Duration of Cultivation Has Varied Impacts on Soil Charge Properties in Different Agro-Ecological Zones of Ghana

Abstract

Agricultural expansion into natural habitats causes soil fertility decline after a period of cultivation. This study investigated changes in soil exchange properties in different farm types at Dompem and Adansam in the Forest and Forest–Savannah transition zones of Ghana as influenced by the duration of cultivation. Sixty farms were selected for soil sampling through a reconnaissance survey. The soils were subjected to physicochemical analysis. The results showed that the Dompem soils were loamic, had more amorphous Fe and Al oxides, were strongly acidic and had low contents of exchangeable acidity, a low sum of exchangeable bases (SEB), low effective cation exchangeable capacities (ECECs) and low available P. Conversely, the Adansam soils were arenic, slightly acidic and had relatively higher SEBs and ECECs. Interestingly, soil organic carbon (SOC) in the Dompem soils declined by >10% in relation to the duration of cultivation and showed rapid reductions within three years. Correspondingly, soil bulk density, CEC and SEB declined. In Adansam soils, only δpH declined in relation to the duration of cultivation. Soil organic carbon accounted for >50% of the ECEC and 49% of the SEB in Dompem soils but 36% of δpH in the Adansam soils. In conclusion, agricultural expansion, manifested in the duration of cultivation, mainly influenced soil charge properties through SOC decline.

Keywords

• native vegetation
• fallow
• soil degradation
• effective cation exchange capacity
• pedogenic compounds
• Delta pH