Humic substances: their role in improving plant growth and resilience in sustainable agriculture

Background: Many concerns have been raised about the extensive use of agrochemicals and their impacts on environment and soil. Some serious issues include increased soil salinization, toxicity and decrease in soil microbial biodiversity. Biostimulants have emerged as a promising ecofriendly alternative to agrochemicals. Humic substances (HSs) are biostimulants with many beneficial effects in plants physiology and productivity. Aims: This review aims to synthesize current evidence on the role of HSs in supporting sustainable agriculture that improves crop productivity while maintaining good soil health in changing environmental conditions. Methods: Relevant studies related to HSs and their effects on soil fertility, plant growth, stress tolerance and hormonal regulation were collected from major scientific databases including Scopus, Web of Science, and Google Scholar. The main outcomes of these studies were extracted and analyzed to provide an overview of the available evidence. Results: The literature shows that the integration of HSs into agricultural practices improves soil structure, increases water retention, maintains healthy microbial diversity and enhances plant productivity. Conclusions: This review highlights the importance of using HSs in enhancing soil health and plant physiology. However, further studies are required to integrating new technologies and diversify HSs sources, plants species, and different environments.