Impact of charcoal production on soil micronutrients, enzyme activities, microbial composition, and biomass phosphorus in a derived savannah ecosystem of Nigeria

Soil functions as the active force managing diverse biogeochemical processes in tropical forest ecosystems, including storing and recycling nutrients and decomposing organic matter. Anthropogenic activities, mainly deforestation on charcoal production, have substantially disrupted these processes, leading to notable changes in microbial activities, enzyme functions, and the availability and soil nutrient status of the derived savannah in southwestern Nigeria. While there is increasing recognition of charcoal's impact on soil properties, there remains a noticeable research gap in understanding its specific effects on some associated soil microbial properties, soil enzymes, and micronutrients in charcoal production sites. Our investigation assesses soil nutrition, microbial composition, and some selected associated P and S enzymes under charcoal production sites of derived Savanna, Nigeria. Soil samples were systematically collected at 0-15 cm, 15-30 cm, and 30-45 cm in locations associated with charcoal production (CPS) and non-production sites (NPS). The objective was to assess the microbial biomass content in phosphorus and activity levels of microorganisms in soil, focusing on their production of phosphorus and sulfur enzymes, and to examine the overall nutrient release in these diverse environments. The findings revealed Biomass phosphorus (B_p), Phosphatase (Pho), Thiosulfate dehydrogenase (Tsd), Dimethyl sulfoxide reductase (Dsr), and micronutrients (Mn, Zn, Cu, Co, Fe) were significantly higher in CPS than in NPS. Phytase (Phy) followed a consistent trend at both sites with significant differences among means. Except for copper (Cu), the cobalt (Co), iron (Fe), manganese (Mn), and zinc (Zn) concentrations declined as the soil depth increased in the CPS and NPS across the three locations. This indicates that charcoal production sites in the derived savannah forest of southwestern Nigeria significantly impact soil properties and microbial activities. The higher Bp, Pho, Tsd, and Dsr levels in CPS suggest increased microbial activity and nutrient availability compared to NPS. Additionally, the variation in micronutrient concentrations with soil depth indicates differences in nutrient distribution and availability between the two sites. These findings underscore the importance of further ecosystems to understand the effects of charcoal production on soil ecosystems and to fully develop sustainable management practices that mitigate these impacts.