Differential Impacts of Cropland Expansion on Soil Biological Indicators in Two Ecological Zones
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Date
2023
Authors
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Journal ISSN
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Publisher
MDPI
Abstract
Agricultural expansion in Sub-Saharan Africa is characterized by different farm ages in
smallholder communities. This study investigated changes in microbial indices broadly (i) at the
reconnaissance survey level in four agro-ecological zones and (ii) in different farms at the forest
(Dompem) and forest–savanna transition (Adansam) zones, as influenced by the duration of cultivation.
Soils from one-year (first cultivation of cleared forest/fallow), three-year, five-year, and ten-year
farms were analyzed for basic soil properties, active or labile carbon (POXC), basal respiration (BR),
microbial biomass (Cmic) using permanganate oxidizable C, alkali trap, and chloroform fumigation
incubation. In both study levels, POXC content was <1% of soil organic carbon (SOC) in all zones,
higher in the wet agro-ecological zones, and positively correlated with SOC (r = 0.70, 0.81; p < 0.01,
p < 0.001). Dompem SOC and BR declined by 1–23% and 6–25% (p < 0.001), respectively, in the first
three years; Cmic (p = 0.002) and %Cmic/SOC (p = 0.610) decreased from three-year farms onwards.
Conversely, the Adansam SOC, BR, Cmic, and %Cmic/SOC rather had irregular trends. The microbial
indices were influenced by exchangeable acidity, the sum of exchangeable bases, and effective cation
exchangeable capacity negatively or positively, followed by SOC, pedogenic compounds, particularly
dithionite-citrate iron (Fed), oxalate iron (Feox), and lastly, soil pH. Therefore, understanding the
degree, direction, and changing aspects of these drivers of soil ecosystem services is necessary for
sustainable soil management practices in different agro-ecological zones.
Description
Research Article
Keywords
basal respiration, farm types, metabolic quotient, labile carbon, microbial biomass
Citation
Citation: Neina, D.; Agyarko-Mintah, E. Differential Impacts of Cropland Expansion on Soil Biological Indicators in Two Ecological Zones. Sustainability 2023, 15, 8138. https:// doi.org/10.3390/su15108138