| Nowdays, the international majority of soil classification is the Soil Taxonomy, which is based on the Diagnostic horizon and Diagnostic characteristics, and characterized by quantification.The tendency of soil classification in the world is quantification, standardization and intemationalization.The study of Chinese Soil Taxonomy has achieved great phase outcome-Chinese Soil Taxonomy. It is necessary to put classification system into scientific research, practice and make it consummate.Qinling Mountain is the important boundary of physical geography and environment between the south and north part of China.The natural landscape varys regularly and gradually in verticality. The various mountain climate, biology, landform and parent materiall lead to numerous soil types and different distribution of soils in verticality. Fourteen typical profiles of different altitude on the south slope of the Taibai Peak of Qinling Mountaint, which is 3767 meters in altitude, were researched in this study.By field survey, the physical and chemical characteristics anasysis of the soils, we studied thoroughly the soil Genetic, discussed the positions in Taxonomic classification and the distribution of the soils on the basis of the Keys to Chinese Soil Taxonomy (3rd edition), and to provide the foundation of Soil Taxonomy of mountain and resources development. The results indicate that:1 .The main physical and chemical characteristics vary regularly: with rising of the altitude, there is a transition from silt>sand>clay to sand>silt>clay in the mechanical composition; the Argic horizon emerges below the altitude of 1600 meters; the content of organic matter is enrichment, the content of organic carbon of epipedon is higher than 20 g/kg, while the content of organic carbon increases with increasing of altitude, and in the altitude of 3500-3700meters, the soils under the meadow have the maximum content organic carbon; the soils appear acid-slightly acid reaction, the pH decreases appreciably and acid strengthen with increasing of altitude; the soils higher than the altitude of 2500 meters are base unsaturated, indicating the soil leaching is strong, the pH and BS are distinct plus correlated; the contents of SiO2, Al2O3, and Fe2O3 of the soil body and clay areall relatively stabilization; In the soil body, the content of SiO2 is much high and CaO is very little, the total contents of SiO2 , A12O3 and Fe2O3 occupy 92 % of the mineral parts, the sequence of mineral elements is: SiO2>Al2O3>Fe2O3>K2O>MgO>CaO>TiO2>MnO.2.The Diagnostic surface horizons divided on the soils of the area are Mollic epipedon, Umbric epipedon and Ochric epipedon. The Diagnostic subsurface horizons are Cambic horizon, Argic horizon, Histic evidence and Mattic evidence.The diagnostic characteristics are Sapric soil materials, Folic soil materials, Soil moisture regimes, Soil temperature regimes, Ferric property and Base saturation.3.The soils are divided into 2 Order, 3 Suborder, 6 Groups in Soil Taxonomy; The soil vertical zone strcture of south slope Taibai Mountain is : Ferric-Udic Argosols(< 1600m) - Acidi+Ferric-Udic Cambosols(l 600 - 2700 m )- Bori-Udic Cambosols(2700 - 3400 m)-Molli-Gelic Cambosols(3400-3500m)- Umbri-Gelic Cambosols(>3500m).4.The result of Soil Taxonomy consist fundamentally with that of the genetic classification and the boundaries roughly identify with each other, indicating the taxonomic classification is based on the genesis theory and the two classification system are touched tightly. The comparability and otherness are coexist in the text of Soil Taxonomy with numerical analysis method, which indicates that Soil Taxonomy is a kind of more objective and more scientific method for soil classification, and the numerical analysis can be considered as the measure to test the Soil Taxonomy . |
