecus fruits>gourds crop> Chinese ram; late harvest can reduce nitrate concentration of vegetable in some degree.The amount of nitrogen fertilizer influences nitrate content of vegetables.Different planting patterns have significant effects on soil available nutrient contents. Soil available N,P contents for vegetable and fruit tree are obviously higher than those of seedling and grain crops. The content of N,P,K in different soil depth also varied apparently. Content of TN ,TP ,OM, NH4+-N, NO3--N, AP decrease from top soil to the deeper layer of soil in the 0-90cm soil profile, but content of AK increase slightly from top soil to deeper layer of soil.The result of nutrient balance condition of different planting patterns is listed as follows. N surplus for grain crop is 78.9 kg.ha-1.a-1, P(P2O5) and K(K2O) deficit are 38.1kg.ha-1.a-1 and 169.8kg.ha-1. a-1.N, P2O5 surplus for vegetable are 181.1 kg.ha'.a"1 and 101.7kg.ha-1.a-1, K2O deficit is 66.\kg.ha-1.a-1. N,P(P2O5),K(K2O) surplus for fruit tree are 404.7kg.ha-1.a-1,118.5kg.ha-1.a-1 and 147.0kg.ha-1.a-1. N, P(P2O5),K(K2O) for seedling are surplus slightly, but compared with fruit tree and vegetable, surplus amount of N and P(P2O5) is little.Nutrient balance conditions in a year have significant difference in different crop rotations. N surplus, P surplus or balance, K deficit exsit in crop rotations of grain crops. While the nutrientbalance condition for crop rotation of vegetable crops varied significantly.Taking fertilizer, rainfall and vegetation mulching period into account, environmental effect of different planting patterns in the valley of Huangpu river in Shanghai is preliminarily analyzed. The results shows: some crops have friendly entironmental effect,such as potato, Buxus microphylla and so on.,but other crops have bad entironmental effects, such as ZizanizLatifolia, cucumber and so on.