On The Genetic Characteristics Of Upland Soils In Southern Hunan And Their Attributions In Chinese Soil Taxonomy

Soil genetic classification and soil taxonomy are the basis for understanding soil and soil resources investigation,mapping and evaluation.Currently,standardization,quantification and unification of soil characteristics have become a major trend of international soil classification.In order to ascertain the occurrence characteristics of typical Upland Soils in Yongzhou and Chenzhou regions of Hunan Province(hereinafter referred to as southern Hunan Province)and their attribution in Chinese Soil Taxonomy,16 typical Upland soil profiles with five different parent materials of limestone,slate,sandstone,granite and purple stone area in southern Hunan Province were studied.The main occurrence characteristics of Upland Soils in southern Hunan were studied by field surveying,laboratory analysing and mineralogical analysis.Based on the keys to Chinese Soil Taxonomy(3rd edition),the diagnostic horizons and diagnostic characteristics of soil profiles were identified and their attribution in chinese soil taxonomic classification was determined.The results show that:(1)Based on the stadistics of the data on longitude and latitude,elevation,annual average temperature and annual average soil temperature of 83 meteorological stations in Hunan Province,the estimation formula of soil temperature in Hunan Province is simulated,and the formula is y=37.013-0.027×E-0.516×N-0.004×H,and determined that 16 typical dry land soil profiles in southern Hunan belonged to the thermal soil temperature status.The diagnostic index of soil temperature in soil taxonomic classification is quantified.The distribution of soil temperature in southern Hunan provides basis and support for the establishment of soil temperature status in soil taxonomic classification,and provides reference for agricultural production guidance and basic research in southern Hunan.(2)According to the classification principles and methods of the keys to Chinese Soil Taxonomy(3rd edition),16 typical Upland soil profiles of limestone,slate,sandstone,granite and purple stone area in southern Hunan were retrieved.It has been found that there are the following diagnostic horizons such as ochric epipedon,umbric epipedon,LAC-ferric horizon,argic horizon,and cambic horizon,and the diagnostic characteristics and diagnositc evidence such as paralithic contact,alic evidence,ferric property,perudic soil moisture regimes,udic soil moisture regimes and thermic soil temperature regimes,etc.(3)According to the diagnostic faults and diagnostic characteristics of 16 typical dryland soils,it can be divided into four orders,i.e.Ferrisols,Argosols,Cambisols,and Entisols;five Suborders,i.e.Udic Ferrisols,Udic Argosols,Perudic Cambisols,Udic Cambisols and Orthic Entisols;seven Groups,i.e.Alliti-Udic Ferrosols,Ali-Udic Argosols,Ferri-Udic Argosols,Ali-Perudic Cambosols,Ali-Udic Cambosols,Ferri-Udic Cambosols,Usti-Orthic Primosols;nine Subgroups,i.e.Mottlic Alliti-Udic Ferrosols,Typic Alliti-Udic Ferrosols,Typic Ali-Udic Argosols,Red Ferri-Udic Argosols,Ferric Ali-Perudic Cambosols,Typic Ali-Udic Cambosols,Red Ferri-Udic Cambosols,Typic Ferri-Udic Cambosols,Typic Usti-Orthic Primosols.(4)According to “Chinese classification standards of soil family and soil series”,seven soil families,such as clayey kaolinite non-acidic thermic-Typic Ferri-Udic Cambosols(43-CZ03)and so on,and seven soil series such as xianghua series(43-CZ03)and so on,have been established for limestone soils;two soil families,such as clayey silica mixture thermal-Typic Ali-Udic Argosols(43-CZ08,43-YZ01)and so on,and three soil series such as dashi series(43-CZ08)and so on,have been established for slate soils;Three soil families including Clayey loamy silica mixture thermic-Typic Ali-Udic Cambosols(43-YZ02)and so on,and three soil series such as qingjiaruo series(43-YZ02)and so on,have been established for sandstone soil;two soil families,such as Clayey loamy silica mixture thermic-Ferric Ali-Perudic Cambosols(43-CZ01)and so on,and two soil series such as shangdong series(43-CZ01)and so on,have been established for granite soil;one soil families including loamy silica mixture non-acidic thermic-Typic Usti-Orthic Primosols(43-CZ07)and so on,and one soil series such as songbai series(43-CZ07)and so on,have been established for purple stone area soil.(5)By comparing the attribution of tested soils in taxonomic soil classification and in genetic soil classification,there is often a more-to-one situation.taxonomic soil classification can more accurately,quantitatively and objectively reflect the differences and similarities of soil properties in southern Hunan,thus avoiding the problem of homonymy between different soils.