Quantification of Microbial Biomass Carbon and Nitrogen in Leaf Litter Amended Soil in Northern Nigeria

A 119-day laboratory incubation study was conducted to evaluate microbial biomass dynamics in soil amended with different leaf litters. The treatments included five leaf litter sources: African mahogany (Khaya senegalensis), Mango (Mangifera indica), Beechwood (Gmelina arborea), Red River Gum (Eucalyptus camaldulensis), and a mixed litter treatment, arranged in a Completely Randomized Design with three replicates. Chemical properties of the leaf litters, including organic carbon, nitrogen, sulfur, potassium, calcium, sodium, magnesium, total soluble polyphenols, and lignin content, were analyzed. Soil microbial biomass carbon (SMBC) and nitrogen (SMBN) were determined using the chloroform fumigation incubation (FI) method.

Among the treatments, Eucalyptus camaldulensis exhibited the highest C:N ratio (33.3), while Gmelina arborea showed the lowest (20.6). Significant differences (p<0.05) were observed across leaf litter types and weeks for soil microbial carbon and nitrogen parameters. Soil amended with Eucalyptus camaldulensis recorded the highest microbial biomass carbon (122.85 mg kg⁻¹), significantly (p<0.05) exceeding the values for mixed leaf litter, control, Gmelina arborea, Khaya senegalensis, and Mangifera indica.

The highest microbial biomass nitrogen values were observed in soils amended with Khaya senegalensis (13.90 mg kg⁻¹) and Mangifera indica (13.25 mg kg⁻¹), with the control treatment yielding the lowest value. Eucalyptus camaldulensis amended soil also had the highest microbial biomass C:N ratio, followed by Mangifera indica, Gmelina arborea, the mixed treatment, and the control. The results suggest that Mangifera indica, Khaya senegalensis, and the mixed leaf litter have a greater potential to enhance soil microbial nitrogen, while Eucalyptus camaldulensis promotes higher carbon activity in the soil