Soil OM was one of major indexs to assess ability of soil N supply. The experiment was carried out to study the effect of soil OM on characteristics of soil N release, DM and N accumulation of fule-cured tobacco and nicotine accumulation of tobacco leaves after topping and the quality of tobacco leaves by using field training in site, N-free zone biomass absorption method and 15N isotope tracer technique in red soils of three different level of OM content. The main results obtained were as following:...