Study On Soil Nutrients Condition And Rational Fertilization In Tobacco-growing Areas Of Chongqing Province

The characteristics of nutrients and conditions of abundance orabsence were studied,and comprehensive evaluation were conducted with respect tosoil planted with tobacco in Wulong county.The312samples were taked by GPSlocating and analysed with laboratory test.The results showed that most samples are ofmoderate content of organic matter, pH are of weak acidity,higher content of totalN,moderate content of available N,77.56%of samples are of P absence,approximately60%of soils are suitable for tobacco growing with moderate available K,available Cain about60%of soils are on the high side, and available Mg are in the range ofmoderate to abundance extent, available S in half of samples are absence.With regardto micronutrients,Moderate and higher content of available Zn account for62.50%and27.56%of total samples,that is to say the available Zn in most soils are suitablefor tobacco growing,77.24%of samples contain abundance available Cu,about90%ofsamples contain overabundance available Fe,Mn.The comprehensive value of INI indifferent nutrient grade at moderate,higher,high,lower,low is respectively39.10%,33.01%,7.05%,17.63%and3.21%.The research indicated that79.16%of totalsoils are suitable for tobacco planting.The study was carried out in order to determine the effects of different rate andratio for nitrogen（N）,phosphorus（P） and potassium（K） fertilization on yield andquantity of flue culed tobacco, and fertilizer effect function were fitted,D-optimaldesign was adopted in agricultural field experiment with15combinations of N,P andK. Evident difference exist between different treatments on total yield and percentageof fine grade tobacco of cured Leaves.The treatment N_4.5P₂K₂attained the highestyield of1640kg/ha and11.95%increased as compared with treatment N2P2K2,nevertheless, the ratio decrease with rate of nitrogen fertilizer increased. On the basisof recommendation fertilizing amount in local place,the yield were increased by7.62%,0.57%,9.78%at the rate of N,P and K were increased in treatment N₃P₂K₂, N₂P₃K₂and N₂P₂K₃respectively,and percentage of fine grade cured leaf decreasedcorrespondingly by16.05,13.15,13.57. In the all fertilizer combinations,the finegrade cured leaf was the least with10.09%in treatment N4.5P2K2with more nitrogenfertilizer than other and the highest with39.33%in treatment N2P2K2withrecommended fertilization. The yield and quality declined if rate of N,P and Kdecreased respectively. Tobacco yield response to fertilizer were fitted better withequation in one unknown,the regression model of two and three factors possess theadvantage which can give the maximum recommended fertilizing amount andeconomic optimum amount at taking into account interaction between each nutritionfactor. The range of recommended fertilization amount are N144¹92kg/ha，P2O594¹81kg/ha，K2O142kg/ha.