No abstract

Background Land-use systems that sequester carbon and reduce CO2 emissions are key in the global mitigation strategies of climate change. Greenhouse gas emission from agro-ecosystems in sub-Saharan Africa is little studied. Here, we quantified soil carbon stock (SCS) and CO2 emissions from three land-use systems viz. arable land, oil palm plantation and forestland in the semi-deciduous forest zone of Ghana. Results Soil organic carbon concentration at the 0–15 cm layer in the forestland was 62 and 23% greater than that in the arable land and palm plantation, respectively. The SCS along the 1.0-m profile was 108.2, 99.0 and 73.5 Mg ha−1 in the forestland, palm plantation and arable land, respectively. Arable land emitted 30–46% more CO2 than palm plantation and forestland. In the dry season, CO2 emissions were respectively 0.93, 0.63 and 0.5 kg ha−1 h−1 from the arable land, palm plantation and forestland. Positive relationships were observed between CO2 emissions and SCS, soil temperature, and moisture. The SCS greatly influenced CO2 emission in the dry season more than in the wet season in the relatively higher carbon-input systems (forestland and palm plantation). Soil temperature accounted for more than 55% of CO2 emissions in both seasons, which has implications in the era of rising global temperatures. Conclusions The study provides relevant information on carbon storage abilities of the three land-use types in tropical climate and calls for drastic climate change actions to reduce degradation of forest cover and soil disturbance in agro-ecosystems in sub-Saharan Africa.

Land use conversion significantly impact on sensitive soil quality parameters such as microbial biomass and soil microbial quotient. Therefore, soil microbial biomass and physicochemical properties were compared under three different land use systems namely agricultural land, degraded mine land and an adjacent natural forest in the Newmont Gold Ghana Limited concessional areas, Kenyasi, Ghana. In our field experimentation, an area of 300 m2 was demarcated in each land use type for soil sampling. In each of the land use type, we collected soil 5 samples at a depth of 0-15 cm in both the dry and wet seasons respectively. Parameters we measured included soil bulk density, pH, particle size distribution, organic carbon, total nitrogen, available phosphorus, microbial biomass carbon and nitrogen, and moisture content. Our results revealed that land use type significantly impacted on soil microbial biomass and physicochemical properties. Microbial biomass carbon and nitrogen was higher in the forested land compared to the agricultural land and degraded mine land, which was due to relatively higher amounts of litter inputs. Microbial biomass carbon decreased between 20.23 - 88.36% when land use changed from forested land to other land uses. Significant positive correlation was observed between soil microbial biomass and water content, soil organic carbon, phosphorus, clay, nitrogen. Generally, seasonal variation in our study area did not influence soil physical and chemical properties, however, it significantly affected microbial biomass indices. Findings of our study further revealed the importance of forested area in the maintenance of soil quality parameters.