| Cropland is the rare resource. Land pressure from human activity is more and more heavy. In order to make rational use of and optimize the land resource, and to promote sustainable use of cropland, cropland quality evaluation is necessary for decision making of governor and land users. Taking Houhu Farm in Jianghan plain as an example, the evaluation indicators system of study area is established according to the basic principles of cropland evaluation with the mathematics methods used. Then the cropland quality assessment in study area is developed by using Geographic Information System (GIS) technology and based on the cropland quality indicator system. The mam achievements of this research are shown as follows:1. Establishment of the indicators system of cropland evaluation in Jianghan plainBased on The Cropland Classification Rule constituted by National Land Resources Ministry of China, and combined with local fact of cropland, 25 indicators of cropland quality are choosed as the preelection indicators, including the geography, soil, regional location, fundamental facilities, transportation and resources etc. The Delphi method and the princomponent analysis method are adopted to select indicators that can be adjusted to this area. The research results show that 17 of the 25 indicators are effective. Among the 17 indicators, soil quality, obstacle layer, irrigation, underground water level and transportation are more important than others. Their weights are 0.067, 0.067, 0.065, 0.064 and 0.06 respectively.2. The grading evaluation of the farmland in Houhu Farm in Janghan plain After the indicators system and indicators database established, fuzzy setmethod and FNN (Fuzzy Nerve Net) method are used to evaluate the quality of Houhu farmland. By comparing the results obtained from above-mentioned two methods, FNN are proved to be more available. The main grade of the farmland is level 3, whose area amounts to 1.43 107m2, occupying 45% of the evaluated area in the farm. Among the six producing units of the farm, the quality of Qianhu is thebest, mainly composed by the second and first grade, the areas of them are 46% and 37% of the producing unit area respectively; The main grade of Tianxin, Guanmiao and Liutang is in third grade, the areas of them are 65% , 75% and 60% of each producing unit area accordingly; Moreover, the land quality of Guanmiao is better than that of Liutang. The land quality of Huangzhuangyuan and Zhangjiayao is the worst in the farm. The area of the fourth grade in Huangzhuangyuan is 61% of this producing unit area, and the area of the fourth grade in zhangjiayao is 77% of this producing unit area. Viewed from the grading graph, the fourth grade lands are distributed at the northeast and the southwest of the farm. The third grde lands are mainly located at Tianxin, Guanmiao and Liutang. The second grade lands are distributed at both sides of the first class ditch. The first lands are distributed at east and southeast of Qianhu producing unit. The grade distribution graph shows that the land quality is related to the soil quality, soil obstacle layer, irrigation, the underground water level and other indicators.3. Comparative analysis of weight of land appraisal indicatorsCompared the weights calculated by the princomponent method and FNN method, the research results illustrate that the weight order of indicators is the same, but the values of FNN are more available than that of princomponent analysis method, and is in0.077 to 0.002). Furthermore FNN can avoid the artificial influence on weight decision.4. The environmental Quality evaluation of farmland in Houhu Farm in Jianghan plainIn view of the fuzzy attribution of land resource, the environmental quality of the farm is evaluated by using fuzzy set method. The research results show that synthesis pollution index is under the contaminative level, but there is 40.81% of the farmland soil area on the critical line of pollution. Specified to the individual pollution index as B, Cd and pesticide ar...
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