Microalgae-based biofertilizers: A comprehensive meta-analysis of their effectiveness in agricultural systems

The global agricultural sector faces increasing pressure to enhance productivity while ensuring environmental sustainability. Microalgae-based biofertilizers offer a promising alternative to synthetic fertilizers, leveraging their nutrient-rich profiles and biostimulant properties to improve crop growth, yield, and soil health. This meta-analysis synthesizes findings from 25 studies focusing exclusively on eukaryotic microalgae published over the last 15 years, assessing the effectiveness of microalgae-based biofertilizers across diverse agricultural systems. Using a random-effects model, we observed an average crop performance improvement of 51.75% (∼52%) compared to control treatments (95% CI: [39.15%, 65.48%], p < 0.0001), despite high heterogeneity among studies (I 2 > 90%). Subgroup analyses revealed significant variability influenced by crop type, environmental conditions, and algal species. High-performing crops, such as mung beans ( Vigna radiata ) and tomatoes ( Solanum lycopersicum ), demonstrated yield increases exceeding 60%, while controlled environments yielded more consistent results than field applications. In addition to enhancing plant growth, microalgae significantly improved soil health by increasing microbial activity, enzymatic functions, and nutrient availability. Species like Chlorella vulgaris and Scenedesmus obliquus consistently showed superior efficacy, promoting root elongation, photosynthetic efficiency, and nutrient cycling. Furthermore, microalgae-based biofertilizers demonstrated substantial environmental benefits, including reduced reliance on synthetic fertilizers, carbon sequestration, and enhanced resilience against abiotic stressors. Despite variability in results and challenges related to scalability and production costs, the findings emphasize the potential of microalgae to advance sustainable agricultural practices globally. Future research should focus on standardizing application methods and optimizing formulations to facilitate the broader adoption of microalgae-based biofertilizers in sustainable agricultural systems.