Differential Impacts of Cropland Expansion on Soil Biological Indicators in Two Ecological Zones

Agricultural expansion in Sub-Saharan Africa is characterized by different farm ages smallholder communities. This study investigated changes microbial indices broadly (i) at the reconnaissance survey level four agro-ecological zones and (ii) farms forest (Dompem) forest–savanna transition (Adansam) zones, as influenced duration of cultivation. Soils from one-year (first cultivation cleared forest/fallow), three-year, five-year, ten-year were analyzed for basic soil properties, active or labile carbon (POXC), basal respiration (BR), biomass (Cmic) using permanganate oxidizable C, alkali trap, chloroform fumigation incubation. In both levels, POXC content was <1% organic (SOC) all higher wet positively correlated with SOC (r = 0.70, 0.81; p < 0.01, 0.001). Dompem BR declined 1–23% 6–25% (p 0.001), respectively, first three years; Cmic 0.002) %Cmic/SOC 0.610) decreased three-year onwards. Conversely, Adansam SOC, BR, Cmic, rather had irregular trends. The exchangeable acidity, sum bases, effective cation capacity negatively positively, followed pedogenic compounds, particularly dithionite-citrate iron (Fed), oxalate (Feox), lastly, pH. Therefore, understanding degree, direction, changing aspects these drivers ecosystem services necessary sustainable management practices zones.