| The large population base with a low per capita coverage of land in China, especially the less cultivated land, caused a dramatic conflict between human and land. In order to strengthen the effective administration of farmland, have a coordinated and sustainable development among population, economy, society, environment and resources,we must grasp the basic condition of cultivated land resources through investigation before we make full use of them. The research selected Yang Xian in Shaanxi Province as the study area. With the assistance of some software such as ArcGIS, Geoway and resources evaluation system for agricultural lands in county level, it combined analytic hierarchy process, fuzzy mathematics method, Delphi method and the membership function method to screen evaluation factors, determine the weight and factor score, and also construct the membership functions. It used the technology of GIS to build database, combined with accumulation model to calculate the integrated fertility index (IFI) of cultivated lands, and further determined the classification of the arable productivity using the method of distribution curve grading. The arable productivity of Yang County has been investigated and analyzed. The results are compared and studied as follow:(1) According to the comprehensive index of the cultivated land fertility and the actual condition in Yang County, the arable productivity there can be classified into six grades. Further calculated the areas of the cultivated lands in each grade using ArcGIS, we got the thematic map of the arable productivity classification in Yang County. The areas of each grade are as follows: the first grade of the cultivated lands is 4367.34hm2, accounting for 8.67% in the cultivated lands of the whole County; and 17.90% reaches grade two, which is 9020.37hm2; 29.62% reaches grade three is 14924.84hm2; 23.82% reaches grade four is 14924.84hm2; 12.51% reaches grade five is 6303.17hm2; and the grade six is 3772.11hm2, accounting for 7.49%.(2)The first level soil is distributed in valley plains which are better irrigated andin a lower altitude. Most of the soil there is Paddy Soli, which contributes about 4412.18hm2 , and a small part of Yellow Brown Soil for 245.15hm2. 81.55% (3561.55hm2) of the soil is used as farmland which has a small slope below 3°.99.3% (8957.47hm2) of the level 2 farmlands is also distributed in valley plain which are better irrigated and in a lower altitude. Only a small part, 0.7% (62.91hm2) is in hilly areas. The Paddy Soil there accounts for 54.9% (4952.28hm2) and for Yellow Brown Soil,43.61% (3933.96hm2). Besides, there are also Clayloamycar-aqui-alluvic Soil and Chao Soil. 82.8% (7468.73hm2) of the level 2 farmlands is below 3°,and only 1551.64hm2 are beyond 3°.Level 3 farmlands are distributed in all landform. 61.44% (9170.12hm2) is in valley plain, and 31.66% (4725.93hm2) is in hilly areas, only a small part is in mountain areas.The main soil types are Yellow Brown Soil and Paddy Soil, the former accounts for 56.71% (8463.81hm2) and the latter 34.93% (5212.96hm2). 67.25% (8071.73hm2) of the level 4 farmlands is in hilly areas, then 27.94% (3353.25hm2) in valley plain. Only a small part is in mountain area. 83.19% (9985.59hm2) is Yellow Brown Soil which takes up the largest proportion and then 13.27% ( 1593.03hm2) is Paddy Soil.The distributionof level 5 farmlands is familiar to level 4 farmlands. 64.06% (4038.11hm2) is in hilly areas, then 35.49% (2237.01hm2) is in valley plain, only a small part is in mountain area. Among several soil types, Yellow Brown Soil is the most kind, which accounts for 94.91% (5982.37hm2), then there are also Paddy Soil, Clayloamycar-aqui-alluvic Soiland Brown Soil.As for the level 6 farmlands, 70.39% (2655.15hm2) of it is in hilly areas, then 19.59% (738.92hm2) is in valley plain, the left 10.02% is in mountain area. All level 6 farmlands are distributed in a slope beyond 7°, and Yellow Brown Soil accounts for 99.12% (3739.05hm2), besides, there are Paddy soil and Clayloamycar-aqui-alluvic Soil.Finally, the essay proposes some recommendations of the rational use and improvement of the cultivated land in Yang Xian aimed at the major problems exist.This paper initially explores a set of effective measures to investigate and evaluate the arable productivity, process the data, with the assistance of some software like GIS. And it has a positive significance in the scientific management and use of the cultivated land resources in China.
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