Trade-offs between global warming potential, eco-efficiency and water use efficiency under different establishment...

Rice, a staple food for over half the world's population, is vital for achieving Sustainable Development Goal 2 (Zero Hunger). However, its production poses environmental challenges (SDG 13) due to high global warming potential (GWP), water depletion, and low eco-efficiency. Therefore, study conducted over two years (2022-23 and 2023-24) on sandy clay loam soil of Southern India evaluated trade-offs in yield, GWP, water use efficiency (WUE), carbon efficiency ratio (CER), and eco-efficiency under different establishment methods and nitrogen (N) management strategies. Results revealed that the puddled transplanted method achieved the highest yield (4997 kg ha^-1) but also had the highest GWP, greenhouse gas intensity (GHGI), and water consumption, resulting in the lowest eco-efficiency (0.12 US$ kg^-1 grain). In contrast, direct-seeded rice (DSR) reduced GWP by 50.5 %, GHGI by 47.36 %, while achieving the highest CER (46.7 %), economic WUE (32.13 %), and eco-efficiency, despite an 10 % yield reduction over puddled method. Likewise, applying 100 % recommended nitrogen dose (RDN) with 0.4 % nano urea (N5) increased the grain yield by 7.9 % and eco-efficiency by ~6 % over 100 % RDN alone, reducing N loss by 36.7 %. Therefore, integrated approach; DSR × N5 lowered GWP by 44.5 %, reduced irrigation water use by 47.8 %, and improved eco-efficiency by 44.4 %. While the puddled method slightly boosts yield (~10 %), it comes at a substantial environmental cost. Thus, DSR with 100 % RDN and nano urea emerges as a sustainable strategy to mitigate GWP, conserve water, and enhance environmental quality. This study analyzes the trade-offs between yield and environmental indicators, offering valuable insights for achieving sustainable rice production through optimized establishment methods and nitrogen management.