Comparative Study Of Rare Earth Elements Content And Main Chemical Indexes Of Soil Between Clean Aroma Type Tobacco Region And Full Aroma Type Tobacco Region

The geological background of crop growth,especially mineral elements contents and occurrencedirected affect the growth of crop and yield and quality of agricultural products. While，the effect of rareearth elements in soil on quality of aroma type of flue cured tobacco was rarely reported.In order toclarify the correlation between rare earth elements,main chemical indexes of soil and flue cured tobaccoaroma,50soil samples were selected from eleven counties of three provinces (Yunnan,Sichuan,Fujian)of clean aroma type tobacco region and51soil samples from ten counties of five provinces(Hunan,Henan,Guangdong,Jiangxi,Anhui) of full aroma type tobacco region. With methods of fieldsurvey,lab analysis and regional correlation,this paper deals with the main chemical indexes of soil andthe contents and distribution characteristics of16types of rare earth elements (REEs) in soils of cleanaroma type tobacco region and full aroma type tobacco region.The main conclusions were as follows:(1) The value of ΣREEs of the soil in clean aroma type tobacco region and full aroma type tobaccoregion are higher than those of whole country. Probability distribution functions of rare earth elementscontents in soils of two aroma type tobacco regions is similar,but the variation of clean aroma typetobacco region is more than that of full aroma type tobacco region.The value of ΣREEs in clean aromatype tobacco region range from158.36～523.25mg/kg with an average of273.87mg/kg,belonging tomoderate variability, and the content of Ce conformed to logarithmic normal distribution, other elementsconformed to normal distribution. The value of ΣREEs of the soil in full aroma type tobacco regionrange from166.04～345.93mg/kg with an average of242.20mg/kg,belonging to weak variability andall of the rare earth elements conformed to normal distribution.（2）The order of rare earth elements contents in clean aroma type tobacco region is consistentwith that in full aroma type tobacco region except for Nd and Y. The rare earth elements contents ofclean aroma type tobacco region in order: Ce＞La＞Nd＞Y＞Sc＞Pr＞Sm＞Gd＞Dy＞Er＞Yb＞Eu＞Ho＞Tb＞Lu＞Tm; the rare earth elements contents of full aroma type tobacco region in order: Ce＞La＞Y＞Nd＞Sc＞Pr＞Sm＞Gd＞Dy＞Er＞Yb＞Eu＞Ho＞Tb＞Lu＞Tm.（3）Sixteen types of rare earth elements in soils of flue cured tobacco region can be classified intothree principal component，the contribution rate of three principal component was up to73.50%,9.24%and8.51%,cumulative contribution rate was up to91.25%.(4) Rare earth elements contents in soil and the spatial differentiation of aroma type of tobaccohad close correlation. The value of ΣREEs and Sc,Gd,Dy of soil in clean aroma type tobacco region wassignificantly higher than those in full aroma type tobacco region. The value of ΣHREEs and La, Pr, Nd,Sm, Eu, Tb of soil in clean aroma type tobacco region was very significantly higher than those in fullaroma type tobacco region. There was a significant difference in the value of principal component Z1and a very significant difference in the value of principal component Z2,Z3between clean aroma typetobacco region and full aroma type tobacco region.(5)The distribution pattern of REE in soil of two aroma type tobacco regions exhibitLREE-enrichment,but the degree of enrichment of LREE in clean aroma type tobacco region wasgreater than that in full aroma type tobacco region. Clean aroma type tobacco region present negative Eu anomaly and Ce normaly, full aroma type tobacco region present negative Eu anomaly and weakpositive Ce anormaly. The degreeof loss of Eu of full aroma type tobacco region was greater than cleanaroma type tobacco region.(6)The variation of rare earth elements contents between soil types of two aroma type tobaccoregion are different.The rare earth elements contents of main soil types(paddy soil,red earth,purple soil)of clean aroma type tobacco region showed no significant difference, the rare earth elements contents inpaddy soil of full aroma type tobacco region was significantly higher than those in moisture soil andcinnamon soil.(7) REE level was affected mainly by the parent materials. The highest value of REE of cleanaroma type tobacco region was hydromorphic paddy soil derived from granite and the lowest wascalcareous purple soil derived from purple sandstone. The highest value of REE of full aroma typetobacco region was hydromorphic paddy soil derived from limestone and the lowest was hydromorphicpaddy soil derived from river alluvium.(8)Soil pH is very likely to influence the spatial differentiation of aroma type of tobacco. The valueof soil pH in full aroma type tobacco region was significantly higher than those in clean aroma typetobacco region.The soil organic matter content of two aroma type tobacco regions had significantpositive with soil total N content.