Introduction: Wind erosion is one of the major environmental challenges in arid and semi-arid regions of Iran, particularly in desert areas such as Aran and Bidgol and Kashan, where low precipitation, poor vegetation cover, and fragile soils intensify the phenomenon. Mulching is a common method for stabilizing mobile sands; however, petroleum-based mulches are limited due to high costs and adverse environmental impacts. Accordingly, bio-based mulches derived from agricultural and industrial by-products are considered safe, biodegradable, and cost-effective alternatives. The present study aimed to develop an eco-friendly mulch based on zeolite, bentonite, and molasses (a by-product of the sugar industry).
Materials and Methods: The research was conducted at the laboratory scale using a D-Optimal mixture design approach. Sand samples were collected from the deserts of Kashan and characterized according to ASTM standards. The proposed mulch was formulated from calcium bentonite (mesh 200), micronized clinoptilolite zeolite, and concentrated industrial molasses. The mixing ratios were designed and tested using DX11 software. Five performance indices were used to evaluate mulch quality: shear strength (SS), compressive strength (CS), impact resistance (IR), abrasion resistance (AR), and crust thickness (CT). The experimental results were analyzed using ANOVA, Duncan’s test, and Pearson and Spearman correlation analyses. Polynomial models were developed to fit the responses and determine the optimal formulation through mathematical optimization.
Results: ANOVA results showed that mulch treatments had significant effects (p < 0.05) on all performance indices. Maximum shear strength was recorded in treatments 28, 14, and 15, at 8.27, 8.20, and 8.17 N/cm², respectively. The highest compressive strength was observed in treatments 1 and 15, at 3.17 and 3.15 kg/cm², respectively. The greatest impact resistance was found in treatments 15, 28, 33, and 18, with values of 0.75, 0.71, 0.71, and 0.71, respectively. The highest abrasion resistance (value = 1) was recorded across treatments 4, 2, 9, 19, 21, 22, 24, 29, 26, and 30. Maximum crust thickness was obtained in treatments 21, 16, and 30, at 1.92, 1.91, and 1.89 cm, respectively. A strong and significant correlation was found between shear, compressive, and impact strength, while abrasion resistance showed weak and insignificant correlations with the other variables. The optimized mulch formulation aimed at maximizing SS, CS, IR, and CT consisted of 50% molasses, 23% bentonite, and 27% zeolite. Model validation results indicated a good agreement between experimental data and model predictions.
Discussion and Conclusion: Molasses, due to its adhesive properties and ability to bind soil particles, combined with bentonite as a calcium source for improved water retention and zeolite for its high cation exchange capacity, resulted in the development of a sustainable mulch with favorable physical and mechanical properties. Increasing molasses content directly enhanced mechanical strengths and crust thickness. Zeolite was more effective in improving abrasion resistance, whereas bentonite played a key role in impact resistance and crust thickness. The findings are consistent with previous studies. The proposed optimized formulation, due to its accessible raw materials, simple preparation process, non-toxicity, and potential for field application, can serve as an effective alternative to petroleum-based mulches in Iran’s desert regions. However, final performance validation requires field trials under actual climatic conditions. This study serves as a successful example of synergizing natural materials and industrial residues to develop environmentally focused technologies within a circular economy framework.