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Based on vegetable cultivation in Dianchi Lake Basin nutrient losses to water pollution worsening environmental situation in order for lettuce and loose leaf lettuce planting process for nutrient management-based differences in effects of different levels of nitrogen and phosphorus crop yield, nitrate content, nitrogen and phosphorus nutrient utilization, soil nitrogen and phosphorus, organic carbon and nitrogen and phosphorus cycling farmland ecosystem characteristics and balance in order to find an appropriate level of nitrogen and phosphorus application, designed to ensure farmers' economic, while achieving environmental benefits maximized, thereby effectively mitigation of agricultural nonpoint source pollution in Dianchi Lake Basin nitrogen and phosphorus pollution load. The main results show that: 1. Nutrient diversity management, the optimum range of nitrogen fertilizer, crop yield increases with the amount of nitrogen increased, when excessive nitrogen fertilizer, yield increase effect was not significant, and even cause cuts. T3 (N90P126K180) handling lettuce production is relatively high, reaching 28968.75kg · ha-1, while the loose leaf lettuce in the T5 (N848P316K792) with the next higher yield reached 47373kg · ha-1. Phosphate Fertilizer season for both crop yield does not produce a significant impact. 2 different growth stages, crop utilization of both nitrogen and phosphorus elements are much lower than our average utilization levels. In phosphorus and potassium quantitative conditions, excessive application of nitrogen fertilizer, is not conducive to improving nitrogen use efficiency of crops, but increases the likelihood of nitrogen nutrient loss. At the same nitrogen (phosphorus) levels of processing, the corresponding phosphorus crop nutrient utilization overall downward trends. 3 lettuce planting soil nitrogen, phosphorus, nitrogen and available phosphorus content in the vertical gradient layer by layer showed decreasing trend. Different growth stages, each different soil treatments nitrogen, phosphorus content showed irregular variations, harvest, soil surface nitrogen (nitrogen), available phosphorus, respectively, and seasonal application rate, the amount of phosphorus exhibit correlation, growing, surface total phosphorus content and seasonal phosphate levels positively correlated. 4 loose leaf lettuce growing areas of soil total nitrogen, available phosphorus and nitrogen content, vertical section showing consistent with the law of lettuce. However, there have been some downward movement of phosphorus treatment of the phenomenon. The harvest period, with the nitrogen fertilizer increased soil surface nitrogen showed overall increasing trend, soil surface nitrogen content and seasonal nitrogen scales emerged correlation. Available phosphorus mainly in 0-40cm soil layer. 5 two growing areas of vertical changes of soil organic carbon content expressed as 0-20cm gt; 20-40cm gt; 40-60 cm. All processing topsoil organic carbon content is higher than the other two layers. Lettuce and loose leaf lettuce growing areas is the highest organic carbon T6 (N406P0K633) and T4 (N565P316K792) treatment, respectively 156.75t.ha-1, 116.12 t.ha-1. 6. Nitrogen and phosphorus from farmland ecosystem cycling and balance characteristics of the soil phosphorus than nitrogen residues residues, each treatment of nitrogen, phosphorus absorption input can meet the demand for crop growth, high nitrogen and phosphorus fertilization (T5 and T8), the corresponding nitrogen and phosphorus Su surplus amount is generally higher than the rest of the nitrogen and phosphorus fertilization treatments prime surplus amount. 7 Considering the differences in nutrient management on crop yields, loss of nitrogen and phosphorus to determine the optimum nutrient management, environmental and economic benefits in order to achieve unity. The results show that with the loose leaf lettuce lettuce optimal fertilization treatments were T6 (N406P0K633), T3 (N282P316K792) processing.
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