The Reserach On Soil Leaching Of Agricultural Non-point Source Nitrogen Pollution Of Land/Inland Water Ecotone In Baiyangdian Lake

Along with the non-point pollution been gradually control, non-point source pollution has become the main cause of water environment pollution, which agricultural non-point source pollution contribution is the largest. Agricultural non-point source pollution means in agricultural production activities, the soil grain fields such as the nitrogen and phosphorus, nutrients, pesticides and other organic or inorganic pollutants, in precipitation or irrigation process, through the surface runoff,farmland drainage and underground leakage, make a lot of pollution material into the water, causing water environmental pollution.The paper take the NO3-N soil leaching of agricultural non-point source nitrogen pollution of land/inland water ecotone in Baiyangdian Lake as research object, the filed and indoor simulation are used to reserach the land/inland water ecotone soil physical parameters, the influence from soil leaching of agricultural non-point source nitrogen pollution under coupling water and nitrogen , coated controlled/slow-release fertilizers inhibition effect of soil leaching research, the main conclusion showed as follows::1. The determination of land/inland water ecotone soil physical parameters for the agricultural non-point source nitrogen soil leaching provide very important theoretical foundation, and its guidance with science. This paper fitting the ecotone baiyangdian water soil water diffusance and typical farmland soil water characteristic curve. Clear soil water infiltration process and saturated conductivity water rate under the different land use types, in the same soil texture and water supply cases, the original infiltration rate is determined mainly by the soil moist, if start into a deep soil moist, in wet striker is small, the suction gradient infiltration rate lower initial, then infiltration rate also relatively slowly. If the starting of soil dry, suction infiltration is initially infiltration gradient higher, with the time after rate of extended infiltration rate also fast. Soil water infiltration rate: landuse woodland > not landuse woodland > wheat fields> duck farm woodland; Accumulation infiltration: landuse woodland > not landuse woodland > wheat fields > duck farm woodland; Soil saturated conductivity water rate: wheat fields>landuse woodland > not landuse woodland > duck farm woodland.2. Soil nitrogen leaching mainly with soil water infiltration, monitoring the soil moisture content and soil water for irrigation continuous, especially after the period of soil water infiltration, can see the monitoring of the wheat growth season, before the third irrigation, the processing of different soil and soil water potential of soil moisture content is not very obvious differences, and relative from the third irrigation to handle different winter wheat harvest, the soil moisture content of soil and soil water potential difference is increasingly clear. So can determine the wheat growing season the key period of nitrogen leaching is grouting period.3. Through determination the soil profile NO₃-N content of winter wheat before seeding and after harvest , determine 60-90cmand 150-180cm soil profile are soil NO₃-N accumulated layers. Under the condition of different water and nitrogen management ,soil NO₃ - N cumulant changes can be concluded that the cumulant of soil NO₃-N accumulated layer increase with the nitrogen increases and decrease with irrigation frequency increases, high nitrogen application rate and low nitrogen differences between treatment is reduced with irrigation frequency increases, show that NO₃-N leaching into shallow groundwater, NO₃-N leaching with the amount of nitrogen increases.4. Sulfur coated controlled/slow-release fertilizer and coated slow-release urea significantly reduced slow-release urea of soil NO₃-N leaching quantity and effectively control NO₃-N release in early, increase the supply in middle and last Avoid large surpluses crop seeding nitrate leaching, exploiting, improved crop was significantly longer to its absorption of nutrients, satisfying the crops by growth of demand of each nutrient, control the fertilizers produced agricultural non-point source nitrogen pollution.