Effect of land-use conversion from forest to cocoa agroforest on soil characteristics and quality of a Ferric Lixisol in lowland humid Ghana

• Published in: Agroforestry systems 2014-02, Vol.88 (1), p.87-99
• Main Authors: Dawoe, Evans K, Quashie-Sam, James S, Oppong, Samuel K
• Format: Article
• Language: English
• Subjects: acid soils; Acidic soils; Agricultural practices; Agricultural production; Agriculture; Agroforestry; Agronomy. Soil science and plant productions; base saturation; Biological and medical sciences; Biomedical and Life Sciences; bulk density; carbon sinks; Cation exchange; cation exchange capacity; Chemical properties; Cocoa; Cover crops; Deciduous forests; Deforestation; exchangeable calcium; Farm management; Forest management; Forestry; forests; Fundamental and applied biological sciences. Psychology; Land use; land use change; Life Sciences; nitrogen content; Organic carbon; physicochemical properties; Plantations; Porosity; shade trees; Soil degradation; Soil density; Soil depth; Soil fertility; soil organic carbon; Soil quality; soil resources; Soil sciences
• ISSN: 0167-4366; 1572-9680
• DOI: 10.1007/s10457-013-9658-1

Soil fertility decline caused by deforestation, soil degradation and low input use has become a primary factor limiting sustainable utilization of soil resources in cocoa agroforestry systems on acid soils in lowland humid Ghana. Changes in and responses of soil physico-chemical properties and soil quality to land-use change was investigated along a chronosequence of farm fields on a Ferric Lixisol in the Ashanti region of Ghana. Soil bulk density increased significantly only in the top 0–10 cm soil layer. Concentrations and stocks of soil organic carbon (SOC) and total N decreased significantly in the top 0–10 and 10–20 cm soil depths. By 30 years after forest conversion, cocoa system had re-accumulated up to 38.8 Mg C ha⁻¹ or 85 % of initial forest carbon stock values. Total porosity (%) decreased significantly in shaded-cocoa fields in comparison with the natural semi-deciduous forest. An assessment of soil deterioration using degradation indices (DIs) revealed that total soil quality (0–20 cm) deteriorated significantly (DI = –60.6) in 3-year-old of cocoa system but improved in 15 and 30-year-old systems. Available P stocks declined consistently while soil exchangeable Ca, K and Mg stocks as well as cation exchange capacity (CEC) and base saturation remained more or less stable with a tendency to improve. The inclusion of leguminous shade trees during early plantation development, development of mechanisms for the integration of cover crops and enhancement of farmer capability in improved farm management are required to maintain high C and nutrient base, minimize soil quality degradation during plantation development phase and sustain long-term productivity.