Abstract:Nitrogen application is one of the most important measures to increase yield and improve quality in ginger production.However,misuse of N fertilizer not only decreased N use efficiency but also caused environment pollution.Many studies found that humic acid could accelerate growth of crop root and increase fertilizer use efficiency.But there were few researches about the relationship between the effects of humic acid on crop and fertilizer utilization rate.So this study was conducted to determine the effects of humic acid fertilizer on N absorption,assimilation of ginger and N use efficiency,to provide theory basis for the research and application of humic acid fertilizer.A pot culture experiment was carried out on the agricultural experiment station of Shandong Agriculture University to study the effects of humic acid urea on yield and N absorption, assimilation and quality of ginger using 15N tracer technique.Five treatments (T1,T2,T3,T4,T5) were set up and each treatment had 30 pots.Six pots of each treatment(T3,T4,T5) were used for 15N tracer experiment.The results showed that humic acid urea application increased fresh weight and vigor of ginger root.15N tracer experiment showed that humic acid urea application increased N use efficiency significantly.Meanwhile,it increased N uptake from soil.Humic acid urea application increased NR activity,which increased N content and accumulation in ginger plant and increased the proportion of N allocation to rhizome.Humic acid urea application increased protein content and protein production of ginger rhizome significantly.In addition,humic acid urea application improved ginger quality through increasing gingerols and decreasing NO3- content.