Development and evaluation of biodegradable seedling tubes from beeswax and macadamia nut composites

This study investigates the development of biodegradable seedling tubes using macadamia nutshell powder as a filler and beeswax as a natural binder, to provide a sustainable alternative to conventional polyethene tubes. A total of twenty-four experimental runs were conducted following a Design of Experiments framework to evaluate the effects of beeswax–to–macadamia ratios (90:10, 70:30, and 50:50 wt %), soil pH, temperature, and moisture content on biodegradability over a 28-day soil burial test. Elemental composition was determined by X-ray fluorescence analysis, while statistical significance was assessed using analysis of variance. Results showed that biodegradation rates ranged from 28.2% to 58.3%, with the beeswax ratio exerting the most significant influence (p < 0.05) on degradation behaviour, followed by temperature and soil moisture. Tubes with higher beeswax content exhibited greater structural stability and water resistance but lower biodegradability. Conversely, lower beeswax ratios favoured faster microbial decomposition. Elemental analysis revealed appreciable levels of SiO2, Al2O3, and Fe2O3, which contribute to mechanical stability and may facilitate micronutrient enrichment during decomposition. The findings confirm the technical feasibility of producing biodegradable, plantable seedling tubes from locally available agro-wastes. The composite formulation offers an environmentally sound, low-cost alternative to plastic seedling containers while supporting circular-economy principles and promoting sustainable nursery management practices in Malawi and similar contexts.