Fig. 3: Socioeconomic benefits, environmental benefits and potential planting regions of PR.

a, Costs in the first and subsequent seasons, labour, outputs (gross income from grain sales) and net profits from AR and PR production. For AR, seed, ploughing, seedling nurseries, transplanting, crop management and harvest are needed in every season. For PR, these are all needed in the first season; however, in the subsequent seasons, tillers of the plant are accomplished by regrowth, and thus seed, seedling nurseries, ploughing and transplanting are not needed, resulting in considerable savings of money and labour. US$1 = CN¥6.4 as of 4 November 2021. The data were derived from Experiment 3, with LSD for labour costs of US$203; non-labour costs, US$203; labour number, 7 days; and economic profit, US$838 (P < 0.05) (Supplementary Table 8 and Extended Data Fig. 7). b, Soil benefits of perennial rice cropping system. Data are presented for averaged soil pH, total plant-available soil-water capacity (%), soil organic carbon (SOC) accumulation (Mg ha⁻¹) and total nitrogen (TN) (Mg ha⁻¹) accumulation, which have LSDs (P < 0.05) of 0.27 units, 1.7%, 1.1 Mg ha⁻¹ and 0.2 Mg ha⁻¹, respectively. The error bars represent the standard error of each treatment. The soil properties refer to the 0–40 cm soil layer. PR-2y, PR-3y and PR-4y are perennial rice in years 2, 3 and 4, respectively. Data are from Experiment 3 (Supplementary Table 9 and Extended Data Fig. 8). c, Optimal ecological zoning of PR. Data derived from 25,049 meteorology stations, 2015–2020, obtained from the National Centers for Environmental Information (https://ncei.noaa.gov). On the basis of our findings from Experiment 5 (Supplementary Table 10 and 11 and Extended Data Fig. 9), we selected the regions suitable for planting PR, in which the average monthly temperature was higher than 13.5 °C (contours) and in which average daily temperatures lower than 4 °C lasted for fewer than five days (green dots within the contours; 2,695 stations).

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