Abstract:

【Objective】 The objective of this study is to understand the dynamics of nitrogen from organic matter during the tobacco growing process and its contribution of organic fertilizer nitrogen to nitrogen nutrition of flue-cured tobacco and to provide a basis for rational fertilization of the flue-cured tobacco. 【Method】 The rapeseed fertilizer, rice straw and rape straw were studied by 15N tracer.【Result】 The nitrogen utilization efficiency of rapeseed cake, rice straw and rape straw were 19.5%, 15.5% and 8.1%, respectively, and the inorganic fertilizer nitrogen utilization efficiency were 41.1%, 42.7% and 35.7% under combined application of organic additives and inorganic nitrogen fertilizer. The contribution rate of rapeseed cake, rice straw, rape straw to accumulated nitrogen of flue-cured tobacco were 1.0%, 2.4% and 2.7%, respectively, by the combined application of organic additives and nitrogen fertilizer. The contribution proportion of rapeseed cake, rice straw and rape straw after top pruning was 4.4%,20.8%, and 18.9% to accumulated nitrogen of flue-cured tobacco, respectively. 【Conclusion】 The results demonstrate that the contribution of rapeseed cake, rice straw and rape straw to nitrogen nutrition of flue-cured tobacco is very low and the absorption of flue-cured tobacco for organic nitrogen accord with the nitrogen needs laws of high-quality tobacco. It also indicates that the combined application of organic additives and inorganic nitrogen fertilizer reduced the nicotine content of tobacco, increased the sugar/nicotine ratio and improved the quality of tobacco. The role of rice and rape straw is greater than the rapeseed cake, which can be used as measures to decrease nicotine content.

Key words: rapeseed fertilizer, rice straw, rape straw, nitrogen utilization rate, nitrogen contribution rate