Effects of charcoal production on soil physical properties in Ghana

Charcoal production, widespread in Ghana like in other W African countries, is a major driver of land-cover change. Effects of charcoal production on soil physical, including hydrological, properties, were studied in the forest-savannah transition zone of Ghana. Core and composite samples from 12 randomly selected sites across the width of Kotokosu watershed were taken from 0-10 cm layer at charcoal-site soils and adjacent field soils (control). These were used to determine saturated hydraulic conductivity (K-sat), bulk density, total porosity, soil texture, and color. Infiltration rates, surface albedo, and soil-surface temperature were also measured on both sites. The results showed that the saturated hydraulic conductivity of soils under charcoal kilns increased significantly (p < 0.01) from 6.1 +/- 2.0 cm h(-1) to 11.4 +/- 5.0 cm h(-1), resulting to a relative increase of 88%. Soil color became darkened under charcoal kilns with hue, value, and chroma decreasing by 8%, 20%, and 20%, respectively. Bulk density on charcoal-site soils reduced by 9% compared to adjacent field soils. Total porosity increased from 45.7% on adjacent field soils to 50.6% on earth kilns. Surface albedo reduced by 37% on charcoal-site soils while soil-surface temperature increased up to 4 degrees C on average. Higher infiltration rates were measured on charcoal-site soils, which suggest a possible decrease in overland flow and less erosion on those kiln sites.