The Theory and Application of the Regulations of Farmland Grading

The Regulations of Farmland Grading is based on crop productivity principle, production factor theory, and land rent theory. The farmland grading is obtained through calculation of potential productivity of farmland, and step by step modification using land use coefficient and land economic coefficient according to the methodology of Agro-ecological zones (AEZ). At different categories, the farmland grading has different application directions. For example, the natural quality index, which is a basis of farmland grading, reflects climate and soil conditions influencing crop growth, as well as the farmland construction status. As one of the most important results of farmland grading, the natural quality index can be applied for every aspects related to land quality evaluation, especially land use planning and the appraisal of balance between cultivated land occupation and supplement. The farmland utilization index is based on the production factor theory. It means that crop yield is not only affected by farmland quality, but also controlled by the inputs and field management. So, farmland utilization index is calculated by multiplying the natural quality index and land utility coefficient. The farmland utilization index reflects the farmer's capacity and willingness to agricultural inputs and management. And the potential of farmland productivity is obtained by comparing the natural quality index and the farmland utilization index, and crop yield could be increased through increasing the inputs and improving management. Farmland economy index is calculated by multiplying the farmland utilization index and land economy coefficient, and the value of inputs, and income and benefit of agricultural production could be analyzed through analyzing the farmland economy index.