Controlled-release fertilization reshapes maize yield through plant-soil synchrony: shifting from nitrogen supply intensity to synchronization-driven vegetative remobilization

Background and aims: Nitrogen (N) management in maize systems is constrained by low fertilizer use efficiency and substantial environmental losses, particularly in arid irrigated regions where soil N heterogeneity disrupts plant uptake and allocation. Controlled-release fertilizers (CRFs) offer a promising approach to coordinate soil N supply with crop N demand and regulate internal N cycling during yield. Methods: To elucidate the mechanisms by which CRF enhances N utilization and coordinates N allocation, field experiments were conducted in western Inner Mongolia, China from 2022 to 2024. This study to evaluate their impact on N accumulation (NA), tissue-specific N partitioning and N remobilization, leaf N remobilization efficiency (NREleaf), stem N remobilization efficiency (NREstem), supply-demand synchrony index (SDI), supply-plant N requirement synchronization (SPNR), soil nitrate dynamics, and maize yield throughout the growing season. Results: The results showed CRF markedly enhanced N remobilization, with NREleaf and NREstem increasing by 12.3% and 24.8%. Notably, CRFs also improved overall N supply-demand synchronization: average SDI values for CF3 and CF2 were 0.77 and 0.86, compared with 0.61 for regular fertilizer (RF), representing a 26-41% increase. Building on this, structural equation modeling revealed that the mechanism regulating yield shifted from N supply intensity under RF (R-2= 0.74) to synchronization-driven control under CRF (R-2 = 0.79), in which SPNR coordinated N allocation and remobilization (>0.8 contribution) to determine grain NA and final yield. Conclusion: These findings demonstrate that optimizing N supply-demand synchronization, rather than increasing N inputs, fundamentally reshapes maize yield formation by coordinating internal N cycling. CRFs, particularly at moderate N rates, offer a pathway for improving N use efficiency while reducing environmental risk, providing actionable insights for sustainable maize production in N-limited, arid irrigated systems.