Classification And Reference Of Felty Soils In Qinghai Province Based On Multi-Classification System

Soil classification is the foundation and core of soil science research.Grass felt soil is widely distributed in the Qinghai-Tibet Plateau of my country.The vegetation form is mainly alpine meadow.The grassland in Qinghai Province has a wide spatial distribution and a large area.The grass felt soil is mainly distributed in the Sanjiangyuan and Qilian Mountains.Utilization and protection of the ecological environment play a vital role.In this paper,the distribution area of Felty soils in Qinghai Province was selected as the research area,and 31 Felty soils profiles in the area were taken as the research objects.The soil-forming environment,profile shape and physical and chemical properties were analyzed,and Genetic Soil Classification of China(GSCC)was selected.The five soil system classifications include the Chinese Soil System Classification(CST),the American Soil System Classification(ST),the United Nations World Soil Legend Unit(FAO/UNESCO)and the World Soil Resources Reference Base(WRB).According to the classification principles and standards of different classification systems,the diagnostic horizons and diagnostic characteristics are identified,and the classification attribution of Felty soils in each classification system is determined by level retrieval,and soil genetic classification and soil taxonomy,as well as the reference between soil taxonomy,are established respectively.The fuzzy c-means algorithm model is used for numerical classification,and compared with the soil taxonomy to analyze the rationality of the soil taxonomy.Concluded as follow:(1)According to the Genetic characteristics of soil profile and relevant experimental data,the specific attribution of Felty soils in Qinghai Province in various soil classification systems was determined.According to the Genetic Soil Classification standard of the second national soil survey,all profiles are divided into4 subgroups according to the genetic classification: Felty soils,thin Felty soils,brown Felty soils and wet Felty soils.According to CST,all sections were diagnosed with 7diagnostic horizons: Ochric epipedon,Mattic epipedon,Histic epipedon,Mollic epipedon,Calcic horizon,Cambic horizon,and permafrost layer and Gleyic features,Frost-thawic features,Calcaric property,Redoxic features,L.C.of red sandstones,Lithic contact,Soil temperature regimes and Soil moisture regimes 8 diagnostic characteristics,which are divided into Histosols,Gleyosols,Primosols,Primosols 4Orders,and 5 Suborders,10 Group and 14 Subgroups.According to ST,7 diagnostic horizons including Mollic Epipedon,Histic Epipedon,Ochric Epipedon,Argillic Horizon,Cambic Horizon,Calcic Horizon,Permafrost.And 5 diagnostic characteristics including Identifiable Secondary Carbonates,Calcareous,Lithic Contact,Soil Temperature Regimes,Soil Moisture Regimes.Divided into 3Orders(Gelisols,Inceptisols and Primosols),6 Suborders,6 Groups,and 10 Subgroups.According to FAO/UNESCO,a total of 6 diagnostic horizons were divided: Histic H Horizon,Mollic A Horizon,Ochric A Horizon,Argillic B Horizon,Cambic B Horizon,Calcic Horizon.And 3 diagnostic characteristics CALCAREOUS,Gleyic and Stagnic Properties,Permafrost.Divided into 5 first-level units(Cambisols,Calcisols,Gleysols,Histosols,Regosols)and 7 second-level units.According to WRB,a total of 7 diagnostic horizons(Argic horizon,Calcic horizon,Cambic horizon,Cryic horizon,Histic horizon,Mollic horizon,Ochric horizon)and 5 diagnostic characteristics(Gleyic properties,Permafrost,Secondary carbonates tagnic,Properties,Calcaric material permafrost)were diagnosed,divided into 6 first-level units(Cambisols,Calcisols,Gleysols,Histosols,Cryosols,Regosols)and 19 secondary units.(2)According to the attribution and reference of Felty soils in each classification system,soil system classification uses quantitative means to classify soils,making the classification more clear and objective.The classification criteria of each classification system are similar.In CST,ST,and WRB,the level of soil class can basically be one-to-one correspondence,and it is difficult to correspond to subgroups and lower levels.The naming method of CST and ST is the closest.WRB puts some attributes such as soil texture and land use mode into supplementary modifiers as limiting conditions,while in CST,texture,calcareous,acidity and alkalinity,and soil temperature are used as the criteria for judging the soil family.FAO serves digital soil mapping with a relatively simple classification level.It is suggested that CST should increase the soil type retrieval conditions or grades of Gelic Cambosols to meet the condition that some sections have both Mattic epipedon and the permafrost layer;The subgroup of "Mattic Gelic Orthic Primosols" is added to solve the problem that C horizon is below the Mattic epipedon;It is suggested that the corresponding soil category of Felty soils should be added in the international classification system.(4)This paper uses the fuzzy c-means algorithm model to divide 31 Felty soil profiles into 8 central subcategories.The selection of appropriate classification factors and number of classifications became the key to numerical classification.There is a significant difference between the classification results and CST.It is suggested to increase or improve the diagnostic horizons and diagnostic characteristics,and add limited conditions to distinguish soil types,so that the differences between types are more significant,and the types division is more reasonable.