Geochemistry Characters Of Base Element In Tibet Soils

Based on the analytic data of soil samples gathered from 489 soil layers of 139 soil profiles under 16 soil types in Tibet, the soils is divided into Calcic Soils and Non-Calcic Soils.the changes of content and transplant-enrichment character in soil base element Ca, Mg, K and Na. the result is:(1) Calcic Soils base gross (>100gkg"') is much more than Non-Calcic Soils base gross(<80 gkg"1).Among Non-Calcic Soils base gross, the content of Valley-Meadow soils is-the most; the soils of Mountain-humid forest: Yellow-brown earths> Yellow earths = Brown earths and Leached-cinnamon soils > Dark-brown earths> Podzolic soils; Alpine soils: Dark felty soils> Felty soils and Frigid frozen soils (which parent material is calcareous is excluded). However, among Calcic Soils base gross, Alpine hungriness soils is the mostthe second is Meadow soils which is the soils of Valley semihydromorphic soils and Fluvo-aquic soils.the last is the soils of mountain (Arid valley), forest shrub type and Alpine steppe type.(2) According to the compose of base element(percentage against gross),the total trend of base compose in Non-Calcic Soils is :K2Oa2O>MgO>CaO,that is to say,the content of alkali metals base is more than alkaline earth base,moreover, K2O is the most, CaO is the least. The total trend of base compose in Calcic Soils is: CaO2O>MgO>Na2O,that is to say, CaO is the most,but K2O is still the second,only the content of MgO in Cold frozen soils is a little more than the one of K2O, the content of Na2O in Cold calcic soils and Fluvo-aquic soils is a little more than MgO.(3) Transplant-enrichment degree is reflected by interbedded variabl coefficient of base content in soils profile.As far as soil type are concerned, the transplant-enrichment of base in Calcic Soils is more abvious than Non-Calcic Soils,however, different soils type is variational. For base element, whether Calcic Soils or Non-Calcic Soils, the interbedded variabl coefficient of CaO is the most,then in turn MgO>Na20~K2O, it is indicated that Ca is the most active in transplant-enrichment of base element in Tibet soils, moreover, it is representational significance in transplant-enrichment of total base, therefore,it is summed up "calcic accumulation pross".(4) On wide altiplano in Tibet, the horizontal belt variety of base tone in soils is obvious.The distributed area of Alpine steppe soils (Non-Calcic Soils ) in Tibet southeast is the one which base content is little in soils. K2O is the most in base matter, the interbedded variety of calcium and magnesium is relative little in soilsprofile. Alpine steppe soils(Calcic Soils)which is distributed from Tibet southeast to central section and northwestward is high cost ozone of soils base, CaO is primary in base matter, but KO is the second; the interbedded variety of Calcium and Magnesium is relative great in soils profile, especially Alpine desert soils in Tibet northwestward, base gross is the most, but interbedded variety in soils profile is decreased by a long way. Base status in Tibet soils is also vertically zone variety by all means, but represent is more complicated.(5) According to base gross and profile accumulation index of CaO in soils, the character of calcic accumulate in soils is divided into surface-accumulate type(PAl> 1.0) and bottom-accumulate type(PAI< 1.0). Surface-accumulate type is divided into base transplant outsurface accumulate type(Non-Calcic automerphous soils) and base transplant intosurface-accumulate type(valley semihydromorphic soils), the latter is divided into Calcic and Non-Calcic. Calcic automerphous soils often is base or calcic bottom-accumulate type. But Alpine desert soils is the character of surface-accumulation or subsurface-accumulation.(6) The mechanism of calcic accumulate in soils is divided into biologic calcic accumulate mechanism and chemic calcic accumulate one. biologic calcic accumulation is arosed by biologic organic accumulation, moreover.)! is the character of surface-accumulation, Non-Ca...