Evaluation of The Synergy between Cyanobacteria and Bentonite on the Stabilization of Soils Susceptible to Wind Erosion

Document Type : Research Paper

Authors

• RAMIN GHAHREMANPOOR ¹
• MANOUCHEHR GORJI ²
• AHMAD ALI POURBABAEE ²
• MOHAMMADTAGHI TIRGARSOLTANI ²

¹ Department of soil Science, Faculty of Agriculture, University of Tehran, Karaj, Iran.

² Department of soil Science, Faculty of Agriculture, University of Tehran, Karaj, Iran

Abstract

Keywords

• bentonite
• bio-mineral stabilization
• cyanobacteria
• wind erosion
• dust control

Main Subjects

• soil erosion and conservation

Introduction

Wind erosion is a major driver of land degradation in arid and semi-arid regions, where low rainfall, sparse vegetation, and fragile soil surfaces create conditions highly susceptible to particle detachment and transport. Conventional soil stabilizers—especially chemical mulches—have shown limited success due to their high cost, short longevity, and incompatibility with natural ecosystems. As a nature-based alternative, cyanobacteria-induced biostabilization has emerged as a promising approach; cyanobacteria enhance soil cohesion through the production of extracellular polysaccharides (EPS), nitrogen fixation, and formation of biological crusts. Meanwhile, bentonite clay, owing to its swelling capacity, high surface charge, and water retention, can improve physical soil cohesion and reduce detachability. Despite these advantages, interactions between biological (cyanobacteria) and mineral (bentonite) stabilizers remain poorly understood, and few studies have evaluated their combined effectiveness against wind erosion. This study aims to assess the synergistic potential of cyanobacteria–bentonite bio-mineral stabilization in enhancing soil structural stability and increasing threshold friction velocity under controlled wind tunnel conditions.

Methodology

Surface soil samples (0–5 cm) were collected from wind-erosion-prone lands of Aran-Bidgol (Kashan). After air-drying and sieving (<2 mm), initial physico-chemical properties including texture, pH, EC, organic carbon, and macronutrients were measured. Cyanobacterial strains (79et, 50et, 57et, and a mixed combination) were obtained from the National Biological Resource Center and cultured in BG-11 medium. Bentonite was prepared from a natural calcium-rich source. A factorial experiment was implemented in a randomized complete block design (RCBD) with four replicates and the following treatments:

(1) cyanobacteria strains, (2) bentonite at 25 and 50 g m⁻², (3) cyanobacteria + bentonite combinations, and (4) untreated control. Treatments were applied to 60 soil trays (100 × 30 × 3 cm) in six rounds at three-week intervals. Cyanobacteria suspension (0.5 g L⁻¹) and bentonite slurry were sprayed uniformly. Trays were maintained utdoors under controlled conditions for six months. Measured variables included:

wind erosion threshold velocity, using a laboratory wind tunnel;

mean weight diameter (MWD) of aggregates via dry sieving;

penetration resistance using a micro-penetrometer;

chlorophyll a, microbial respiration, microbial biomass carbon, organic C, and total N. Data were analyzed using ANOVA and Tukey’s test at 5% significance level.

Results and Discussion

The soil was sandy loam with low organic carbon (0.17%) and moderate salinity (EC = 8.8 dS m⁻¹), typical of erosion-prone arid-region soils. ANOVA indicated that cyanobacteria and bentonite independently and significantly increased wind-erosion resistance, MWD, and penetration resistance (p < 0.01). Cyanobacteria significantly increased biological indicators (chlorophyll a, microbial biomass, respiration), whereas bentonite showed no significant effect on biochemical properties. Wind-tunnel tests revealed a substantial rise in threshold friction velocity in all cyanobacteria-treated soils due to EPS-induced aggregation and crust formation. Bentonite also increased threshold velocity by filling pore spaces and promoting cohesive bonding among particles. The highest erosion resistance occurred in the combined treatment of mixed cyanobacteria + bentonite (50 g m⁻²), emonstrating a strong bio-mineral synergistic effect. Similarly, MWD increased markedly in both cyanobacteria and bentonite treatments, and reached its maximum under the combined application. These results indicate that physical bonding by bentonite creates a conducive matrix for microbial colonization and EPS network formation. Cyanobacteria significantly increased soil organic carbon, microbial biomass, and total nitrogen, confirming the biological enrichment of treated surfaces. Bentonite alone did not alter chemical properties but strengthened structural integrity. Overall, the integration of biological crust formation and mineral-based cohesion provided a robust framework for stabilizing sandy loam soils against wind detachment.

Conclusions

The combined application of cyanobacteria and bentonite significantly enhanced soil resistance to wind erosion through complementary biological and mineral processes. While cyanobacteria improved biochemical activity and aggregate stability via EPS production and biomass accumulation, bentonite reinforced physical cohesion and reduced particle mobility. The bio-mineral stabilization strategy demonstrated superior performance compared with individual treatments, particularly in increasing wind-erosion threshold velocity and aggregate stability.
These findings highlight the potential of low-cost, eco-friendly, and durable stabilizers for managing wind erosion in dryland environments. The approach offers a practical alternative to conventional chemical mulches and can contribute to sustainable land-degradation mitigation in arid landscapes.

Funding

This research was conducted with the financial and moral support of the Vice Chancellor for Research, University of Tehran.

Authorship contribution

First author: Student: preparation of samples, conducting experiments and collecting data, performing calculations, statistical analysis of data, analyzing and interpreting information and results, preparing the article draft

Second author: Thesis supervisor, research design, supervising the research stages, reviewing and controlling the results, revising and finalizing the article

Third author: Thesis advisor, participating in research design, supervising the research, reading and revising the article

Fourth author: Thesis advisor, participating in research design, supervising the research, reading and revising the article.

Data availability statement

The data of this study are available upon request from the authors.

Acknowledgements

We would like to thank the Honorable Vice Chancellor for Research, University of Tehran / Faculty of Agriculture, for their financial support/cooperation in carrying out this study.

We would like to thank the honorable referees for providing structural and scientific comments.

Ethical considerations

The authors have observed ethical principles in conducting and publishing this scientific study, and this is confirmed by all of them.

Conflict of Interest

There is no conflict of interest in this article regarding the authors.