Study on nitrogen balance by use of 15 N-labeled fertilizer in flue-cured tobacco field

The 15 N-labeled method was used to study the nitrogen balance in flue-cured tobacco field. The results showed that although the production of fluecured tobacco was increased with the addition of the nitrogen fertilizer, the utilization rate of nitrogen fertilizer was decreased gradually. Nitrogen was mainly distributed in the stems and leaves of the flue-cured tobacco, and went up gradually with the increase of nitrogen fertilizer. Generally, with the increase of nitrogen fertilizer, the proportion of fertilizer-N in roots, stems, buds and terminal buds first increased and then decreased, however, it basically showed the increasing trend in leaves. The loss of nitrogen (runoff, seepage and sediment) and wastage nitrogen (other ways) mainly came from soil-N with the increase of nitrogen fertilizer rate. The increase of nitrogen fertilizer rate aggravated the loss of nitrogen, increased the surplus of soil nitrogen, and reduced the recycling rate of nitrogen. Considering the yield, quality and nitrogen utilization rate comprehensively, T8 (120 kg/ hm 2 ) showed the best nitrogen fertilizer rate in this experiment. 15 N fertilizer, nitrogen fertilizer rate, nitrogen balance.