Multi-scenario comparisons to identify the spatial distribution, land type, and effectiveness of cultivated land restoration in the main grain-producing area

Cultivated land protection plays a pivotal role in ensuring grain security. Although China has managed to halt the continuous decline in the total amount of cultivated land over the years, some of the complementary cultivated land is of poor quality. Therefore, China still needs to strengthen cultivated land protection by implementing cultivated land restoration (CLR). However, current studies on CLR have certain limitations, as they neglect the multidimensional perspective of cultivation suitability evaluation (CSE) and fail to prioritise specific types of secondary land for restoration. In this context, based on a theoretical analysis of the objects, connotations and objectives of CLR, focusing on the Chengdu Plain, China's primary grain-producing area, this study devised four CLR scenarios: the priority to sustainable use scenario (PSS), the priority to cost scenario (PCS), the priority to ecological health scenario (PES), and the comprehensive restoration scenario (CRS). These scenarios aimed to address three key questions about CLR: where to restore, what to restore, and how effective it is. The findings revealed that areas with high cultivation suitability values were located predominantly in flat regions with favourable natural conditions. Garden land and forest land emerged as the primary sources for CLR, with restored paddy field being more widely distributed, while restored irrigated land and dryland were concentrated in specific parts of the study area. Besides, the restoration of cultivated land led to a significant increase in grain production across all scenarios, with optimal resource allocation. Notably, the PSS scenario demonstrated the most promising results, resulting in a remarkable 59.20% increase in grain production. Therefore, we emphasise that the scientific CLR implementation is of great significance to cultivated land protection in China at this stage, and we advocate for conducting CSE and managing all potentially arable land (PAL) with a focus on sustainable use. Overall, this study offers valuable insights that can serve as a reference for other countries or regions facing similar challenges, such as limited per capita cultivated land and variations in land quality, regarding CLR and the sustainable management of agricultural land.