Predicting potential cultivation region and paddy area for ratoon rice production in China using Maxent model

Ratoon rice (RR), the practice of obtaining a second crop from the stubble of harvested crop, is more resource efficient, economic-sound, and environmentally-sustainable than single-season rice (SR) and double-season rice (DR). Furthermore, RR can increase rice production where thermal energy is more than that required for SR but not enough for DR. However, the potential cultivation region and paddy area suitable for RR in China remains unknown. In this study, the Maxent model was used to estimate potential cultivation region and paddy area suitable for RR and DR, and their difference was the potential cultivation region and paddy area suitable only for RR. Results indicated that the suitability of RR was primarily influenced by the mean temperature of the warmest quarter, annual precipitation, >10 ℃ accumulated temperature, annual sunlight hours, and altitude. The northern boundary of RR potential cultivation region was northern Jiangsu, Anhui, and Hubei, southern Henan, and northeastern Sichuan. The total potential paddy area suitable for RR in China was 18.69 million hectares (Mha), which included 13.05 Mha suitable for DR and 5.64 Mha suitable only for RR. Out of the total potential paddy area for RR, 28.9% (5.41 Mha), 5.8% (1.08 Mha), and 65.3% (12.20 Mha) were currently planted with DR, RR, and SR, respectively. These results suggest that a total of 13.28 Mha can be planted with RR without the reduction of current planting area of DR. Thus, there is enormous potential to expand the planting area of RR for increasing rice production in China.