鄱阳湖流域种植系统氮磷通量时空变化及减量潜力OA

In recent years,the excessive input and inefficient utilization of nitrogen and phosphorus in cropping systems has led to significant losses of these elements.Lake Poyang Basin has led to significant losses of these elements,resulting in persistent nitro-gen and phosphorus levels exceeding the legal limit,as well as other environmental issues.Therefore,tracing the spatiotemporal patterns of nitrogen and phosphorus metabolism in the Lake Poyang Basin cropping system is crucial for ensuring the basin's ecosys-tem sustainability.This study used the material flow analysismethod to investigate the spatiotemporal variations in nitrogen and phosphorus fluxes in cropping systems across the Lake Poyang Basin from 2000 to 2022.Four scenarios were designed based on the current status of nitrogen and phosphorus pollutant emissions:a baseline scenario,a scenario with reduced fertilizer inputs for ara-ble land,a scenario with increased straw recycling rates,and a scenario with comprehensive measures.The emission reduction po-tential was calculated for each scenario,and the optimal strategies for reducing and preventing nitrogen and phosphorus pollution were then proposed.The results show that nitrogen and phosphorus inputs to the basin initially increased and then fluctuated stab-ly,peaking around 2015.In terms of spatial distribution,the total nitrogen and phosphorus inputs were highest in the coastal lake district,reaching 281000 t of nitrogen and 64000 t of phosphorus,respectively.Chemical and organic fertilizers accounted for over half of the total inputs.In terms of nutrient use efficiency,the combined use rates of nitrogen and phosphorus were 48.5％and 31.0％,respectively.Since 2010,the utilization rates of nitrogen and phosphorus for all crops have declined,as has the ratio of nutrient inputs of nitrogen and phosphorus,with an average N/P ratio of 3.9.Scenario analysis suggests that reducing chemical fertilizer use could decrease nitrogen output by 150000 t by 2050 and reduce nitrogen and phosphorus emissions by 159000 t/a,which would reduce pollutants by 53.4％.Compared with the baseline scenario,the N/P ratio discharged into the environment could rise to 6.5.Reducing fertilizer application accounts for 75.7％of the emission reduction,demonstrating its effectiveness as a mitigation strategy.This study provides a scientific basis for developing effective,integrated nitrogen and phosphorus management measures in the Lake Poyang Basin,and evaluating the potential outcomes of future scenarios.