Structure, Contents and Possible Applications of China National Soil Information System

Soil Information System (SIS) is a computerized tool, which is built to collect, store, manage and analyse soil and soil-related environmental information. The establishment of SIS is the consequence of the development of soil science, for it is absolutely necessary for the evaluation of soil resource and natural resources as well as the modelling of ecological processes. This paper analyses the national and international progress in the research and establishment of soil information system, the features of the spatial databases and the attribute databases of the global and several national soil information systems. Most of the national and international soil information systems contain spatial and attribute databases, while NASIS (National Soil Information System, USA) contains, up to now, only attribute data. Attribute databases are mostly relational but NASIS does use UNIX-based INFOMIX system. The features of the design, functionality, structure, contents and possible applications of the being-built China national soil information system are explained. The functionality of national soils information system includes management, assessment and analysis of soil information. It can provide soil information for soil classification, sol science education, soil resource monitoring, soil process and change prediction as well as agricultural and environmental policy-making. China national soil information system comprises three main components, namely the spatial database, the attribute database and the application models. The main data source comes from the Second National Soil Survey Programme as well as from the study of Chinese Soil Taxonomy. The spatial database consists of a series of soil maps and the related thematic maps in the scale of 1∶4,000,000 and 1∶1,000,000 for national level, 1∶500,000 for provincial level and 1∶50,000 for county level. For national and provincial levels, all existing maps will be collected and input into the system, while only a part of county maps can be collected and built into the database in the current stage, due to the mass workload. Spatial data is stored as convertible polygon format as digitized with the current commercial GIS software such as ARC/INFO or MAPGIS. Attribute data is maintained by relational database tool. A unique linking code is built to link the spatial and attribute databases so guarantee the flexible extraction and display. An application model pool containing various models for interpretation is also included, which is equally important for a complete information system. The utility of soil information system varies. For agriculture and forestry, it provides basic information for the recognition of the spatial variation and serves the evaluation of crop (including tree) suitability and, helps to facilitate the implementation of soil conservation projects. For environmental protection, it makes up the necessary part of basic databases to assess environmental capacity and to model environmental processes, regionally and globally. Construction engineering also to seems require more and more site soil information. An example is given to illustrate the main procedures modelling regional pollutant load using soil infromation system and other related databases.