Comparison of Banana and Maize Straw Matter Loss and Phosphorus Release by Phosphate-Solubilizing Fungi

Crop straw is an abundant agricultural waste resource, but its lignocellulosic structure limits reuse. The fungus Aspergillus niger (ANG) can promote straw degradation and phosphorus (P) release. However, its degradation efficiency across different crop straws remains unclear. This study compared the straw matter loss and P release of banana leaves (BL), banana stems (BS), and maize straw (MS) by ANG via biomechanical and biochemical pathways. After 7 days of incubation, ANG significantly enhanced the straw dry matter loss of banana stems (41.06%) and maize straw (41.79%), achieving 2.6- and 1.1-fold higher rates compared to treatments without ANG. BL showed a lower straw dry matter loss (20.54%) but had the highest P content of ~3 mg/L among BS and MS. Oxalic acid was the primary organic acid secreted by ANG, achieving the highest value of ~1078 mg/L in the ANG+BS treatment. Meanwhile, these three straws also induced different degrading enzyme activities in ANG. BL stimulated β-glucosidase and lignin peroxidase, whereas BS promoted β-1,4-glucanase in ANG. Overall, ANG is more efficient in BS and MS degradation. Our findings indicate that ANG holds significant potential for straw degradation and the development of specialized fungal inoculants.