| The gray-forecasting model is used to study the major crops, i.e. wheat, maize, soybean, oil crops, cotton, and vegetables, in ten counties located in the plain of southern Hebei province along 38° line, and thus the values of the ecological services of the crops are calculated; and then with the target matrix formed by the values as well as the water consumption and production cost per unit area, the gray-forecasting model of condition decision is adopted to study the methodology to decide the spatial allocations of the major crops in the concerned areas. Meantime, the suitable areas for planting different crops are illustrated and will function as the scientific basis for the structural adjustment of crop production in the concerned areas. |