Abstract: STUDY ON FORMATION AND ACCUMULATION OF SOIL NITRATE INFLUENCED BY FERTILIZER NITROGEN WITH ~(15)N TRACING TECHNIQUEGuo Zhifen;Pan Yong;Tu Shuxin;Zhang Yichun;Lin Ruotai(Institute of Atomic Energy in Agricultural Use,Hubei Academy of Agricultural Sciences.Wuhan 430064)Abstract:By using 15N tracing technique,the drnamic change of soil nitrate from fertilizer N and its influence to soil nitrate accumulation are studied through pot experiments under usual cultivating condition.The results show that the dynamic changes of net amount of formed and accumulated nitrate from fertilizer N(NDFF)in soil with different fertilities, under different amount of N fertilizer,and in different ratios of basal and split application,accord with the mathematicc model: Nt=atebt.NDFF increase linearly along with the increase of the amount of N fertilizer. The peak of soil nitrate content appears synchronously with the peak of soil NDFF.It shows that NDFF is the major factor causing high content of soil nitrate.The ratio of hasal and split dressing of N fertilizer 8: 1: 1 is better than 6:2:2.Heavy amount of hasal N fertilizer not only supply sufficient N nutrient for vegetable growth, but the decrease the nitrate content of vegetable during harvest.The maximum nitrification ratio of fertilizer N in soil is up to 20%-42%, according to the soil fertility and rate of fertilizer N applied.Keywords:~(15)N tracing nitrate formation accumulation nitrification ratio