Effects Of Fertilization On The Growth Of Flue-cured Tobacco And Peanut And Rhizospheric Nutrients

Both tobacco and peanut are main commercial crops in China and play an important role in the sustainable development of national economy. Fertilization is one of the most important agricultural strategies to regulate crop development and growth whereby to improve crop yield and quality. There are active exchanges of nutrients between root and soil in the rhizosphere of crops, being considered a crucial interface among soil, root and microbe.There are many differences between rhizosphere and nonrhizosphere soil. Root respiration, secretion, and absorption of nutrients and water influence directly and indirectly the physical and chemical properties of rhizosphere soil. Research on nutrients in rhizosphere is beneficial to realize the essence of soil fertility and nutrient supplies for plants by which to promote plant nutrient absorption, mobilize insoluble nutrients, increase fertilizer use efficiencies and fertilizer crops scientifically. In our present experiment, root container culture technique was used to study the influence of fertilization on the growth of tobacco and peanut and rhizospheric nutrients. Experiment treatments included blank control (without fertilizer), chemical fertilizer, organic fertilizer (swine manure) and mixture of chemical and organic fertilizer. Folowing are main results:1. Combined application of organic and inorginac fertilizer increased the biomass of tobacco seedling by1.2times, nutrient absorption by1.4times at least.2. Soil pH in near the roots (0-3mm) is significantly lower than that far from the roots (over5mm). Chemical fertilization significantly decreased soil pH in the rhizosphere of tobacco in contrast combined application of organic and inorganic fertilizers which had no significant influence on pH in the same soil. Therefore, fertilizing soils with chemical fertilizer only could cause acidification, but combined application of organic and inorganic fertilization could avoid this negative effect.3. Ammonium nitrogen moved slowly in soil compared to absorption by tobacco seedlings. Fertilization significantly enhanced the ammonium nitrogen and available nitrogen in the rhizosphere of tobacco, indicating the increment of the intensity of soil nitrogen supplies. Nitrate moved easily toward to plant roots in the rhizosphere and adding chemical fertilizer into soils increased the content in the rhizosphere soil. Organic fertilization increased significantly organic matter in the same soil.4. Available phosphorous and potassium in the soil near the tobacco seedlings were lower than the soils far from roots, suggesting the faster absorption of the two nutrients by tobacco seedlings than soil supplies and the regulation of rhizospheric nutrients by rational fertilization. Combined application of organic and inorganic fertilization raised available phosphorous in the rhizosphere but decreased both Al-P and Fe-P in the soil near the roots, indicating that the treatment promoted the utilization of Al-P and Fe-P by the seedlings. In contrast, both Ca-P and O-P changed little, if any, being a potential P source.5. Organic fertilization increased significantly enzyme activities in the rhizosphere soil. Higher activities near the roots were observed than the nonrhizosphere.6. The highest biomass and nutrient uptake by peanut was obtained by organic fertilization. The biomass of peanut seedlings were increased by28.27%(organic fertilizer),12.66%(chemical fertilizer) and7.17%(combined fertilization) on the base of blank control, showing the growth improvement by fertilization. The Highest K uptake by peanut seedlings was detected in organic fertilizer treatment (increased by35.82%over blank control) and followed by combination fertilization, which increased by20.1%compared with the control.7. pH in root zone soil of peanuts was significantly lower than far root zone soil. pH Higher pH in the rhizosphere was found in Organic fertilizer treatment than any other treatments.8. Fertilizer increased the ammonium nitrogen and available nitrogen in rhizospheric soils of peanut significantly.No significant deficit of available nitrogen and ammonium nitrogen was observed in rhizopheric soils while nitrate nitrogen accumulated on root surface.Applying of fertilizer significantly enhanced nitrate nitrogen in rhizopheric soils.Organic fertilizer increased organic in rhizopheric soils significantly. 9. K in soil near peanut roots was lower than that far from the roots. Organic fertilizer and mixture of organic and chemical fertilizers increased significantly available K in rhizospheric soils, indicating the improvement of K for the peanut seedlings. As a result, K concentrations increased obviously in peanut seedlings.10. Available phosphorus, Al-P, Fe-P and organic phosphorus in rhizopheric soils of fertilizer treatments of peanut were higher than that of blank control, indicating that fertilizer enhanced phosphorus intensity and capacity in rhizopheric soils, Combined application of organic and inorginac fertilizer enhanced the using ability of Al-P, Fe-P and organic phosphorus by tobacco seedlings but decreased Al-P and Fe-P near the root.11. Higher enzyme activities near the roots were observed than the nonrhizosphere of peanut.Organic fertilizer increased the activity of urease, invertase and acid phosphatase in rhizopheric soils of peanut while applying inorganic fertilizer only decreased the activity of enzyme.12.Combined application of organic and inorginac fertilizer coordinated supply-demand of nutrients in rhizopheric soils of peanut and tobacco, promoted the growth and development of plant. Organic fertilizer significantly promoted growth of peanut and efficient utilization of nutrients in the rhizophere soil which indicated that fertilizer environment was beneficial to growth of root nodule and interaction effects.