A Research on Determinating Soil Types and Soil Boundaries under Chinese Soil Taxonomy
|School||Nanjing Agricultural College|
|Keywords||Soil taxonomy Soil survey and mapping Diagnostic layer Diagnostic Characteristics Soil landscape|
The soil survey is the basic means and an important foundation for the research of soil classification, and soil classification can provide theoretical support and direction to soil survey at the same time. The soil taxonomy and soil genetic classification have a significant difference, and the classification of soil genesis lead to the soil type of uncertainty, so China in 1984 began the study of soil taxonomy, After soil scientists nearly 20 years of efforts, China’s soil taxonomy program has been basically formed. Although China has had more mature theory of Chinese Soil Taxonomy system, but no corresponding technical studies of soil survey methods. The purpose of this study is to soil taxonomy theory as a guide, and select a representative area to research about soil survey methods for the Soil Taxonomy. The main research content is identifying to soil types and soil boundaries for Soil Taxonomy. Soil type is carried out conventional cloth-point method to set the location of the main profile point, and from the terrain classification and mapping precision analysis to determine the quantity of the main soil profile, using diagnostic horizons and diagnostic characteristics to determine their names. Soil boundaries is to use the interpolation method in the investigation of the route after the cut-off point, combined with remote sensing images to connect the demarcation point of same type soil from different lines of investigation with smooth curves to determine soil boundary. This study proposes a hope for the Chinese Soil Taxonomy about the method of determining soil types and soil boundaries and fills the vacancy in this area of China.The main results and conclusions of this research are as follows:(1) Determining investigation routes. First, we analysis carefully the landscape data of the study area such as parent material, topography, vegetation maps and land use plans to determine the initial overview of the study area. And then we simulated survey line of indoor using ArcGIS and other GIS software. At last we used the positioning function of GPS field survey carried out in the wild. The density of survey line depends on topography and parent material type and other factors in the study area. Soil survey routes should be along the vertical contours of the study area and as far as possible through different types of vegetation and land area so that to ensure that cover all soil type.(2) The principles of setting profile points. The type of soil profile is divided into the main section, check the profile and delimitation of three types of profiles. This paper describes the specifications of soil mining, using conventional distribution method to determine the location of the main profile points, and naming Primosols, Cambosols, Argosols and Anthrosols our soil orders to "retrieve the Chinese Soil Taxonomy (3rd edition) "in the diagnostic horizons and diagnostic properties of the soil profile to determine standards, and finally establish the main principles of section to set the number of points from the terrain classification and mapping precision.(3) Determining the soil boundaries. We use interpolation search to find soil boundary, select a representative survey routes to dig and name the main profile, the use of checks and delimitation of section profiles to determine cut-off point and to determine the soil line. Preliminary determining investigation routes and the main profile is the basis of soil boundaries determined, the principles of setting check profile and delimitation profile is important to determine boundary conditions.(4) Combining with soil landscape to survey. Landscape factors have a good indicative on soil properties. The paper analyzes the relationship between landscape factors and soil types. We found the terrain slope; land use and vegetation types and other landscape factors played a relatively good correspondence between soil type and nature. They also play a very important role in setting the soil survey, soil profile and finding soil boundaries.The innovation of this paper is that selecting representative small area to carry out detailed soil survey work on the base of Soil Taxonomy as the theoretical. We propose the series of technical measures such as settings of soil investigation route and profile point, finding the soil boundaries so that to better carry out the soil investigation work.