Nitrogen Absorption and Utilization of Flue-Cured Tobacco in Liuyang

¹⁵N-labelled experiments were designed to study the effect of different nitrogen amount on dry matter accumulation and nitrogen uptake, residue and loss of flue-cured tobacco in Liuyang. The results showed that the nitrogen accumulation ratio of leaf, stem and root was 1:2.5:6.5. 58.14%-62.55% of N absorbed by flue-cured tobacco was derived from fertilizer under different N levels, while 37.45%-41.86% of the absorbed N was from the soil. Fertilizer N utilization efficiency (NUE) of base and topdressing fertilizer N was from 28.25% to 40.18% and from 35.95% to 69.62% respectively. NUE of base fertilizer N was increased with the increase of topdressing N, NUE of topdressing N was decreased with the increase of topdressing N. Under the 158 kg/ha N level, with the increase of N fertilizer, NUE and soil residual rate increased, from 21.97% to 23.55% and from 35.97% to 39.47%, but the increase was not significant. Fertilizer N loss rate decreased, from 36.98% to 42.07% under this condition. AT the 158 kg/ha N level, tobacco dry matter, total N accumulation, fertilizer N accumulation were the highest (5321.05, 97.17 and 60.78 kg/ha), and the fertilizer N loss rate was the lowest (36.98%).