Magnesium fertilization enhances yield and biomass carbon sequestration in global cropping systems: A meta-analysis with field validation in sugar beet

Ensuring food security while enhancing agricultural carbon sinks is a central challenge under global climate change. Magnesium is emerging as a key regulator in intensive cropping systems and acidic soils, yet a comprehensive framework linking photosynthetic performance to biomass carbon allocation at the field scale remains lacking. To elucidate the synergistic enhancement of crop production and carbon sequestration capacity by magnesium fertilizer, we integrated a global meta-analysis of 2487 paired observations (1964–2025) with three-year field experiments across six locations in China using sugar beet ( Beta vulgaris L.) as a model root crop. The meta-analysis showed that magnesium application increased crop plants yield by an average of 22.45% globally, with substantial improvements in net photosynthetic rate ( Pn , +32.16%) and photosystem photosynthetic performance index (PI ABS , +44.50%). Magnesium application altered carbon allocation patterns, increasing the root-to-shoot ratio (R/S) and biomass carbon storage (BCS) by 20.84%. To verify these global patterns, multi‑site field validation experiments showed that magnesium application (50–100 kg ha −1 ) persistently improved root yield and BCS of sugar beet across sites. The optimum rate of 80 kg magnesium ha −1 increased BCS by 34.32% relative to low‑magnesium conventional management, whereas excessive magnesium (>100 kg ha −1 ) weakened these benefits. We propose a mechanistic framework of “photosystem activity—carbon assimilation—carbon allocation” driven by magnesium nutrition. Our findings suggest that site‑specific magnesium management within the range of 50–100 kg ha −1 may serve as a promising agronomic strategy for synergistically improving field crops productivity and agronomic carbon sequestration potential, providing important insights for sustainable crop production.