利用图层叠加求交的方法，把合水县土壤图、农用地地块图和行政区划图叠加求交，得到5 487个评价单元。选取2012年≥10 ℃积温、年降水量、有机质、有效磷、耕层厚度、剖面构型、地貌类型、坡向和坡度作为评价指标，采用层次分析法建立层次分析模型，采用特尔斐法和隶属函数拟合法确定各评价指标的隶属度和隶属函数，最后使用县域耕地资源管理信息系统加法模型计算耕地地力综合指数IFI，通过IFI大小来划分合水县耕地地力等级。结果一等地综合评价指数IFI＞0.920 0，占耕地总面积的2.71%；二等地IFI为0.920 0～0.885 0，占16.93%；三等地IFI为0.885 0～0.725 0，占45.58%；四等地IFI为0.725 0～0.625 0，占26.82%；五等地IFI＜0.625 0，占7.96%。

By using the method of the layer stack intersection， put the soil map， agricultural land block diagram and the administrative zoning map of the Heshui county superposition of intersection to get 5 487 evaluation units . The accumulated temperature≥10 ℃， annual precipitation， the organic matter， the effective phosphorus， top layer thickness， profile configuration， geomorphic types， slope aspect and degree were selected to be the evaluation index， using analytic hierarchy process to establish the analytic hierarchy model， Delphi method and membership function fitting method to get membership and membership function of each evaluation index . Finally， using cultivated land resource management information system of the county additive model to calculate IFI， according to the number of IFI to divide the farmland productivity level of Heshui county . The first-grade arable land IFI is bigger than 0.920 0， accounting for the total area of cultivated land 2.71%； The second-grade arable land IFI is 0.920 0～0.885 0， accounting for the total area of cultivated land 16.93%； The third-grade arable land IFI is 0.885 0～0.725 0， accounting for the total area of cultivated land 45.58%； The fourth-grade arable land IFI is 0.725 0～0.625 0， accounting for the total area of cultivated land 26.82%； The fifth-grade arable land IFI is smaller than 0.625 0， accounting for the total area of cultivated land 7.96% .

S158

甘肃省科技支撑计划项目(1104NKCA093)