Abstract

Although soil microbial biomass (MBC) comprises less than 5% of soil organic matter, it responds rapidly to changes in soil management practices and, therefore, is generally used as an early indicators of changes in soil carbon. The objective of this study was to evaluate the effects of tillage practices (conventional tillage and no-tillage) and fertilizer types (synthetic, organic, and no fertilizer) on soil MBC. The field experiment, located in Buea, was arranged in a split-plot design with three replications and had tillage systems as main plots and fertilizer types as sub-plots. Soil samples were collected at 0–15 cm depth at an interval of 4 (early season), 8 (mid-season) and 12 (late season) weeks during the 2020 and 2021 minor and major growing seasons respectively, for the determination of soil MBC by the chloroform fumigation and extraction method. The findings of the study showed that the main effect of tillage practice and fertilizer types was nonsignificant (p>0.05) in the 2020 and 2021 study season throughout the sampling period. Plots under zero tillage with control experiments (No.Till:CON) recorded the highest soil MBC in the 2020 season (201 mg/kg) while in the 2021 season, plots under zero tillage with organic fertilization (No.Till:ORG) recorded the highest (400.4 mg/kg) soil MBC. Soil MBC was higher in the 2021 season than in the 2020 season. These findings suggest that the use of compost in combination with either conventional tillage or no-tillage in farms in the study area could potentially enhance soil MBC.

Key words: Tillage, fertilizer type, microbial biomass carbon, carbon sequestration.