Division of key cultivated land regions based on calculation of comprehensive productivity in Hebei province

The essential of protecting the cultivated land was to protect the comprehensive production capacity. It was the fundamental measure for ensuring resources security and sustaining productivity stability of the cultivated land to divide the cultivated land into different ranks according to the production capacity. The theoretical production capacity of cultivated land was obtained from the linear regression model which was established with the relationship of the natural quality ranks and the standard crop yield per unit from theoretical sampling investigation data on the basis of agricultural land classification. And the practical production capacity of cultivated land was obtained from the linear regression model established with the relationship of the land use quality ranks and the standard crop yield per unit from practical sampling investigation data. Then the scale advantage index and the aggregated advantage index of cultivated land were put forward to analyze the spatial distribution pattern of comprehensive productivity. Combing with the future potential productivity, current productivity and the input and output status, cultivated land in Hebei province was divided into four protective classes. The first class was the state-level protection region. The area was 2.02×106 hm2 which accounted for 32.1% of the total area. The second class was the provincial-level protection region and the area was 2.98×106 hm2. The third-level protection region was the municipal-level protection region which accounted for 30.1% of the total cultivated land in Hebei province. The rest was classified as the fourth-level which accounted for 9.7% of the total area. By the division of protected regions and definition of the protective duties of different subjects, it was of great realistic meanings to stabilize agricultural production and to ensure food security.