Sequential High-Yielding Cultivar Selection and Nitrogen Optimization Enhance Ratoon Rice Sustainability via Lower Environmental Footprints and Higher Economic Returns

Growing ratoon rice (RR) offers a pathway for enhancing food security; however, the combined contribution of cultivar selection and cultivar-specific nitrogen (N) management on the productivity‒environment nexus remains poorly understood. A five-year field experiment in southeast China was conducted in two sequential phases. The three-year cultivar screening (2019–2021) identified Yongyou 4949 (YY), Hanyou 73 (HY), and Fengliangyouxiang 1 (FLY) as high-yielding cultivars. Under the conventional ratoon-season N rate (175 kg N·ha -1 ) evaluated during 2022–2023, FLY showed superior ratooning performance and N uptake efficiency, together with lower yield-scaled nitrogen and carbon footprints (NF y and CF y ) than YY and HY. Further N-rate evaluation in FLY showed that reducing the ratoon-season N input from 175 (FLY175) to 125 kg N·ha -1 (FLY125) maintained high grain yield, increased the apparent N recovery efficiency by 78%, and reduced reactive N losses by 23%. Compared with FLY175, FLY125 also reduced NF y and CF y by 23% and 18%, respectively, while increasing the net ecosystem economic benefit by 5.7% (or 1.3 × 10 3 CNY·ha -1 ). These improvements were mainly associated with lower ammonia (NH 3 ) volatilization and methane (CH 4 ) emissions. Thus, under the soil, climate, and management conditions of this study, 125 kg N·ha -1 represents a suitable ratoon-season N rate for FLY. Overall, these results support a sequential, cultivar-specific strategy of selecting high-performing cultivars and optimizing their N management. This approach has potential to align farmers’ economic returns with reduced environmental impacts in the Taihu Lake region and other agroecologically similar ratoon rice areas.