Mapping the potential northern limits and promotion extent of ratoon rice in China

Abstract

Ratoon rice has emerged as a promising rice cropping system to improve grain production and reduce labor costs compared with traditional single/double rice in China. However, the potential planting areas of ratoon rice in China remain unclear. This research investigated the potential northern limits and promotion extent of ratoon rice in China by considering its climatic suitability based on the optimized maximum entropy (MaxEnt) model as well as terrain and land use conditions. The MaxEnt model derived by all environmental variables yielded a good performance, with average AUC (area under the curve) and TSS (true skill statistic) over the validation dataset of 0.940 and 0.825, respectively. The comparison with field samples and previous studies revealed the reliability of the derived potential promotion areas. Potential northern limits contained a closed curve surrounding the Sichuan Basin, and the other curve ran from Yunnan Province to Jiangsu Province. Safe promotion areas of ratoon rice in China were 472,003 km2, mainly located in Sichuan, Hubei, Guangxi and Hunan. Risky promotion areas were 74,150 km2, which were dominant in Henan, Anhui and Yunnan. Our study provides crucial information for rice planting pattern adjustment to alleviate national food insecurity caused by the loss of double rice.