中文摘要：

[目的]分析生态退耕前后农牧交错带耕地利用的可持续性。[方法]以宁夏盐池县为案例区，利用土地利用类型的年转移率、耕地适宜性特征和能值分析，定量分析在生态退耕前后耕地利用可持续性的变化特点。[结果]建设用地扩展占用耕地的趋势逐渐增强；生态退耕后，耕地面积仍然大于宜农地面积；耕地农业化学物质的投入逐渐加大，单位种植业能值产出所需的农业化学物质能值投入不断增加。耕地利用的可持续性波动降低。[结论]监管建设用地的开发和利用、深化生态退耕政策，根据降雨量控制单位种植业能值产出所需的农业化学物质能值投入是提高农牧交错带耕地利用可持续性的主要方向。

英文摘要：

[Objective] This study aimed to analyze the sustainability of cropland use in cropping-pastoral ecotone before and after the Grain-for-Green Policy. [Method] Using Yanchi County in Ningxia Hui Autonomous Region as a case study area, this investigation used the annual transfer rate of land use types, cropland suitability and emergy analysis to examine the major pressures affecting the sustainable use of cropland before and after the Grain-for-Green Policy. [Result] The expansion of con- struction land onto cropland was significant; the annual cropland area was still larger than the land area suitable for cropping after the policy; agrochemical inputs used for crop production gradually increased and unit crop outputs required more agro- chemical inputs. Cropland use sustainability showed a fluctuating downward trend. [Conclusion] The results imply that the protection of high quality cropland, further im- plementation of the policy and control of agrochemical inputs according to precipita- tion are the main measures needed for sustainable cropland use in cropping-pastoral ecotone.