Optimizing cyanobacterial pellet formulations to enhance dryland restoration

Abstract

Abstract Introduction Biocrusts, complex communities of microorganisms closely associated with soil, are essential components of drylands, supporting soil stability, water availability, and nutrient cycling. Inoculation with biocrust‐forming cyanobacteria has emerged as a promising nature‐based solution to restore degraded drylands, but large‐scale application is often constrained by challenges in production, storage, transport, and soil establishment. Objectives To address these limitations, this study explored the innovative approach of pelletizing biocrust‐forming cyanobacteria with organic amendments (paper residues, biochar, and vermicompost) to enhance inoculum delivery and performance in drylands. Methods Pellets were evaluated for physical stability, cyanobacterial viability during storage, and capacity to facilitate inoculum transfer and colonization of degraded soils. Results Paper‐based amendments showed the greatest structural integrity across the three aggregate‐stability assays, with stable fractions approximately nine‐fold higher than in unamended pellets. These formulations created a favorable microenvironment that led to increases in chlorophyll a of up to 89.4 ± 2.7% during mid‐term storage, but did not result in effective soil colonization. In contrast, biochar‐vermicompost pellets facilitated cyanobacterial release, with chlorophyll a concentrations in the underlying soil approximately 16‐fold higher than in the control. The nutrient‐rich composition of vermicompost, combined with the coarse particle size of biochar, likely enhanced inoculum transfer, particularly at lower amendment concentrations. Conclusion These findings highlight the importance of tailoring pellet formulations to balance physical stability with efficient inoculum release, providing practical insights for cyanobacteria‐based dryland restoration strategies.