Preliminary Study On The Soil Series Survey Methods In Hilly Area By Using Soil-Landscape Models

Chinese soil taxonomy(CST)has made many achievements since 1985;a complete system of senior classification level has been established.At present,our country is in the stage of researching on the most basic taxonomic unit-soil series,the large-scale soil series survey may be carried out in the future.But the soil survey technology in China are based on Chinese genetic classification,because classification systems is different,The corresponding soil survey methods must have difference,Therefore,in order to better serve the soil series survey,it is necessary to carry out the research on soil series survey methods.As the relationship between the soil series distribution and landscape characteristics is closely,landscape is a mirror of soil;we can use landscape variability to probe into the soil series survey methods.As is known to all,using remote sensing(RS)and geographic information system(GIS)technology,landscape can be interpreted efficiently and quickly.Based on this,in this paper,a small-scale area in Ju-rong County Jiangsu Province was selected as the study area.Firstly,use the method of decision tree classification for the classification of land use type of ZY-3 satellite,then overlaid the raw image with the classification results in the EN?4.8,and then compared to the field investigation to correct the result by the way of manual interpretation.Taking the revised land use type map as the basic map when the precision met the requirements,then the elevation and slope information was added by the method of decision tree classification,finally,the"elevation-slope-land use type" landscape map was generated.The Digital Elevation Model(DEM),ZY-3 satellite and landscape classification map were combined to study and discuss the choosing of survey line,the setting of the main soil profiles,and the searching for soil series boundary at the large scale of soil series investigation based on the relationship between soil and landscape,then soil series surveys were conducted in the core area to verify how useful and reasonable this method is.16 soil series were established in the core area and explore the relationships between soil series or its property and landscape,as we predict soil distribution or soil type more accuracy,it is not enough only rely on the image,it is necessary to explore the relationship between soil and landscape deeply.Finally summarize the content,draw relevant conclusions about the soil series survey methods and suggestions.Main results of this study are as follows:(1)the choosing of survey line:Method for choosing survey line through comprehensive analysis of the elevation map,remote sensing image and the landscape classification map,as taking the elevation,slope,land use type etc,into account,this method is more objective than traditional methods,when carry out the soil field exploration,we can obtain more landscape information.In this way it can provide better reference for setting soil profiles or searching for soil boundary.(2)the setting of the main soil profiles:use the "elevation-slope-land use type" landscape map to set soil profiles based on the principles of main soil profiles setting number of the traditional soil survey,not only consider the elevation,slope,land use and landscape factors that may cause the soil type changes,but also conduct classification landscape statistics and distribution.This method takes the variation of the landscape into account,let different landscape have reasonable profiles,it makes profile settings more representative.The survey results also confirmed that the main profiles setted in this way basically covers all soil series types,sixteen soil series is established in the core area,thirteen soil series can be found in this way,which basically covers all soil series types.But if use the method of regular grid points,the same amount of soil profiles,only cover seven soil series,the facts show that this method that consider the landscape variation to set profiles has a huge advantage than the traditional uniform grid method.(3)The searching for soil series boundary:It is easy to find the place where the landscape factor changes tempestuously via image classification,the results also confirm that the place where the landscape factor changes tempestuously is often the soil series boundary,but we need pay special attention to grasp the main landscape factors.The places that slope change or land use change are a sensitive area in the core area The change of elevation reflects the trend,the boundary of higher terrain and moderate terrain is also the boundaries of talus material and xiashu loess,so the soil series boundary is apparent,in other places the trend is not clear.(4)Field survey showed that the distribution of soil,the soil properties correspond well with landform,parent material,land use type,elevation,slope and so on.For example the soil series that has gleyic features in Stagnic Anthrosols is mainly distributed in shallow ground water level,low-lying field paddy field.Udic Argosols is mainly distributed in forest land,the slope has a certain effect on the position of claypan,the soil in the pinus massoniana forest or strongly sloping or steep hills is acidic,the soil series that has Ferric property and acidic in Udic Cambosols is distributed in the old tea garden.Orthic Primosols is distributed in steep hills,the soil body is shallow,and the whole soil profile is acid etc.The in-depth study of landscape can guide the soil investigation work and determining soil types in Chinese Soil Taxonomy.