An Assessment Model of the Policy of Dynamic Balance of Farmland Area
耕地总量动态平衡评价模型初探

To protect continuously decreasing cultivated land areas in China, the central government has implement a series of laws and polices, which to a large extent slowed down the rate of land transition from agricultural to construction use. The policy of dynamic balance of farmland area (DBFA) is one of the most important policies for cultivated land protection. Developing an assessment model for the dynamic balance of farmland area was thus of necessity for the smooth and effective implementation of related policies. It was suggested that the assessment model be set up not only the quantitative balance standard of farmland based on regional economic, social and environmental characteristics for a specific area, but also the qualitative balance standard of farmland which might vary at different temporal and spatial scales. Through developing the assessment model for dynamic balance of farmland area, the implementation effects of the policy could be effectively evaluated and existing problems could be identified. Improvement on the policy could be made accordingly. In this paper, the history of the policy of dynamic balance of farmland area was first reviewed and the content of dynamic balance of farmland area was summarized and discussed in succession. It was pointed out that in the implementation process of the policy of farmland area, quantity balance could not be realized at the price of quality loss, i.e., quantity and quality balance should be achieved at the same time. Since temporal and spatial characteristics of a specific region might change, quantity and quality balance might have different standards and even beard different meanings. In the context, an assessment model for the evaluation on dynamic balance of farmland area was developed. The model consists of two sub-models, one focusing on the quantity balance and the other on the quality balance of farmland. Due to an irreversible trend in land transformation from cultivated land to construction land under the circumstance of the rapid urbanization in China nowadays, the quantity balance sub-model was on the basis of the concept of reasonable deviation of farmland area (DCArea). If the net farmland transition area (farmland loss) was less than that of DCArea, it would be considered acceptable and quantity balance was believed to be achieved. The quality balance sub-model justifies the balance by the trends of the input and output of farmland. If the output increases at a higher rate than does the input, or if the output decreases at a lower rate than does the input, the qualitative balance is thought to be achieved. The assessment model was used for the evaluation on policy implementation in Jiangsu province during the period from 1999 to 2006.