Plant litter turnover, soil chemical and physical properties in a Ghanaian gold- mined soil revegetated with Acacia species

Abstract

The effects of stand-age of Acacia sp on plant litter turnover and decomposition, soil physical properties and nutrient elements were studied in revegetated gold-mined soils. Litter in the 3- and 6-year plantation soils were significantly lower (P < 0.05) than the forest soil, whilst 9- and 12-year old revegetated soils had litter significantly higher (P < 0.05) than the forest soil. Biomass decomposition constants measured in all treatments were statistically similar, ranging from 1.03 in the forest soil to 0.94 in the revegetated treatments. Total N concentrations were higher in the forest, 12- year and 9- year revegetated treatments and varied from 0.20% to 0.50%. Organic carbon concentrations followed the increasing trend 3- year < 6- year < 9-year < 12- year < forest. Exchangeable K concentrations measured in all the soils were lower than 0.6 cmol kg,-1 . Field moisture capacity (12.6 – 20.3 %) and infiltration rates (25.2 – 31.1 cm h-1 ) in the 3-year, 6-year and 9-year stands were significantly lower than in the forest and 12-year stand whilst soil bulk density values were higher in the 3-year, 6-year and 9-year than in the forest and 12- year stands. The study indicates that after 12 years of revegetation with Acacia sp, soil physical characteristics such as bulk density, moisture holding capacity and infiltration rates improved to levels comparable to those found under un-mined soils and that revegetation is a good strategy for restoring the fertility of gold-mined soils