Variable-rate bio-based nitrogen fertilization in grain maize: field evaluations in Belgium
摘要
Empirical field-scale evidence for site-specific management of bio-based fertilizer (BBF) application is largely missing. Hence, implementing BBFs in this manner on commercial maize farms in this study delivers rare applied insight into agronomic, economic, and environmental performance under real farming conditions. Recent EU Soil Monitoring Law (2025) and the RENURE approval in EU (2025) formalize soil-health restoration and circular nitrogen (N) use as defined regulatory priorities, situating precision variable-rate (VR) bio-based fertilizer (VR-BBF) application within an emerging compliance-oriented nutrient management framework. Three commercial fields (2.7–6 ha) in East Flanders received uniform-rate RENURE ammonium sulphate as a bio-based alternative (UR-BBF) and variable-rate bio-based fertilization. In two fields, these treatments were benchmarked against uniform-rate synthetic fertilizer (UR-S) to reflect standard practice. All VR treatments were informed by on-line soil sensing, crop sensing, and farmers field-knowledge. Comparing VR treatments against UR-BBF and UR-S, the results demonstrated that VR efficacy is site-specific. In Aalter (6 ha) and Beervelde (3 ha), VR-BBF application outperformed uniform practices, delivering fresh matter (FM) yield gains of 2.72–4.06 t ha−1 and increasing gross margins by 356–465 EUR ha−1. Conversely, the Lemberge field (2.5 ha) exhibited FM yield and profit losses, attributed to a non-N limiting constraint. These findings indicate that while VR-BBF application can be a promising pathway for integrating circular nutrient production outputs via precision agriculture to ensure better nutrient allocation, nevertheless, its practical success depends on strategies that are strictly linked to local soil properties and capable of addressing non-N limiting constraints to prevent economic and environmental trade-offs.