| Soil is the fundamental of agricultural production and land is the unsubstitutional product material that all the people rely on. Its environmental quality has a direct influence on agricultural structure, land output and quality of its produces. Along with the development of society and the increasingly pressure from population, resources and environment, the demands of agricultural produces and its quality are heavier and heavier. Land, along with population, resources, environment and foodstuff is becoming the hot issue attracting the focuses of the entire world. In order to gear to the agricultural structure adjustment, promote non-harmful agricultural produces, keep sustainable development of agriculture and enhance the general productivity of land, it's urgent to conduct a comprehensive survey on soil quality and its environmental conditions. Only when we have an all-sided understanding of the land fundamental capacity, soil fertility, environmental conditions and soil obstacles can we work out scientific specifications and regulations for safe agricultural production, agricultural sustainable development and soil improvement and proper use. This dissertation, taking E Zhou city of HuBei province as an example and employing advanced technology of computer and GIS (Geographical Information System) carried out the survey of land capacity and its assessment. Some of the achievements of this dissertation can be summarized as follows:1. Soil fertility assessment. This paper takes Ezhou city of Hubei province as an example as a case study, collects and standardizes relative information of maps, data, texts and multimedia documents. The assessment units are created by overlaying soil map with land use map. The indicators are backed with various parameters such as organic matter, available K, available P, texture, PH, CEC, thickness of arable layer, underground water level in winter, mother material of soil, slope aspect, crop system, drainage ability and soil obstacles. The weight of indicators has been calculated by using Analytic Hierarchy Program (AHP). The spatial and attribute databases were established. Assessment models are to be applied via carrying out soil fundamental fertility grading as follows: grade one 1462.5ha, grade two 7692.1ha, grade three 16079.3ha, grade four 12733.6ha, grade five 2625.7ha and grade six 299.2ha, sharing each percentage as 3.6%, 18.8%, 39.3%, 31.1%, 6.4% and 0.7%, respectively.2: Recommended fertilization. Research to address field soil nutrient grade was conducted with GIS (Geographical Information System) in DuShan country of Ezhou city. Located by GPS, 134 field soil samples from the field's surface to 15cm depth were collected on 500-by-500-m grids. Five soil chemical properties such as organic matter, available N, available P, available K and pH were chosen as factors to evaluate the gradeof soil nutrient and were determined as well. Field soil nutrient was divided to five grades according to the method of comprehensive scoring. This paper also made steps into the research of improved recommended fertilization based on soil nutrient rating results.3. Issue of the maps via Internet. WebGIS emerged with the advance and interaction of technology of Web and GIS, thus broaden ways of information distribution and also make information sharing easier. This thesis discussed the establishment of land capacity information system at city level based on ArcIMS. The system is designed with the model of Browser/Server so that the users can conveniently access the information with Internet explorer. The system realized the query of landuse, soil distribution, soil fertility distribution and land capacity grades, zoom of the maps at any extent without distortion. Some spatial analysis functions such as buffer analysis and distance measurement were also added to the system.
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