Comparative Study On Soil-Forming Process Between Different Aroma Type Of Flue Cured Tobacco

The soil is the site conditions for crop growth, the soli-forming process influence the various properties of the soil characteristics. Currently, the literature about the effect of soil property on aroma type differentiation of flue cured tobacco was more, while the effect of soil forming process on differentiation of aroma type of flue cured tobacco was rarely reported. In order to explore relationship between soli-forming process and differentiation of aroma type of flue cured tobacco,40soil profiles located in eighteen counties of three provinces (Fujian,Yunnan,Sichuan) of clean aroma type tobacco region(CATTR) and26soil profiles located in ten counties of four provinces (Henan,Shanxi,Guangdong,Jiangxi) of full aroma type tobacco region(FATTR) were observed, and283soil horizon samples were collected and tested, various soil-forming process were analyzed. The main conclutions are follows:(1) The humus accumulation process was universal in CATTR and FATTR, and the humus content drops with soil depth increasing. Soil humus and its composition content were significantly different between the two aroma type tobacco regions, The soil humus activation degree in CATTR were higher than those in FATTR.(2) There was clay eluviation deposition process in both CATTR and FATTR. The soil sand and clay content in CATTR were significantly higher than those in FATTR, while the soil silt content was inversely.The ratio of silt/clay in CATTR were significantly higher than those in FATTR., meaning a more profound weathering.(3)The soil calcification process was obvious different between CATTR and FATTR. The value of calcium carbonate in CATTR range from5.0-29.7g/kg with an average of11.6g/kg and the decreased with soil depth increasing, in CATTR it was mainly artificially recalcification caused by cultivation. The value of calcium carbonate in CATTR range from8.0-53.lg/kg with an average of32.36g/kg, In FATTR it was the calcium carbonate eluviations from topsoil and illuviation in subsoil.(4) Desilicification and Allitization process was obvious different between CATTR and FATTR. For most of the allitic soil in CATTR, the ratio of SiO2/Al2O3were no more than2.2, the ratio of Al2O3/Fe2O3fluctuated slightly around2.0, while those values for allitic soils in FATTR were above3.5and fluctuated slightly around2.5. The value of free ferrum of the allitic soil in CATTR was50.89g/kg in average and activation degree of ferrum was23.3%in average, while those values for allitic soils in FATTR were27.69g/kg and22.4%. Most of soil in CATTR were in the phase of allitization, while most of soil in FATTR were in the phase of ferritization.(5) Oxidation and Reduction processes in soil was unconspicuous different between CATTR and FATTR. There were abundant rust streak and rusty spot with various size. Ferrum and Manganese nodule existed in plow sole downward. Ferrum oxide and Manganese oxide content in soil was unconspicuous different between CATTR and FATTR. Different aroma type tobacco region free ferrum oxide (Fed) and free manganese oxide (Mnd) content all had a tendency to increased with soil depth increasing, the same as (Fed-Feo) and (Fed-Feo)/Feo. The content of amorphous ferrum oxide(Feo) and Feo/Fed all had a tendency to drop with soil depth increasing in differentiation of aroma type of flue cured tobacco. The same as amorphous manganese oxide Mno and (Mnd-Mno) content in clean aroma type tobacco region. But the content of Mno and (Mnd-Mno) increased with soil depth increasing.(6) The soil CIA index and the weathered eluvial coefficient (ba) in CATTR was significantly higher than those in FATTR. The soil weathering eluvial index(P) and weathering grade(μ) was unconspicuous different between CATTR and FATTR.