Characteristics Of Nitrogen And Phosphorus Losses In Banchengzi Reservoir Watershed Under Different Land Use

The loss of soil nitrogen and phosphorus is the main form of agricultural non-point source pollution and the main source of water eutrophication.Under the combined influence of climatic factors and irrational use by humans,soil erosion in the basin during the flood season is serious.Fertilizers,nutrients and other nutrients and silt carried by soil erosion have become one of the main sources of pollution of rivers and reservoirs.This study took Banchengzi Reservoir in Miyun County,Beijing as the research area,and selected corn field 1(terraced field measure),corn field 2(slope farmland),chestnut forest(horizontal strip measure),pasture(artificial planting),and natural vegetation 1.(Fish-scale pit measures),natural vegetation 2(no measures),bare land and other seven different land use methods,conduct runoff,sediment and nitrogen and phosphorus loss characteristics research.On this basis,the loss of nitrogen and phosphorus in corn fields,chestnut forests,pastures,natural vegetation and bare land in the Banchengzi Reservoir watershed was measured,and laboratory experiments on soil dissolution under different land use methods were carried out.The main research conclusions are as follows:(1)Studies on the relationship between effective rainfall and runoff and sediment yield during the flood season from 2017 to 2018 show that runoff and sediment loss under different land use methods generally increase with the increase in rainfall.Among them,the runoff and sediment loss of bare land and corn fields are relatively high,and the runoff and sediment loss of pasture grassland and natural vegetation are relatively low.Engineering measures such as terraces,horizontal strips and fish scale pits have all played a role in reducing runoff and sediment loss.(2)Under natural rainfall conditions,the loss of total nitrogen and total phosphorus in different land use methods increases with the increase of rainfall.Among them,the nutrient loss concentration of corn field and chestnut forest is higher,and the nutrient loss concentration of natural vegetation and pasture grassland is lower.The loss of nitrogen and phosphorus in soil nutrients increases with the increase in runoff and sediment loss,and the loss of total nitrogen and total phosphorus has a significant relationship with runoff and sediment loss.(3)Soil nutrient loss calculation and dissolution experiment of different land use in Banchengzi Reservoir basin.Corn fields and chestnut forests have a greater impact on the water quality of Banchengzi Reservoir.The dissolution concentration of total nitrogen and nitrate nitrogen in different land use methods is significantly higher than the dissolution concentration of total phosphorus.The dissolution content of total phosphorus in corn field is higher.The soil nutrient loss in the chestnut forest and natural vegetation with engineering measures is obviously less during the flood season.