| Fuxian Lake is the second deepth lake in China, an well the largest storage capacity lake in Yunnan Province. But in recent years, the water quality has been trended in slow downward, the major source of pollution are agricultural areas and sewage runoff and other non-point source pollution. As the major tourism resources in Yunnan Province and freshwater sources, it is essential to increase the protection and management for Fuxian Lake.Yunnan Province is the largest tobacco-producing areas and the important source of high-quality flue-cured tobacco in our country, it has the area of afforestation about 350,000 hm2, and has above one of the three accounting for the total tobacco production, flue-cured tobacco cultivation is a major economic crops in the Fuxian Lake watershed areas, but almost planting in the slope area.Fertilizer provides the necessary nutrients to crops for growth, but it is also the underlying factors of environmental pollution. Chemical fertilizer plays an important role to improve crops production, but the most of applied farmland fertilizer loss into the water body in the form of surface runoff, which is the important reason for Eutrophication of lakes, so studying the law of soil erosion and nitrogen and phosphorus loss in the slope and finding how to control runoff pollution, is currently an important topic in environmental protection, but also is an important way to protect the lake water in fundamental body.In this study, we choose one of the main watershed entry Fuxian Lake - Jianshan River for study, select one representative slope of flue-cured tobacco in the watershed, take standard runoff plots method, combine with observations of field fertilization experiments, through the continuous observation in 2007-2008 annual runoff and sediment and nitrogen and phosphorus output characteristics, research between rainfall and soil erosion, as well as the different levels of fertilization and fertilization time of flue-cured tobacco under the law of nitrogen and phosphorus loss in slope surface runoff and sediment, in order to provide a theoretical basis to guide the scientific and rational fertilization and evaluation of ground source pollutants exports in slope of flue-cured tobacco correctly and how to control the agricultural non-point source pollution and protect the lakes water bodies. The results show that:(1) Runoff and rainfall have close relationship, runoff has good correlation with the maximum 30-minute rainfall intensity. Runoff and rainfall have the existence of mutual relationship between growth and decline, the beginning of several rainfalls product very little runoff, becouse a long-term have no rainfall, the soil moisture content is too small, and the most of the rainfall is absorb by soil or infiltration into the soil, the resulting is runoff is very low. In the contrary, in June to September the rainfall is more, runoff increases with rainfall is more visible. The pearson correlation coefficient between rainfall and runoff is 0.771 (sig. = 0.000), runoff has a clear linear correlation with the maximum 10-minutes and the maximum 30-minute rainfall intensity, the relationship of runoff (y1) with the maximum 10-minute rainfall intensity (x1) is: y1 = 450.06x1-2033.3, and with the maximum 30-minute rainfall intensity (x2) is: y1 = 793.04x2-1970.8, R2 were 0.7224 and 0.7505, the Pearson correlation coefficients were 0.850 (sig. = 0.000) and 0.866 (sig. = 0.000). So it is clear that the runoff has a better linear correlation with the maximum 30-minute rainfall intensity.(2) Sediment yield with the maximum 30-minute rainfall intensity have a better relationship. Sediment yield has a clear linear correlation with the maximum 10-minutes and the maximum 30-minute rainfall intensity, the relationship of sediment yield (y2) with the maximum 10-minute rainfall intensity (x1) is: y2 = 7.3118x1-81.246, and with the maximum 30-minute rainfall intensity (x2) is:y2 = 13.007x2-81.957, R2 were 0.7249 and 0.7675, the Pearson correlation coefficients were 0.851 (sig. = 0.000) and 0.876 (sig. = 0.000). So it is clear that sediment yield has a better linear correlation with the maximum 30-minute rainfall intensity.(3) NO3- output is the main nitrogen output and PO43- output is the main phosphorus output in runoff. In the year of 2008, the average TN concentration is 5.84mg/L, the average NH4+ concentration is 0.88mg/L, the average NO3- concentration is1.61mg/L, the average of NO3- concentration is about 2 times than the average of NH4+ concentration. The average TP concentration is 0.27mg/L, the average PO43- concentration is 0.22mg/L.(4) Fertilizer significantly affects nitrogen output in runoff and sediment, and affects phosphorus output in sediment significantly, but affects phosphorus output not obvious in runoff. Fertilization for the constant increase of 1.5 times and 2.5 times, the TN concentration in runoff into a constant fertilization of 1.35 times and 1.58 times to 1.14 times the concentration of ammonia and 1.59 times, NO3-N concentrations of 1.21 times, 2.42 times; mud the sand into a constant total nitrogen fertilization, respectively, 1.12 times and 1.19 times to 1.10 times the hydrolysis of nitrogen and 1.24-fold; sediment total phosphorus fertilization, respectively, into a constant 1.05 times and 1.15 times the available phosphorus content to 1.27-fold and 1.69-fold increased significantly; runoff of phosphorus fertilizer Su-output relations and no significant main reason lies in the fact that fertilization of flue-cured tobacco in low-P and P Su-more to the loss of particulate forms, so the relationship is not significant.(5) With the fertilization time passing, N output concentrations decreased in runoff, total nitrogen content in the sediment did not change significantly, but the downward trend in nitrogen hydrolysis Obviously, runoff and sediment are increasing P Su-trend output . Concentration of TN output the highest June 12, June 17 to three fertilization levels decreased by 62.6%, 44.0%, 51.5%, to September 27 level 3 fertilization TN relative to the average level of June 12 fell of 66.1% and 65.9%, 55.9%. Help with the application to extend time, the concentration of TN in runoff decreased, June 12 highest TN content was mainly due to just the near fertilization, fertilizer N The loss of more. Little change in the concentration of ammonia nitrogen output, and basic in the 0.7mg/L fluctuations. Significantly affect the nitrate content. Sediment total phosphorus and available phosphorus content increases with the increase of fertilizer, fertilization with time, sediment total phosphorus content changed little, the basic 0.5-0.6g/kg maintained at between the available phosphorus content appeared to rise high and further lower the trend of rising again. (6) Level-terrace land preparation is an important measure for water and soil conservation in mountain slope, it plays an important role in reduction of nitrogen and phosphorus output and reduces soil erosion. Set the level of order in 2008, the District 17 runoff is limited to the larger market would only occur under conditions of rainfall and runoff coefficient are very small, mainly because of the level of order has played a role of storing the runoff and increase water infiltration, runoff and therefore a sharp decline. The level of preparation can effectively reduce the band slope in the volume of runoff and sediment yield; reduce production volume by 61.9% and the average sediment concentration a decrease of 40.6%, sediment yield decreased by 77.4%. Flow was significantly reduced as a result of production, with run-off losers The nitrogen and phosphorus and other nutrients also significantly reduced output, TN output decreased by 48.35%, a decrease of ammonia nitrogen output of 50.85 percent, a decrease of nitrate output of 56.53%, TP output decreased by 68.82%, PO43 - output decreased by 76.18%. With the loss of sediment nitrogen and phosphorus and other nutrients, the total output decreased by 48.35%, the hydrolysis of nitrogen output decreased by 82.1%, total phosphorus output decreased by 85.8%, available phosphorus output decreased by 67.9%.
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