A Simulation Study On Nitrogen Loss In Paddy Fields Of Erhai Basin Based On DNDC Model

Nitrogen loss in farmland is one of the important factors causing agricultural non-point source pollution,which provides scientific decision-making basis for exploring rational fertilization methods in Erhai basin and for nitrogen reduction and non-point source pollution prevention and control in Erhai basin.Based on experiment,the typical paddy field in Erhai basin was studied,and the nitrogen loss of paddy field under different fertilization treatments was simulated by DNDC model,and the simulation results of DNDC model were verified and analyzed according to the field observation data.Based on the sensitivity analysis function of the DNDC model,the main factors affecting nitrogen loss in rice paddies in Erhai basin and the sensitivity of the simulation results to different factors were studied.The following conclusions were drawn:(1)The DNDC model was simulated and verified by using the measured data of Dali comprehensive test station of the Ministry of Environment of the Ministry of Agriculture and Rural DNDC,which can accurately simulate the surface runoff nitrogen loss of paddy fields under different fertilization treatments,and the correlation is very significant.The results of sensitivity analysis showed that the main factors affecting the surface runoff nitrogen loss in rice field were rainfall and fertilization,among which rainfall was the most sensitive factor,and the larger the surface runoff nitrogen loss in rice field with the increase of rainfall and nitrogen fertilizer application.(2)Using the DNDC model to simulate the leaching nitrogen loss in rice field,it is concluded that the DNDC model can simulate the nitrogen loss in rice field under different fertilization,although there are some deviations,the overall simulation effect is better.Sensitivity analysis showed that the main influencing factors of leaching nitrogen loss i n rice field were rainfall,fertilizer application amount and soil organic carbon content,in which rainfall and fertilizer application amount were positively correlated with nitrogen leaching loss,while soil organic carbon content was negatively correlated.(3)The results show that DNDC model can simulate the accumulation of ammonia volatilization in rice field under different fertilization treatment,and the simulation results are very close to those observed in DNDC field.Sensitivity analysis showed tha t ammonia volatilization in rice field was more sensitive to the influencing factors of soil PH and fertilizer application amount,and the accumulation of ammonia volatilization in rice field increased with the increase of soil PH and fertilizer application amount.(4)This study first introduced the DNDC model into the study of nitrogen loss in paddy field in this region.comprehensive analysis proved that the application of DNDC model simulation to predict nitrogen loss in paddy field in this region is fea sible,and the simulation effect is more accurate.Reducing fertilizer application and increasing organic fertilizer under the premise of ensuring rice yield are effective means to control nitrogen loss in rice field in Erhai basin.(5)Considering the nitrogen loss and rice yield of different organic-inorganic fertilizer application ratio,50% organic fertilizer and 50% chemical fertilizer can effectively reduce nitrogen loss while increasing crop yield,which is an environment-friendly fertilization method for paddy field in Erhai basin.