Zinc (Zn) is crucial for both plant metabolism and human nutrition, with its deficiency being a global health concern. Strategies to increase its availability in food, such as agronomic biofortification, have gained prominence. This study evaluated the impact of foliar spraying of Zn [at full bloom stage: 0 (control) and 600 g ha⁻¹, as ZnSO₄⋅7H₂O] on the nutritional quality of cowpea (Vigna unguiculata L. Walp.) grains. Field experiments involving 20 cowpea genotypes were carried out over two seasons in a Typic Quartzipsamment under a no-tillage system. The photosynthetic responses of cowpea plants and the concentrations of Zn, amino acids, sucrose, total sugars, and storage proteins (glutelin, albumin, prolamin, and globulin) in grains were analyzed. All genotypes showed enrichment of Zn in grains in response to ZnSO₄⋅7H₂O application compared to untreated plants. Foliar spraying of ZnSO₄⋅7H₂O during initial grain filling was ideal for increasing Zn concentration in grains and improving plant physiological processes. Additionally, Zn fertilization led to higher concentrations of storage and total amino acids and proteins in the grains, supporting the rational application of Zn in cowpea production to improve the nutritional quality of grains and increase plant productivity.

Iron deficiency is a widespread public health concern, particularly in regions where rice (Oryza sativa) and beans (Phaseolus spp.) are staple foods with naturally low bioavailable iron content. Agronomic biofortification is a practical strategy to increase micronutrient levels in crops through soil, foliar, and seed-based fertilization techniques. This review synthesizes scientific studies published between 2014 and 2024 that evaluated the effectiveness of agronomic iron biofortification methods in rice and beans. The results demonstrate that site-specific interventions, such as the selection of iron sources and application methods, can improve iron concentration in grains and contribute to more nutritious and resilient food systems. However, challenges remain. There is limited information about human iron bioavailability, and the response to fertilization varies depending on soil and environmental conditions. To address these gaps, future research should include bioavailability assessments and field validation. Even so, integrating iron biofortification into standard fertilization practices is a promising approach to improve food quality and combat hidden hunger in vulnerable populations.

Purpose Potassium (K) is essential for plant growth, yet most Brazilian soils are K-deficient, increasing reliance on imported mineral fertilizers. Organomineral fertilizers (OMF) combine organic residues with mineral nutrients and are a potential solution to reduce environmental impacts and improve K use efficiency. In this study we evaluated the release of K from OMF and its influence on the chemical, physical, and microbiological properties of a sandy loam soil. Methods A soil incubation study was conducted using columns filled with sandy loam soil treated with OMF and potassium chloride (KCl) for comparison. Miscible displacement tests were performed to assess K leaching, and basal soil respiration was measured to estimate microbial activity. Results OMF showed a slower and more gradual release of K over time compared to KCl. This slow release contributed to prolonged K availability and greater nutrient retention in the soil, delaying leaching losses. In addition, OMF increased microbial activity, indicating improved biological conditions in the soil. Conclusions OMF improve K retention and enhance microbial activity in sandy soils, demonstrating their potential to increase K use efficiency and reduce fertilizer losses. This study highlights K dynamics under miscible displacement conditions, integrating chemical, physical, and biological assessments rarely addressed together in previous research. Our results support the use of OMF as a sustainable strategy, aligned with the United Nations Sustainable Development Goals, especially in regions with low natural K reserves.