Navigating the synergy between environmental efficiency and productivity in China's land operation scale expansion

Balancing productivity growth with emissions reduction is a central challenge for sustainable agriculture. Using over 390,000 household-year observations from 1993 to 2020, this study examines how land operation scale affects greenhouse gas emission intensity (GEI) and unit production value in China, with lower GEI indicating higher environmental efficiency and unit production value capturing economic productivity per unit planting area. We find U-shaped relationships between land operation scale and both outcomes. The turning point of unit production value occurs earlier than that of GEI, creating a “synergy window” in which moderate scale expansion can reduce emission intensity while improving unit production value. This window is not universal across the nine agricultural zones, reflecting regional differences in production systems and scale-response patterns. Mechanism decomposition identifies fertilization intensity as the dominant pathway, with additional contributions from mechanical input intensity and planting structure. Multi-scenario simulations to 2035 suggest that moving toward the estimated turning-point scale can substantially reduce GEI, while the recovery of unit production value depends on addressing land-transfer and fragmentation constraints. These findings provide new evidence for land policies that coordinate productivity growth and low-carbon agricultural transition.