Study On Field Nutrient Release And Absorption Law Of Special Organic-Inorganic Compound Fertilizer Of Flue-cured Tobacco

The study was carried out through field experiment to investigate the effects of different kinds of fertilizers, different application rates of organic-inorganic composite fertilizer and different application methoths on growth and development of flue-cured tobacco plants of several main varieties in China, and the field nutrient release and nutrient absorption pattern of tobacco plant. The results were as fellows:1 . From growth and development of tobacco plant, activities of rhizosphere soil microorganisms of tobacco plant had been effectively inflected by application of organic-inorganic compound fertilizer. Quantity of rhizosphere soil microorganisms of tobacco plant applied with organic-inorganic compound fertilizer in rosette stage had been obviously increased, which was good for decomposing organic substances, improving effectiveness of nutrient and promoting fast growth of tobacco plant. While, the quantity of rhizosphere soil microorganisms of tobacco plant in rosette stage was obviously low in topping stage, which was good for reducing mineralization of organic nitrogen of tobacco field soil in later stage, decreasing nitrogen absorption of tobacco plant in later stage and promoting natural maturity of tobacco plant. The quantity of rhizosphere soil microorganisms of tobacco plant applied with chemical fertilizer was markedly high in topping stage to result in maturity retarding of tobacco plant because of high quantity of mineralized nitrogen of rhizosphere soil of tobacco plant in later stage.2. Application of organic-inorganic compound fertilizer could promote natural growth of tobacco plant in early stage, accumulation of photosynthesis outcome of tobacco plant in middle stage and timely maturity of tobacco plant in later stage. Though combined application of oil cake and chemical fertilizer and single application of chemical fertilizer was favorable to growth of tobacco plant in early stage, dry substance was accumulated relatively less in middle stage and relatively excessive in later stage.3. The results of ¹⁵N isotopic tracer show that different application methods directly affect mineralization of organic nitrogen of field soil after topping of tobacco plant and nitrogen accumulation in tobacco plant. Compared with single application of chemical fertilizer, application of organic-inorganic compound fertilizer had promoted obviously mineralization of organic nitrogen in tobacco field soil from vigorous growing stage to topping stage of tobacco plant and obviously reduced quantity of mineralization of organic nitrogen in the soil after topping. While, single application of chemical fertilizer represents later-stage nitrogen supply in the mature stage of tobacco plant. At end of tobacco leaf gathering, the proportion of nitrogen accumulated from fertilizer nitrogen in tobacco plant applied with organic-inorganic compound fertilizer was 32%, while the proportion of fertilizer nitrogen in total absorbed nitrogen content of tobacco plant applied with chemical fertilizer was 27%. In terms of nitrogen utilization efficiency, the result of ¹⁵N isotopic tracer showed that utilization efficiency of inorganic nitrogen could be improved through application of organic-inorganic compound fertilizer rather than application of chemical fertilizer.4. The level of nitrogen fertilizer application and fertilizer varieties had affected inorganic nitrogen supply for soil in dense root area during the period of tobacco plant growth and further the growth of tobacco plant. According to the test, higher application level of nitrogen fertilizer results in more inorganic nitrogen supply for soil in dense root area. From the growth of tobacco plant and within a certain range of nitrogen application rate, accumulation of dry substance at the root and in the body of tobacco plant is increased with the increase of nitrogen application rate. However, accumulation of dry substance at the root and in the body of tobacco plant would be limited by excessive nitrogen application rate. Meanwhile, too high level of nitrogen fertilizer application will cause accumulation of more nitrogen in the tobacco plant in later stage of its growth and thicker leaves in the upper and middle part of the plant. It was unfavorable toimproving quality of tobacco. Compared application of organic-inorganic compound fertilizer with application of chemical fertilizer, the level of inorganic nitrogen supply in soil, such as ammonium nitrogen and nitrate nitrogen, was appropriate in the whole growth period. The fertilizer supply was sufficient but not excessive in early stage, and balanced but not high in later stage. It was better for fast growth in the early stage and timely maturity in the later stage of the tobacco plant.5. There were no obvious differences between accumulation of nutrients as nitrogen, phosphorus and potassium in tobacco plant with different nitrogen application rate before topping, while the accumulation of these nutrients was increased with increase of fertilizer application rate after topping. From the nitrogen accumulation in tobacco plant, quantity of accumulated nitrogen in tobacco plant had little increase after topping, compared to the quantity at topping when in appropriate nitrogen application rate or below. However, the quantity of accumulated nitrogen was quite much while the nitrogen application rate was too high.