The Effect Of Equilibrium Fertilization On The Yield And Quality Of Flue-cured Tobacco

Equilibrium fertilization is one of methods of fertilizering which depends on trophic situation of soil, the absorption of various nutrients in different crops and the supplement of necessary nutrients, in order to obtain the most highest yield and the best ecnomic efficiency. Using flue-cured tobacco {Nicotiana tabacum L.) as materials, this study investigates the effect of equilibrium fertilization on the yield and quality of flue-cured tobacco based on the soil and climatic resources of Anshun city. The results were as follows:1. We collected and analysed 308 soil samples from Anshun city. The results showed that organic matter was abundant, with the average value of 2.79%;Rapidly available potassium and rapidly available phosphorus were middle in their contents;Exchangeable calcium and magnesium were rich;Sulfur was abundant;In microelements, the contents of chiorine and boron were deficient, with the mean value of 4.896 mg/kg and 0.391 mg/kg respectively;Contents of zinc and Cu were middle;Fe, Mo and Mn were very abundant. The pH ranges 4.44-7.12. Cation exchageability was lower. The suggestion of fertilization was: (1) Use less or none fertilizers for the soil of high organic matter, and supplement the nutrients when it is deficient. (2) Control the sulfur level, and use KNO3 in stead of K2SO4 whenever possible, warding off the adverse effects of high sulfur on quality of tobacco leaf. (3) Supplement microelement fertilizers, adding 0.1% boron and 4% chiorine fertilizers in specialty compound fertilizers. (4) Apply lime to improve some strong acid soils and the recommending formulating was: pure nitrogen 6.5 kg/667m2, base fertilizers (N:P2O5:K2O)=9:8:20, and top dressing (N:K2O)=13:26.2. Analysis of climatic resource of Anshun city showed that annual mean temperature is 15.2℃;>10 ℃ effective accumulated temperature is 4170.3⁴922.6℃;Annual average duration of sunshine is 1161.6¹426.1 hr, Percentage of sunshine in harvesting stage is 38.7⁴0.0%;Annual mean precipitation is 1218.4¹392.8 mm;>20℃ continuous days are over 70 days;Annual mean non-frost durations are over 270 days. The clmatic condition satisfied the production of favourable tobacco, but it distributed unbalance. The suggestion of fertilization was: (1) Solving the dissolution of fertilizer at early stage;(2) Applying the nitrogen at the rate of 8 kg/667m2;If excess rainfall, fertilization should be done two times. If drought, irrigation was necessary;(3) Supplementing the microfertilizers through foliar spaying, in order to improve the efficiency of fertilizers.3. Study of nitrogen forms on the yield and quality of flue-cured tobacco indicated that: tobacco plant growth period was curtailed 6 days when 100% fertilizer of NO₃--N was used, while the tobacco plant growth peiod was delayed 7 days when 100% fertilizer of NH₄⁺-N was applied. Their agronomic characteristics, yield, yield value, chemical components and quality of flue-cured tobacco were lower than that of mixture application of NO₃--N+ NH4+-N. The best treatment was obtained from the mixture consisting of 50% NH4+-N and 50% NO3--N, followed by the mixyure of 25% or 75% NO3--N and 25% or75% NH4+-N. The worst was observed from 100% NH4+-N or 100% NO3--N.4. In order to determine the suitable application rates of nitrogen, the field experiments evaluating effects of nitrogen rates on the yield and quality of flue-cured tobacco were conducted in Anshun city. The results showed that nitrogen rates increased from 0⁹.5 kg/667m2, the growth period of tobacco, plant height , width of stem, weights of leaf, contents of nicotine and total nitrogen, and incidence rate ofdisease raised slowly. Their yield and yield value increased significantly in comparison with the control (0 kg/667m2). When rates of nitrogen exceeded 8 kg/667m2, the flavor and ratio of high and middle grades decreased slowly. Reward of fertilizer input cost reduced slowly. Therefore, the suitable application rate of pure nitrogen was 8 kg/667m2 in Anshun city.5. The field experiments were conducted to determine the effects of various fertilizers formulating on the yield and quality of flue-cured tobacco in Anshun areas. The results indicated that under nitrogen rate of 8 kg/667m2, when inorganic fertilizers ratio increased, the growth period of tobacco was curtailed with the difference of 14 days among five treatments. The yield and yield value were enhanced obviously, and the contents of nitotine, total nitrogen, potassium and incidence rate of disease increased slowly. Flaver of flue-cured tobacco was also decreased. Comprehensive evaluation of tobacco indices indicated that the treatment with the eaqul ratio of inorganic fertilizer and organic fertilizer of 50 %, containing microelement fertilizers of chlorine and boron was the best in ambient condition of Anshun city. Plant height, width of stem, areas of single plant leaves, yield, yield value, disease resistance, smoking quality, and appearance qulity were very well except for the lowest contents of potassium in middle leaves. The yield and yield value reached significance when compared to other treatments. The 100% inorganic fertilizer or 100% organic fertilizer was defective to yield and quality of flue-cured tobacco.6. The plot experiments and investigations on effects of chlorine fertilizers on the yield and quality of flue-cured tobacco were conducted in chlorine-deficiency areas of Anshun. The results indicated that distribution of contents of chlorine in tobacco plant in Anshun was different with other tobacco growing areas. It was in the following order: upper lerf > lower leaf > middle leaf. The tobacco leaf quality was the best in the treatment of 37.5 kg/hm2 chlorine fertilizer. There was positive correlation between the contents of chlorine in tobacco leaves and rates of chlorine fertilizers. Contents of nicotine and total nitrogen were increased but contents of potassium reduced with the increment of chlorine fertilizers used. When chlorine fertilizers exceeded 75 kg/hm2, the growth of tobacco plant was inhibited with the lower mean weights of single leaves. In addition, the balance water increased by 0.49¹.73% and the tobacco leaf quality also reduced.7. In comparison of tobacco leaf quality of equilibrium fertilization in Anshun with the ones from Zimbabwe and Brazil, the results showed that oil contents of lower leaves and middle leaves were less than that from Zimbabwe and Brazil. Ripeness and looseness of upper leaves were lower compared to the standard of international flue-cured tobacco in appearance quality;As for chemical components, there was no difference in lower leaves when compared to international flue-cured tobacco;Contents of total nitrogen in middle leaves were 3.12%, which was higher than that of international flue-cured tobacco;But contents of potassium were 1.17%, which was lower than that of international flue-cured tobacco. The contents of nicotine, total nitrogen and chlorine were higher than that of international flue-cured tobacco in upper leaves. In comparison of tobacco leaf quality produced by equilibrium fertilization with international flue-cured tobacco, there was only slight difference in physical characteristics. The tobacco leaf quality of Anshun was middle to top level by smoking characterization. The quality of flue-cured tobacco of Anshun had reached international flue-cured tobacco, which could be used as the substitution for importing, and thus reduced the costs significantly.