Enhancing Cocoa Pod Husk Decomposition Through a Microbial Consortium of Trichoderma harzianum, Pleurotus ostreatus and Mikrobat

Cocoa (Theobroma cacao L.) is a major global commodity, with Indonesia ranking among the top producers. However, cocoa pod husks which account for about 73% of the fruit mass-remain largely underutilized, creating significant agricultural waste and environmental concerns. These husks are rich in nutrients and lignocellulosic compounds, making them suitable for conversion into compost. This study aimed to evaluate the effectiveness of Trichoderma harzianum, Pleurotus ostreatus and a microbial consortium (Mikrobat) as bio-decomposers for enhancing the composting of cocoa pod husks and to assess their impact on compost physicochemical quality and lignocellulose degradation.

The experiment was conducted using a randomized block design with seven treatments (single and combined inoculations) and three replications, resulting in 63 experimental units. Composting parameters observed included temperature dynamics, mycelial growth, color, texture, odor, weight loss, nutrient content (C-organic, N, P, K) and lignocellulolytic composition (NDF, ADF, cellulose, hemicellulose, lignin).

The results showed that microbial treatments significantly accelerated the composting process, as indicated by elevated early- phase temperatures, rapid mycelial colonization and improved physical maturity (darker color, finer texture). The combination of T. harzianum and Mikrobat yielded the highest C-organic (17.90%), total N (1.01%) and K (0.82%) contents with an optimal C/N ratio (~18), while the triple combination produced the highest P (1.08%). Lignocellulolytic analysis revealed that T. harzianum + P. ostreatus effectively reduced fiber and lignin contents, whereas T. harzianum + Mikrobat promoted the transformation of lignin into stable humic compounds.