Nitrogen Accumulation,Distribution and Utilization Low of Flue-cured Tobacco on Soil with Different Organic Matter Content at Various Nitrogen Application Levels

To explore the relationship of nitrogen accumulation in flue-cured tobacco with organic matter content in soil and nitrogen application levels,a field experiment was conducted to explore the nitrogen accumulation,distribution and utilization low on yellow soil with different organic matter content.Results: 1) Without nitrogen applied,the nitrogen accumulation amount grew continuously in growth stage and kept increasing with the increase of organic matter in soil;Under the same nitrogen level,nitrogen accumulation of tobacco plants on soil with high organic matter content occurred mainly within 77 d after transplanting.While occurred in the whole growth stage on soil with low organic content.Meanwhile,the total nitrogen accumulation showed no significant change under high nitrogen levels.2) Under the same nitrogen levels,the fertilizer N and soil N of tobacco plants with high organic matter content in soil were mainly absorbed during 77 d after transplanting.While with low organic matter content in soil,a large quantity of fertilizer N and soil N accumulation continued in 77~119 d.3) The total fertilizer N accumulation made up 33.59%~48.26% of the total nitrogen accumulation;the total soil N accumulation made up 51.74%~66.41% of the total nitrogen accumulation.The soil N was the main source of nitrogen nutrition for tobacco plant and it decreased with the increase of nitrogen levels and organic matter in soil.It was also the source of nitrogen nutrition for leaf blade in different part the tobacco plant and its nitrogen accumulation increased with the ascending of the leaf blade.4) The utilization of nitrogen fertilizer for tobacco plant was mainly centered on the vigorous growing stage(36~77 d).Under the same nitrogen level,the nitrogen accumulation increased with the increase of organic matter content in soil.Under the optimum nitrogen condition,planting the tobacco in high organic soil was helpful to its early growth and the nitrogen accumulation.It was also beneficial to the development of the plant and the forming of the dominant plant as early as possible.The result was not good through increasing the nitrogen levels to increasing the nitrogen accumulation of the tobacco plant.Therefore,nitrogen level should be subject to local optimum dosage.At the same time,to increase the utilization ratio of nitrogen fertilizer and save nitrogen fertilizer input cost,soil with high organic matter content could be chosen to plant the flue-cured tobacco.