Global research trends on seaweed-based amendments for soil health and crop productivity

Seaweeds have emerged as pivotal bioresources in sustainable agriculture, bridging the soil–crop–nutrient continuum through their multifaceted roles in enhancing soil fertility, nutrient cycling, and crop productivity. These bioactive compounds-including phytohormones (auxins, cytokinins, gibberellins), polysaccharides (alginates, laminarin, fucoidan, carrageenan), phenolic antioxidants, and betaines-modulate plant physiological processes such as photosynthetic efficiency, nutrient transporter expression, and stress-responsive gene regulation, while simultaneously improving soil organic matter content, cation exchange capacity, and rhizosphere microbial diversity. The study presents an inclusive bibliometric analysis of global research on the impacts of seaweeds and algal products on crop yields, plant growth, and soil nutrient dynamics from 2000 to 2024. Data were retrieved from the SCOPUS database using targeted keyword queries and analysed using the bibliometrix R package and VOSviewer to assess performance metrics, thematic mapping, and collaboration networks. A total of 156 English-language non-redundant journal articles were identified, reflecting an average annual growth rate of 11.94% in scientific output, with a marked increase after 2018 and a peak in 2024. Asia led global contributions (84 publications), followed by Europe (41) and North America (12). Keyword and thematic analyses revealed four dominant research clusters: (1) algal physiology and bioactive mechanisms, (2) seaweed-based inputs for yield and nutrition, (3) soil health and organic amendments, and (4) biofertilizers and stress adaptation strategies. Research trends indicate a thematic shift from foundational algal studies in the early 2000s toward applied agronomic applications and integrated soil health management in recent years. Findings underscore the potential role of seaweed in climate-smart agriculture, the circular bioeconomy, and nature-based soil restoration. However, research gaps remain in field-based validation, standardised application protocols, economic feasibility assessments, and the exploration of underutilised species. This study provides a consolidated evidence-base to inform future research, policy development, and commercial innovation for scaling seaweed-based solutions in sustainable agriculture.