The Evaluation Of Soil Fertility And The Relationship Between Soil Nutrients Contents And Chemical Components In Flue-Cured Tobacco Leaves In Hunan Tobacco-Growing Areas

A serial field survey,and laboratory analysis were conducted by this investigation to test the content of chemical components in 308 flue-cured tobacco leaves samples and nutrients content in 1342 soil samples in Hunan tobacco-growing areas.The grading of soil nutrients was plotted in Hunan tobacco-growing areas,the comprehensive evaluation of soil fertility of Liuyang tobacco-growing areas was conducted for all the samples. Relationship models of chemical components in flue-cured tobacco leaves and soil organic matter contents were founded,and the effect of soil organic matter contents to chemical components in flue-cured tobacco leaves were analyzed;the relationship of P content in flue-cured tobacco leaves to available P in soil,S content in flue-cured tobacco leaves to available S in soil,B content in flue-cured tobacco leaves to available B in soil,Mn content in flue-cured tobacco leaves to available Mn in soil,Zn content in flue-cured tobacco leaves to available Zn in soil were analyzed.The main results were as follows:1.The content of soil pH 6.38 was suitable in Hunan tobacco-growing areas,the content of soil organic matter was rich,with the mean of 35.66 g·kg^-1;the content of soil pH,total N, hydrolysis N,available P and total K were suitable,with the mean of 6.38,2.10 g·kg^-1,177.35 mg·kg^-1,19.67 g·kg^-1and 14.92 g·kg^-1;the content of soil total P,available K and available B were low,with the mean of 0.78 g·kg^-1,140.28 mg·kg^-1and 0.23 mg·kg^-1;the content of soil exchangeable Ca,exchangeable Mg and soluble Cl were also suitable,with the mean of 9.50 cmol·kg^-1,1.30cmol·kg^-1and 14.01 mg·kg^-1;the content of soil available Cu and available Fe were very high,with the mean of 3.31 mg·kg^-1and 80.88 mg·kg^-1;the content of soil available S, available Zn,available Mn and available Mo were all rich,with the mean of 37.16 mg·kg^-1,2.27 mg·kg^-1,27.83 mg·kg^-1and 0.18 mg·kg^-1,respectively.2.Take Liuyang tobacco-growing areas for an example,based on methods of multivariate statistical analysis and principles of fuzzy mathematics,the comprehensive evaluation of soil fertility of 245 soil samples was conducted.The results indicated that there existed significant variation for the soil fertility of Liuyang tobacco-growing areas.The areas of gradeâ… and gradeâ…£are both small,and accounted for 0.65%and 1.67%of the total Liuyang tobacco-growing areas,respectively;the areas of gradeâ…¡and gradeâ…¢are both large,and accounted for 48.23% and 49.45%of the total areas,respectively.Comparison among five main soil types whose areas accounted for 70.88%of total Liuyang tobacco-growing areas showed that the integrated fertility index(IFI)was in the order of red yellow mud＞blue mud field＞yellow mud field＞sand mud field＞yellow sand mud.3.Based on 222 tobacco and soil samples from Hunan tobacco-growing areas, relationship between chemical components in flue-cured tobacco leaves and soil organic matter content was analyzed.The results indicated that:(1)There existed different variation for chemical components in flue-cured tobacco leaves.Contents of total N and potassium were high;contents of nicotine,total sugar,chlorine and reducing sugar were suitable.(2) Relationshlp between nicotine content in flue-cured tobacco leaves and organic matter content in soil could be described by linear-flat model,with the turning point being 36.25 g·kg^-1for content of soil organic matter,and content of nicotine being 3.00%at this flat stage.The higher the soil organic matter was,the higher the nitrate and nitrite were,and the correlation coefficients of them were both high significant.The content of petroleum ether extract,however,seemed to show decreasing trend with increasing of soil organic matter content.(3)After grouping soil organic matter contents and by using multiple comparison method,significant differences at 0.05 level among groups were found for chemical components in flue-cured tobacco leaves including nicotine,total N,nitrate,nitrite, petroleum ether extract,potassium,chlorine,proportion of nitrogen to nicotine,proportion of reducing sugar to nicotine,and proportion of potassium to chlorine.However,differences among groups for contents of total sugar and reducing sugar were not significant.4.Distribution of phosphorus content in 308 flue-cured tobacco leaves samples and available phosphorus content in 1342 soil samples,and relationship between phosphorus content in flue-cured tobacco leaves and soil available phosphorus in Hunan tobacco-growing areas were studied.The results indicated that:(1)The phosphorus content in flue-cured tobacco leaves was suitable in total in Hunan tobacco-growing areas,which ranged from 0.11%to 0.53%,with the mean of 0.24±0.07%;the order of the phosphorus content in flue-cured tobacco leaves among different grades was B₂F＞C₃F＞X₂F.(2)Total phosphorus content in soil was low in Hunan tobacco-growing areas,which ranged from 0.18 g·kg^-1to 3.83 g·kg^-1,with the mean of 0.78±0.31 g·kg^-1,and about 78.32%samples of total were lack of phosphorus(≤1.00g·kg^-1);Available phosphorus content in soil was medium in Hunan tobacco-growing areas,which ranged from 1.00 mg·kg^-1to 92.10 mg·kg^-1 with the mean of 19.67±13.63 mg·kg^-1and about 29.66%samples of total were lack of phosphorus(≤10.00 mg·kg^-1);The order of available phosphorus content in soil for different types was duck feces mud＞yellow mud field＞blue mud field＞sand mud field＞red yellow mud＞yellow soil＞yellow ash soil.(3)The phosphorus content in flue-cured tobacco leaves had high significant positive correlation at the 0.01 level with available phosphorus content in soil with correlation coefficient of 0.260,and also had high significant positive correlation at the 0.01 level with soil organic matter,total N,hydrolysis N,available Cu,available Fe,available S and soluble Cl in soil,but had negative correlation at the 0.05 level with soil total K,available Mn,available Mo and exchange Mg in soil. Based on the correlation analysis,multiple stepwise regression equations were built between soil nutrients and the phosphorus content in flue-cured tobacco leaves.(4)After grouping soil available phosphorus content and with the increasing of soil available zinc content,the zinc content of different grades in flue-cured tobacco leaves showed the trend of increasing firstly and decreasing later.Significant differences at the 0.01 level among groups were found for the phosphorus content in flue-cured tobacco leaves after grouping soil available phosphorus content;with the increasing of soil available phosphorus content,the phosphorus content in flue-cured tobacco leaves show the increased,when the content of soil available phosphorus was low.5.Distribution of sulfur content in 308 flue-cured tobacco leaves samples and available sulfur content in 1342 soil samples,and relationship between sulfur content in flue-cured tobacco leaves and soil available sulfur in Hunan tobacco-growing areas were studied.The results indicated that:(1)The sulfur content in flue-cured tobacco leaves was relative high in all Hunan tobacco-growing areas as compared with other areas in China,which ranged from 0.34%to 1.49%with the mean of 0.81%±0.26%;only about 39.29%tobacco samples were with in the range of 0.20%～0.70%;the order of the sulfur content in flue-cured tobacco leaves among different grades was B₂F＞C₃F＞X₂F.(2)Available sulfur content in soil was rich in Hunan tobacco-growing areas,which ranged from 2.20 to 217.60 mg·kg^-1 with the mean of 37.16±27.59 mg·kg^-1.The order of available sulfur content in soils of different types was duck feces mud＞yellow mud field＞red yellow mud＞blue mud field＞sand mud field＞yellow ash soil＞yellow soil.(3)The very significant positive correlation ship between contents of sulfur in flue-cured tobacco leaves and soil available sulfur was revealed at the level 0.01(r=0.469),and the regression equations for different grades were also established.(4)The field experiment of effects of sulfur rate on the sulfur content of flue-cured tobacco leaves showed the same trend of relationship what we found in field survey,and the residual soil available sulfur content also increased with the increasing of sulfur rate used after harvesting the flue-cured tobacco leaves. 6.Based on 288 tobacco and soil samples from Hunan tobacco-growing areas, relationship between the boron content in flue-cured tobacco leaves and the soil available boron content in Hunan tobacco-growing areas was analyzed.The results indicated that:(1) The boron content in flue-cured tobacco leaves in Hunan Province was low,which ranged from 9.22 to 89.04 mg·kg^-1with the mean of 21.72±12.98 mg·kg^-1.The boron content of 88.89%tobacco samples located at the range of 10.00～40.00 mg·kg^-1.(2)The soil available boron content in Hunan tobacco-growing areas was low,which ranged greatly from 0.07 to 1.28 mg·kg^-1with the mean of 0.25±0.23 mg·kg^-1.(3)The boron content in flue-cured tcbacco leaves had high positive correlation(r=0.745)with the soil available boron content at 0.01 level.Based on the correlation analysis,the regression equation,(?)=11.47+41.71x, was built between soil available boron and the boron content in flue-cured tobacco leaves for 288 samples.(4)After grouping soil available boron contents and by using ANOVA method,high significant differences at the 0.01 level among groups were found for the nicotine content,proportion of nitrogen to nicotine,and proportion of total sugar to nicotine. However,differences among groups for contents of total N and total sugar were not significant.7.Distribution of manganese content in 257 flue-cured tobacco leaves samples and available manganese content in 1342 soil samples,and relationship between manganese content in flue-cured tobacco leaves and soil available manganese in Hunan tobacco-growing areas were studied.The results indicated that:(1)The manganese content in flue-cured tobacco leaves was high in total in Hunan tobacco-growing areas,which ranged from 15.00 to 740.80 mg·kg^-1with the mean of 146.66±134.03 mg·kg^-1;the order of the manganese content in flue-cured tobacco leaves among different grades was X₂F＞B₂F＞C₃F.(2)Available manganese content in soil was much high in Hunan tobacco-growing areas,which ranged from 1.30 to 174.30 mg.kg^-1with the mean of 27.83±22.39 mg·kg^-1.The order of available manganese content in soil for different types was yellow soil＞yellow ash soil＞yellow mud field＞red yellow mud＞duck feces mud＞sand mud field＞blue mud field.(3)The manganese content in flue-cured tobacco leaves had high significant positive correlation at the 0.01 level with available manganese content in soil with correlation coefficient of 0.481.Based on the correlation analysis,the regression equation,(?)=58.45+3.80x,was built between soil available manganese and flue-cured tobacco leaves manganese content in 257 samples.(4)After grouping soil available manganese content and with the increasing of soil available manganese content,the manganese content of different grades in flue-cured tobacco leaves increased,and significant differences at the 0.01 level among groups were found for the manganese content of different grades in flue-cured tobacco leaves.The experiment about adding manganese in soil showed the same trend.After harvesting flue-cured tobacco leaves and with the increasing of manganese used,the residual of soil available manganese also increased.8.Based on 256 tobacco and soil samples from Hunan tobacco-growing areas,relationship between the zinc content in flue-cured tobacco leaves and available zinc content in soil and their relationship in Hunan tobacco-growing areas were studied.The results indicated that:(1)The zinc content in flue-cured tobacco leaves was suitable in total in Hunan tobacco-growing areas, which ranged from 10.50 to 100.50 mg·kg^-1with the mean of 36.30±14.05 mg·kg^-1;the order of the zinc content in flue-cured tobacco leaves among different grades was B₂F＞C₃F＞X₂F.(2) Available zinc content in soil was medium in Hunan tobacco-growing areas,which ranged from 0.13 to 62.59 mg·kg^-1,with the mean of 2.27±3.74 mg·kg^-1and variation coefficient of 155.09%. The order of available zinc content in soil for different types was duck feces mud＞yellow mud fied＞yellow ash soil＞yellow soil.(3)The zinc content in flue-cured tobacco leaves had high significant positive correlation at the 0.01 level with available zinc content in soil with correlation coefficient of 0.312,and also had significant positive correlation at the 0.05 level with available Cu,available Fe and available S in soil,but had negative correlation at the 0.05 level with pH value,available K and water soluble Cl in soil.(4)After grouping soil available zinc content and with the increasing of soil available zinc content,the zinc content of different grades in flue-cured tobacco leaves showed the trend of increasing firstly and decreasing later. Significant differences at the 0.05 level among groups were found for the zinc content of different grades in flue-cured tobacco leaves.