Rational application of different forms of nitrogen(N) fertilizer for peanut(Arachis hypogaea L.) requires tracking the N supplied sources which are commonly not available in the differences among the three sources:root nodule,soil and fertilizer.In this study,two kinds of peanut plants(nodulated variety(Huayu 22) and non-nodulated variety(NN-1)) were choosed and four kinds of N fertilizers:urea-N(CONH_2-N),ammonium-N(NH_4~+-N),nitrate-N(NO_3~--N) and NH_4~+ +NO_3~--N labeled by~(15)N isotope were applied in the field barrel experiment in Chengyang Experimental Station,Shandong Province,China,to determine the N supplied sources and N use efficiency over peanut growing stages.The results showed that intensities and amounts of N supply from the three sources were all higher at middle growing stages(pegging phase and podding phase).The accumulated amounts of N supply from root nodule,soil and fertilizer over the growing stages were 8.3,5.3 and 3.8g m~(-2) in CONH_2-N treatment,which are all significantly higher than in the other three treatments.At seedling phase,soil supplied the most N for peanut growth,then root nodule controlled the N supply at pegging phase and podding phase,but soil mainly provided N again at the last stage(pod filling phase).For the whole growing stages,root nodule supplied the most N(47.8 and 43.0%) in CONH_2-N and NH_4~+-N treatments,whereas soil supplied the most N(41.7 and 40.9%) in NH_4~+ +NO_3~--N and NO_3~--N treatments.The N use efficiency was higher at pegging phase and podding phase,while accumulated N use efficiency over the growing stages was higher in CONH_2-N treatment(42.2%) than in other three treatments(30.4%in NH_4~+-N treatment,29.4%in NO_3~--N treatment,29.4%in NH_4~+ +NO_3~--N treatment).In peanut growing field,application of CONH_2-N is a better way to increase the supply of N from root nodule and improve the N use efficiency. Rational application of different forms of nitrogen (N) fertilizer for peanut (Arachis hypogaea L.) requires tracking the N supplied sources which are commonly not available in the differences among the three sources: root nodule, soil and fertilizer. In this study, two (nodulated variety (Huayu 22) and non-nodulated variety (NN-1)) were choosed and four kinds of N fertilizers: urea-N (CONH_2- , nitrate-N (NO_3 ~ --N) and NH_4 ~ + NO_3 ~ --N labeled by ~ (15) N isotope were applied in the field barrel experiment in Chengyang Experimental Station, Shandong Province, China, to determine the N supplied sources and N use efficiency over peanut growing stages. The results showed that intensities and amounts of N supply from the three sources were all higher at middle growing stages (pegging phase and podding phase). The accumulated amounts of N supply from root nodule, soil and fertilizer over the growing stages were 8.3, 5.3 and 3.8 gm ~ (-2) in CONH_2-N treatment, which are a A significantly higher than in the other three treatments. At seedling phase, soil supplied the most N for peanut growth, then root nodule controlled the N supply at pegging phase and podding phase, but soil mainly provided N again at the last stage (pod filling For the whole growing stages, root nodule supplied the most N (47.8 and 43.0%) in CONH_2-N and NH_4 ~ + -N treatments, while soil supplied the most N (41.7 and 40.9%) in NH_4 ~ + + NO_3 ~ --N and NO_3 ~ --N treatments. The N use efficiency was higher at pegging phase and podding phase, while accumulated N use efficiency over the growing stages was higher in CONH_2-N treatment (42.2%) than in other three treatments (30.4% in NH_4 ~ + -N treatment, 29.4% in NO_3 ~ --N treatment, 29.4% in NH_4 ~ + + NO_3 ~ --N treatment) .In peanut growing field, application of CONH_2-N is a better way to increase the supply of N from root nodule and improve the N use efficiency.