Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy cla...Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy clay in contrast to the sandy clay loam of the surface soils. Translocation of fine to medium sized soil materials influenced the relatively higher bulk density (>1.60 Mg/m3) and contents of organic carbon, nitrogen and exchangeable bases in the mounds. Kaolinite was the dominant clay mineral with pH values generally below 5.3 in all the soils reflecting the weathered tropical soil environment. Dispersion ratio values, which were 0.5 for the surface soils, indicated greater stability of the mound due to aggregate cementing action by the termites. Estimated mound density was about 120 mounds per ha, which tied in with known groundwater reserves at the study sites. Majority of the mounds exhibited a cone-shaped morphology with heights varying between 3.05-4.00 m in the Rhodic Acrisol and 2.05-4.20 m in the Haplic Acrisol with corresponding estimated total mass of 96,361 kg and 54,910 kg per 1000 m2 land area. These estimates represented a large amount of material relative to the 25,000-26,000 kg of surface soil material within the same unit area. The K in the surface soils ranged from 3.3 x 10-5 to 5.0 x 10-5 m/s while the value for the mound was ≤0.5 x 10-5 m/s. Lower porosity, θ;the effect was more pronounced when the mound was applied on the soil surface. Improvement in water retention and nutrient availability to plants and prevention of leaching to avoid groundwater contamination are some of the positive attributes of this study.展开更多
Three land use types (natural fallow, Leucaena leucocephala woodlot and cultivated plots) on a Ferric Acrisol in a semi-arid tropical zone of Ghana were compared to assess their effects on variability in selected soil...Three land use types (natural fallow, Leucaena leucocephala woodlot and cultivated plots) on a Ferric Acrisol in a semi-arid tropical zone of Ghana were compared to assess their effects on variability in selected soil properties and plant biomass accumulation. Organic carbon accumulation in the representative natural fallow profile was 22.7 g/kg, followed by 16.5 g/kg for the Leucaena woodlot and lastly 11.8 g/kg for the cultivated site. The mean bulk density of the natural fallow, Leucaena woodlot and cultivated sites were from 1.36 Mg/m3, 0.92 Mg/m3 and 1.33 Mg/m3 with corresponding range in mean weight diameter of 0.5 mm - 1.2 mm, 0.6 mm - 1.2 mm and 1.0 mm - 1.2 mm, respectively. The lower bulk density observed for the woodlot corresponds to increased total porosity, aeration, and root proliferation due to the stronger and extensive rooting system. Significant differences (P >36%). For the surface soils, exchangeable Na was very variable in the natural fallow. Exchangeable Na, Ca and K and total nitrogen were very variable in the Leucaena woodlot and the cultivated sites. Variability in clay content was very high in the cultivated soils only. The order cultivated land > Leucaena woodlot > natural fallow was noted for properties with high variability (CV > 36%). Plant biomass accumulation was 1834 kg/ha (natural fallow) and 830 kg/ha (Leucaena woodlot) indicating that natural fallows do not only maintain soil quality but they also decrease variability in soil properties which is desirable for soil productivity and quality.展开更多
文摘Characteristics of termite mounds and associated Rhodic Acrisol and Haplic Acrisol in the coastal savanna zone of Ghana and their impact on hydraulic conductivity were assessed. The texture of the mounds was sandy clay in contrast to the sandy clay loam of the surface soils. Translocation of fine to medium sized soil materials influenced the relatively higher bulk density (>1.60 Mg/m3) and contents of organic carbon, nitrogen and exchangeable bases in the mounds. Kaolinite was the dominant clay mineral with pH values generally below 5.3 in all the soils reflecting the weathered tropical soil environment. Dispersion ratio values, which were 0.5 for the surface soils, indicated greater stability of the mound due to aggregate cementing action by the termites. Estimated mound density was about 120 mounds per ha, which tied in with known groundwater reserves at the study sites. Majority of the mounds exhibited a cone-shaped morphology with heights varying between 3.05-4.00 m in the Rhodic Acrisol and 2.05-4.20 m in the Haplic Acrisol with corresponding estimated total mass of 96,361 kg and 54,910 kg per 1000 m2 land area. These estimates represented a large amount of material relative to the 25,000-26,000 kg of surface soil material within the same unit area. The K in the surface soils ranged from 3.3 x 10-5 to 5.0 x 10-5 m/s while the value for the mound was ≤0.5 x 10-5 m/s. Lower porosity, θ;the effect was more pronounced when the mound was applied on the soil surface. Improvement in water retention and nutrient availability to plants and prevention of leaching to avoid groundwater contamination are some of the positive attributes of this study.
文摘Three land use types (natural fallow, Leucaena leucocephala woodlot and cultivated plots) on a Ferric Acrisol in a semi-arid tropical zone of Ghana were compared to assess their effects on variability in selected soil properties and plant biomass accumulation. Organic carbon accumulation in the representative natural fallow profile was 22.7 g/kg, followed by 16.5 g/kg for the Leucaena woodlot and lastly 11.8 g/kg for the cultivated site. The mean bulk density of the natural fallow, Leucaena woodlot and cultivated sites were from 1.36 Mg/m3, 0.92 Mg/m3 and 1.33 Mg/m3 with corresponding range in mean weight diameter of 0.5 mm - 1.2 mm, 0.6 mm - 1.2 mm and 1.0 mm - 1.2 mm, respectively. The lower bulk density observed for the woodlot corresponds to increased total porosity, aeration, and root proliferation due to the stronger and extensive rooting system. Significant differences (P >36%). For the surface soils, exchangeable Na was very variable in the natural fallow. Exchangeable Na, Ca and K and total nitrogen were very variable in the Leucaena woodlot and the cultivated sites. Variability in clay content was very high in the cultivated soils only. The order cultivated land > Leucaena woodlot > natural fallow was noted for properties with high variability (CV > 36%). Plant biomass accumulation was 1834 kg/ha (natural fallow) and 830 kg/ha (Leucaena woodlot) indicating that natural fallows do not only maintain soil quality but they also decrease variability in soil properties which is desirable for soil productivity and quality.
