Mapping the potential of rapeseed growing in winter fallow fields across the Yangtze River Basin in China

The Yangtze River Basin (YRB) is the world’s largest rapeseed production area. Nevertheless, winter fallow fields in this region decrease land use efficiency and rapeseed production. Therefore, it was important to precisely delineate the suitable areas for rapeseed growing and evaluate their potential to enhance energy and edible oil security. This study developed a comprehensive framework for evaluating the potential for rapeseed growing in winter fallow fields, factoring in both the suitability of rapeseed growth and the growing season conflicts. First, we used generalized linear regression (GLR) to calculate the precise sowing and harvest dates for both rapeseed and rice, identifying potential growing season conflicts. Second, we employed the MaxEnt model to predict the rapeseed growing suitability. Third, by combining season conflicts and MaxEnt-based suitability, we extracted theoretical potential area and actual potential area for rapeseed growing. Fourth, we conducted a thorough analysis of the limiting factors and explored possible measures for expanding rapeseed growing. The results revealed that the total theoretical potential area for rapeseed growing is approximately 231,910 km². Of this, the total actual potential area is 128,544 km², covering 37.34% of the total YRB’s cropland. Spatially, the greater actual potential area is concentrated in the northeastern YRB, including Jiangsu, Hubei, Anhui, Henan Province, and Qujing in Yunnan Province. Furthermore, in southeastern double-cropped rice regions, there are promising measures (such as early-maturing rapeseed varieties and transplanting methods) to expand rapeseed by mitigating season conflicts, with increased theoretical potential area of approximately 47,302 km². Overall, the YRB demonstrates substantial potential for winter fallow field development for expanding rapeseed growing. These findings could provide science-informed insights for optimizing the utilization of winter fallow fields and contribute to national energy and edible oil security.