Composting is widely recognised as a sustainable method for converting organic residues into valuable soil amendments. However, residues from coniferous forests pose a distinct challenge due to their high lignin and resin content which slows natural biodegradation. This experimental study aimed to develop an enhanced composting technology for producing a nutrient substrate suitable for coniferous-forest seedlings. Laboratory trials compared a classical aerobic composting process with a microbial-inoculated enhanced process under controlled conditions. Temperature, moisture, pH and C:N ratio were systematically monitored. The enhanced process significantly reduced the composting time by several weeks, lowered the C:N ratio from 35.8 to 15.0, and resulted in compost exhibiting higher nitrogen and phosphorus content, improved humification and slow-release nutrient properties. These findings demonstrate that microbial inoculation effectively promotes the decomposition of lignin-rich forest residues and produces a high-quality organic fertilizer for forestry applications.