The Effects Of Tillage Measure On Nitrogen And Phosphorus Balance In Sloping Farmland Of Black Soil Region

The sloping field in the black soil region is widely distributed,and the unreasonable development and utilization cause the soil nutrient imbalance and a large area of agricultural non-point source pollution.Therefore,under the different management measures of tillage,investigating the loss of nitrogen and phosphorus nutrients,analysis of nitrogen and phosphorus nutrient balance in sloping field have a great significance for protecting the black soil resources and water ecological environment.In this thesis,the corn sloping field in black soil region was taken as the research object,and 14 kinds of tillage measures were set up.The concentration and total loss quantity of the nitrogen and phosphorus in the surface runoff and sediment,as well as the nitrogen and phosphorus uptake of maize in the seeding stage of maize after large scale rainfall were studied.The changes of soil nitrogen and phosphorus nutrient contents pre-and post-rainfall and the balance of nitrogen and phosphorus were also analyzed.Finally,the best tillage measures suitable for corn sloping field in black soil region were selected.The main results are as follows:In surface runoff,NH₄-N concentration was higher,NO₃-N and PO₄-P concentrations were relatively low.The effects of 14 tillage measure on them were basically same.Horizontal ridge?HR?measures and residue coverage?RC?increased the concentration of NO₃-N,NH₄-N and PO₄-P.However,the runoff flow rate were reduced due to the conditions of HR and RC,so the total loss quantity of soil nitrogen and phosphorus decreased.The total loss of NO₃-N,NH₄-N and PO₄-P under the HR+RC were 2.95mg/m²,19.89 mg/m² and 0.11 mg/m² respectively,which were 7.69%,7.45%and 6.67%of the control?fallow land?.In the sediment,NO₃-N and PO₄-P concentrations were higher,NH₄-N concentration was relatively lower,which are in contrast with the results of runoff.The concentrations of NO₃-N,NH₄-N and PO₄-P under the treatment of HR were the highest.The total loss of NO₃-N,NH₄-N and PO₄-P were the 0.01 mg/m²,0.00mg/m² and 0.01 mg/m² under the treatment of HRM+RC which was the best measure to reduce the loss of nitrogen and phosphorus in the sediment.About the balance of nitrogen and phosphorus,soil nitrogen and phosphorus were mainly lost with surface runoff,and the contribution rate of sediment carry was low under the condition of fallow land.And in terms of maize,the soil nitrogen and phosphorus were mainly absorbed by the maize,the contribution rate of sediment and runoff was low.