Effects Of Efficiency Enhanced Nitrogen Fertilizers On Potato Nitrogen Uptake,and Soil Greenhouse Gas Emission

In potato production,there are problems such as excessive application of nitrogen fertilizer,low fertilizer utilization rate,decreased yield,and environmental pollution.Therefore,it is imperative for potato industry to improve the utilization rate of nitrogen fertilizer and reduce the negative effects caused by nitrogen fertilizer application.Coated nitrogenous fertilizer,nitrogenous fertilizer with nitrification inhibitor or urease inhibitor are considered as enhanced-efficiency fertilizers(EEFs).Application of the EEFs to crop production is one of the effective ways to achieve efficient use of nitrogen nutrients in cropping soil,however,there are few related reports in potato planting system.Therefore,the study of the effect of EEFs on potato yield and nutrient utilization efficiency,and further evaluate its environmental effect and feasibility of extension has significant meaning to development of sustainable potato industry.In the present study,urea and urea ammonium nitrate(UAN)were used as basic nitrogen sources,respectively.Two trials of experiments were carried out under field and greenhouse conditions.The effect of different enhanced-efficiency measures(different EEFs)on potato yield,nitrogen use efficiency and soil nitrogen residue were observed.In trial 1,urea was used as the basic nitrogen source,the treatments were:blank control(no nitrogen fertilizer,CK),urea(Urea),polymer-coated urea,(ESN),urea and nitrification inhibitor dicyandiamide(Urea+DCD),Urea and urease inhibitor n-butyl thiophosphoric triamide(Urea+NBPT)and nitrification inhibitor dicyandiamide(Urea+NBPT+DCD).Trial 2,UAN was treated as basic nitrogen source,the treatments were:blank control(no nitrogen fertilizer,CK),UAN,UAN+NBPT,UAN+DCD,UAN+NBPT+DCD.In addition,under the greenhouse conditions,15N tracer method was used to study nitrogen utilization and transformation of the soil was treated with different EEFs,and greenhouse gas emissions were monitored by laboratory simulation experiment,and the global warming potential was analyzed.The main results are as follows:1.Under field conditions,the nitrogen fertilizers of urea and urea ammonium nitrate all increased yield of potato in different degrees.The highest Increasing yield and efficiency effects were made by the treatment of Urea+NBPT+DCD with urea as the basic nitrogen source,and the treatment of UAN+DCD with UAN as basic nitrogen source,respectively.The EEFs increased the nitrogen fertilizer partial productivity and nitrogen fertilizer agronomic utilization rate of potato,and significantly reduced soil nitrate nitrogen content in soil from 15-60 cm soil layer and soil nitrogen loss.In addition,the results of field experiments were further confirmed under greenhouse conditions.2.The application of 15N tracers in the greenhouse,the addition of combination inhibitors of NBPT+DCD reduced the nitrogen loss,and increased the amount of nitrogen absorbed by plant.3.The laboratory soil experiment showed:The N2O emission cumulative fluxes at the early stage of culture was significantly reduced by different urea EEFs.The cumulative emission of CO2 in the middle and later stage of culture was significantly increased by the treatment of UAN+NBPT+DCD.All EEFs had no significant effect on reducing the global warming potential(GWP).The results of field,greenhouse and laboratory soil experiments indicate that the EEFs significantly reduce soil nitrate nitrogen content and nitrogen loss in soil,increase nitrogen absorption and utilization rate of potato,which further increases potato yield.Meanwhile,the application of EEFs decrease the N2O emissions.Therefore,the EEFs with NBPT and DCD has great application potential in the potato growing system.The method of application of EFFs combining the climate and soil characteristics in different potato produce area deserve further research.