Bio-Organic Fertilizers and Microbial Biostimulants in Maize–Cereal Cropping Systems

Sustaining maize-cereal production under intensive agricultural systems is becoming increasingly challenging because of declining soil quality, low nutrient-use efficiency, and escalating abiotic and biotic stresses. In many regions, long-term rice-wheat cultivation has intensified these constraints, prompting greater interest in diversified production systems such as maize-wheat rotations. Within this context, bio-organic fertilizers (BOF) and microbial biostimulants are increasingly recognized not merely as nutrient inputs but as biologically active regulators of plant-soil interactions. This review synthesizes current knowledge on the role of BOF in maize-cereal production systems, with particular emphasis on maize-wheat rotations. It examines their effects on crop productivity, soil health, nutrient dynamics, and resilience to abiotic and biotic stresses. Current evidence indicates that BOF and microbial biostimulants improve crop performance through interconnected mechanisms, including nutrient mobilization, root development, rhizosphere regulation, and microbial-mediated soil processes. Collectively, these mechanisms enhance nutrient-use efficiency, strengthen stress tolerance, and contribute to more stable crop yields. Importantly, the benefits of BOF extend beyond single growing seasons by promoting soil biological activity, nutrient availability, and system resilience across successive crop cycles. Overall, BOF should be regarded not simply as alternatives to mineral fertilizers but as multifunctional regulators of plant-soil processes that support the sustainability of maize-wheat and other cereal-based cropping systems.