Global meta-analysis shows that agronomic interventions enhance nitrogen use efficiency in maize

Low nitrogen use efficiency (NUE) remains a major constraint to global maize ( Zea mays L.) productivity and environmental sustainability, despite substantial nitrogen (N) inputs. To address this challenge, a global meta-analysis of 97 research papers published between 2000 and 2025 was conducted to determine the effects of agronomic management practices on maize NUE, viz ., agronomic N use efficiency (ANUE), apparent N recovery efficiency (ANRE), and partial factor productivity (PFP). Agronomic practices were categorised into four primary groups (fertiliser management, soil amendments, cropping systems, and decision-support systems), with sub-groups, viz ., biochar, deep placement, fertiliser rate, legume intercropping, manure application, nutrient expert systems, residue retention, slow-release fertilizers, and split fertilizer application. Effect sizes were calculated as log response ratios (lnRR) using a multi-level random-effects model. Results revealed that both primary and sub-class agronomic interventions significantly enhanced maize ANUE, ANRE, and PFP. Among primary practices, cropping systems (effect size = 0.43, 0.31 and 0.29) and decision-support systems (effect size = 0.31, 0.26 and 0.17) and showed the highest improvements in ANUE, ANRE and PFP, respectively. Under the sub-group, the greatest improvements were achieved with deep placement (effect size = 0.48, 0.40) on ANUE and ANRE, whereas with legume intercropping on PFP (effect size = 0.26). In contrast, fertiliser applications exceeding recommended rates decreased overall NUEs. Furthermore, the agronomic interventions improved maize ANUE, ANRE, and PFP by 14.67%, 17.98%, and 4.78%, respectively, compared to the control. Tests for publication bias confirmed the reliability of the overall effects. Hence, optimising nitrogen management through precise placement, legume integration, organic amendments, and decision-support tools can enhance maize NUE and sustainability while reducing N losses.