粮食安全与生态安全双约束下江苏省耕地休耕规模探讨

实施耕地休耕是巩固提升粮食产能和促进农业可持续发展的重要举措,亟需科学合理地确定我国可休耕耕地规模,为深入实施"藏粮于地"战略和扩大耕地休耕制度试点提供理论依据。该研究基于粮食安全与生态安全双重约束构建粮食主产区耕地休耕最大规模测算仿真模型,同时提出休耕规模弹性边界的确定方法并以江苏省为实证区域进行仿真预测。结果表明：当前江苏省在兼顾粮食主产区的粮食调配任务且考虑区域耕地资源可持续利用状况的基础上,仍能保有10.16%的耕地资源来支撑耕地休耕制度的实施;仿真期内区域耕地资源面积可能会由于城市快速扩张和耕地保护不力出现大幅减少,并对区域耕地休耕条件环境产生影响;同时耕地资源可持续利用状况和休耕规模适宜程度的恶化导致江苏省休耕规模弹性边界从2017年的9.93%缩减至2036年的4.81%,区域粮食安全稳定状态终将被打破。建议充分利用粮食主产区的耕地资源基础积极有序推广开展耕地休耕工作,深入部署"藏粮于地"战略以巩固提升粮食产能;建立休耕规模与生态安全挂钩的指标预警体系以实现对休耕实施方案的宏观动态调节;统筹休耕与其他耕地保护政策的正向联动,创造耕地保护政策体系内部的正向溢出效应。

Fallow scale of major grain producing areas in Jiangsu Province under food security and ecological safety constraints

Fallow is a significant and effective measure to improve agricultural production capacity, promote sustainable development of agriculture, as well as drive strategy for rural revitalization in China. Since scientific determination of fallow scale is the common concern problem in the research field of fallow, it''s highly urgent to study what the exact fallow scale threshold is so that scientific basis can be provided to deeply carry out the national strategy of "Storing Grain in Land" and expand fallow pilot scheme on a national scale. The superior basis condition of cultivated land has help major grain producing areas play significant roles in ensuring the national food security, while the long-term intensive utilization of cultivated land has also caused land degradation and ecological environment deterioration. By introducing the revising pressure index on cultivated land and ecological balance index, the study aimed to build a model with general applicability to estimate the largest fallow scale of major grain producing areas under both food security and ecological safety constraints, meanwhile an approach of determining the elastic boundary of fallow scale is also presented. Then Jiangsu Province was selected as the empirical area and System Dynamics model was employed to simulate and forecast the variation tendency of the largest fallow scale as well as elastic boundary of fallow scale. The results showed that: 1) during the simulation run from 2007 to 2016, the elastic boundary of fallow scale would shrink from 12.12% in 2007 to 10.16% in 2016, a certain proportion of flexible cultivated land resource can still be held in Jiangsu Province to support the implementation of fallow system when the grain distribution mission was accomplished and the ecology of cultivated land resource was also taken into consideration; 2) during the simulation run from 2017 to 2036, the cultivated land resource in Jiangsu Province would decrease to 446.63×104hm2with the rapid urbanization process and the implementation of land protection measures may have little effect to avoid the over-fast loss of cultivated land. In addition, the condition and environment of fallow would also be broken because of the deterioration of cultivated land resource ecology; 3) during the simulation run from 2017 to 2036, because the sustainability of cultivated land resource and fallow suitability index would both continue to decline over time, the maximum fallow scale and elastic boundary of fallow scale would both decrease over half at the end of the simulation, sustainable use of cultivated land appears to be less optimistic. Taking both food security and ecological safety into consideration, it was suggested to take full advantage of solid foundation of cultivated land resource in major grain producing areas, and implement normalized fallow actively and orderly. Great importance should be attached to the potential ecological security risks of cultivated land resource in major grain producing areas, the early warning index system link up with food security and ecological safety should be built to dynamically adjust the fallow scheme. Besides, the fallow system and other cultivated land protection policies, such as abandoned farmland management, land consolidation and farmland capital construction, should be aligned to make overall plans, so that positive spillover effects can be created in the internal cultivated land protection system and further promote cultivated land ecosystem through the implementation of fallow.