Effects of biostimulants and biofertilizers on crop yield and agroecosystem sustainability

Abstract

Global food production systems face mounting pressures from population growth, climate change, soil degradation, and the environmental costs of intensive agrochemical use. Biostimulants and biofertilizers are increasingly evaluated as complements to conventional inputs because they can improve plant nutrition, stress tolerance, and soil biological functioning. This systematic review and meta-analysis aimed to (1) quantify reported effects on crop yield; (2) examine moderators including product category, application method, crop type, climate, and soil conditions; (3) synthesize evidence on agroecosystem sustainability; and (4) assess the evidence base using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) 2020 framework. Searches of Web of Science, Scopus, PubMed/MEDLINE, and Google Scholar covered January 2000 to December 2024. Following screening, 274 primary studies were retained for the evidence synthesis. Quantitative results were summarized as log response ratios (lnRR) and back-transformed percentage changes, with estimates for non-microbial biostimulants and microbial biofertilizers reported separately because the two evidence streams differed in study composition and moderator structure. Non-microbial biostimulants increased crop yield by 17.9% (95% CI [confidence interval]: 16.2–19.7%; lnRR = 0.165), with the largest reported response for soil application (+28.8%; 95% CI: 24.0–33.6%). Biofertilizers increased yield by 16.2% (95% CI: 15.2–17.2%; lnRR = 0.150), with stronger responses in dry climates (+20.0%; 95% CI: 18.3–21.7%). Vegetable crops showed the strongest response to non-microbial biostimulants, whereas legumes tended to respond strongly to biofertilizer inoculation. Because between-study heterogeneity was substantial, these averages are considered as context-dependent rather than universal effects. Thus, the evidence supports biostimulants and biofertilizers as potentially useful complements to synthetic inputs, particularly under abiotic stress or nutrient limitation, while highlighting the need for standardized formulations, transparent statistical reporting, long-term field validation, and context-specific application protocols.