Study On The Different Fertilizers And Rainfall Intensity Of Phosphorus Losses In The Return Flow Of The Simulated Farmland

In recent years,in order to achieve the high yield,people often invest a lot of fertilizer in the agricultural production,especially the chemical fertilizer.But in the process of growing crops,using of large quantities of chemical fertilizers for the pursuit of high yields not only aggravated the burden of farmland,but also polluted the environment.Under natural conditions,the amount of effective phosphorus in soil is low.Because phosphorus is easily adsorbed in the soil,excess fertilizer is used to ensure that soil phosphate is abundant.The long term and excessive use of phosphorus fertilizer can make the soil chronically rich in phosphorus,and speed up the speed of phosphorus nutrient loss.Through irrigating and rain water,a large amount of phosphorus in the soil enters rivers,lakes and other bodies of water,causing serious pollution of the water and exacerbating its eutrophication.At present,domestic and overseas scholars have carried out a large number of researches on the pollution of agricultural return flow.There are a lot of experimental arguments on the mechanism and model of soil solute movement,but there is no deep research on the migration of pollutants such as nitrogen and phosphorus in agricultural return flow.This experiment mainly study on the change rule of phosphorus concentration in the agricultural return flow of simulated farmland planting pakchoi cabbage,in different condition of rainfall intensity and different kinds of fertilizer.This experiment also provides a theoretical basis and guidance for the research on different kinds of fertilizers in the actual project.This thesis study from the following aspects:1)Study on the use of different kinds of fertilizers have shown that,the difference between total phosphorus,soluble total phosphorus and soluble phosphate concentration in the surface runoff of simulated farmland system,which use organic fertilizer,single-effect phosphate fertilizer and composite fertilizer,is small.The concentration of each form of phosphorus in the non-fertilized surface runoff was significantly less than that of the fertilizer.The results of experimental simulation of farmland surface runoff present that the loss of total phosphorus order is:organic fertilizer>single effect of compound fertilizer>phosphorus fertilizer>no fertilizer,that the loss of soluble total phosphorus order is:single effect phosphate compound fertilizer>organic manure>no fertilizer,that the loss of soluble phosphate order is:single effect phosphate compound fertilizer>organic manure>no fertilizer.The particles phosphorus is the majority of the phosphorus loss in the surface runoff.2)Study on the use of different kinds of fertilizers have shown that,the difference between total phosphorus,soluble total phosphorus and soluble phosphate concentration in the leaching liquor of simulated farmland system,which use organic fertilizer,single-effect phosphate fertilizer and composite fertilizer,is small.The concentration of each form of phosphorus in the non-fertilized leaching liquor was significantly less than that of the fertilizer.The results of experimental simulation of farmland the leaching liquor present that the loss of total phosphorus order is:single effect of compound fertilizer>organic fertilizer>phosphorus fertilizer>no f’ertilizer.that the loss of soluble total phosphorus order is:single effect of compound fertilizer>organic fertilizer>phosphorus fertilizer>no fertilizer,that the loss of soluble phosphate order is:single effect of compound fertilizer>organic fertilizer>phosphorus fertilizer>no fertilizer.The particles phosphorus is the majority of the phosphorus loss in the surface runoff.3)Study on the condition of different rainfall intensity have shown that,in the condition of the rainfall intensity of 50mm/h.80mm/h,100nm/h,the concentration of total phosphorus,soluble total phosphorus and soluble phosphate in the surface runoff of simulated farmland system has extremely significantly positive relation with rainfall intensity.The loss rule of total phosphorus,total phosphorus and soluble phosphate is:the first time rainfall is the largest concentration of phosphorus loss of rainfall,and in the first 3 times rainfall the loss of phosphorus gradually decreases,then the phosphorus loss leveled off after fourth group rainfall.4)Study on the condition of different rainfall intensity have shown that,in the condition of the rainfall intensity of 50mm/h.80mm/h,100mm/h,the concentration of total phosphorus,soluble total phosphorus and soluble phosphate in the leachingJ liquor of simulated farmland system has extremely significantly positive relation with rainfall intensity.The loss rule of total phosphorus,total phosphorus and soluble phosphate is:the phosphorus concentration was gradually increased in the first three rainfall,and loss first time rainfall is the largest concentration of phosphorus loss of rainfall,and the fourth time rainfall is the largest concentration of phosphorus loss of rainfall,then the phosphorus loss decreased after fourth group rainfall.