Soil carbon management practices, knowledge of climate change and CO2 emission of some land use types in Ogbomoso Agricultural Zone, Oyo State, Nigeria

The design and implementation of land use management types that would minimize degradation and sustain productivity will require an understanding of the soil dynamic processes that prevail under the different land use types and different ecological zones. This paper investigated four land use types, farmer’s soil management practices, knowledge of climate change and effects of land use types on soil carbon and CO2 emissions in Ogbomoso Agricultural Zone, south-western Nigeria. Multistage sampling techniques were used to select 200 respondents from five Local Government Areas (LGAs) in 20 villages. Information on socio-economic factors, current cropping practices, knowledge of soil types, properties, climate and crop and soil management history was elicited from the respondents. Soil samples from the various land use system were evaluated, while land use system and CO2 emission were determined. Data were collected with the use of structured questionnaires and described using frequency counts and percentages while Pearson’s Product Moment Correlation (PPMC) was used to test the existence of relationships between the pairs of variables. Majority of the respondents were married and had basic education. Fertilizer usage was at the following level, inorganic fertilizers (59%), Manure (27%), compost (14%) and 44% of them have used at least compost, manure or inorganic fertilizers once. Forty-six percent (46%) relied on personal observation as source of climate change knowledge while 91% had ploughed their farm once and 55% had burnt their land once. Sex (r = 0.356**), age(r = 0.383**), education (r = 0.265**) and source of climate change knowledge (r = 0.216*) had decisive influence on the knowledge of climate change among the respondents. On average, maize farms across the two LGAs showed SOC stock deficits of 174,296 kg ha-1 corresponding to an emission of about 639,084.68 kg CO2e ha-1. Effective land management practices should be adopted for enhanced carbon sequestration, climate change mitigation, sustained fertility status and increased agricultural productivity

Location and Land use effects on Soil Carbon Accretion and Productivity in the Coastal Savanna Agro-ecological Zone of Ghana

Land use type, climate and soil properties are major determinants of soil carbon storage and productivity, especially in low-input agriculture. In this study, we investigated the interactions among these factors at four (4) locations, namely Accra Metropolis, Ga West, Ga East and Shai Osudoku, within the Coastal-Savannah agro-ecological zone of Ghana. The land use types were maize-based cropping, cassava-based cropping, woodlot/plantations and natural forests. The impact of these on soil productivity at a given location was assessed in terms of soil carbon stocks and a Soil Productivity Index (SPI). The SPI is a composite value derived from routine soil properties such as: soil texture, available water capacity, pH, cation exchange capacity, soil organic carbon, available P, exchangeable K, potentially mineralizable nitrogen, and basic cations, among others. Principal component analysis was used to select soil properties that were used to estimate SPI. The results showed that the locations differed with respect to rainfall regimes and soil types. Locations with slightly heavier soil texture and relatively higher rainfall regimes (Ga East and Shai Osudoku) had significantly higher soil carbon storage and SPI values than the lighter soil textured locations (Accra Metropolis and Ga West). With regards to land use, forest had significantly higher soil carbon storage and SPI than all the other land use types, irrespective of location. The order of soil carbon storage and SPI were: forest > woodlot/plantation > cassava > maize. It was observed that though the Accra Metropolis location hosted the oldest forest, soil carbon was still low, apparently due to the lighter soil texture. We concluded that the soil productivity restorative ability is an interactive effect of carbon management (land use), soil texture and other properties. This interaction hitherto has not been adequately investigated, especially in low-input agriculture

Acquisition of Human-Type Receptor Binding Specificity by New H5N1 Influenza Virus Sublineages during Their Emergence in Birds in Egypt

Highly pathogenic avian influenza A virus subtype H5N1 is currently widespread in Asia, Europe, and Africa, with 60% mortality in humans. In particular, since 2009 Egypt has unexpectedly had the highest number of human cases of H5N1 virus infection, with more than 50% of the cases worldwide, but the basis for this high incidence has not been elucidated. A change in receptor binding affinity of the viral hemagglutinin (HA) from α2,3- to α2,6-linked sialic acid (SA) is thought to be necessary for H5N1 virus to become pandemic. In this study, we conducted a phylogenetic analysis of H5N1 viruses isolated between 2006 and 2009 in Egypt. The phylogenetic results showed that recent human isolates clustered disproportionally into several new H5 sublineages suggesting that their HAs have changed their receptor specificity. Using reverse genetics, we found that these H5 sublineages have acquired an enhanced binding affinity for α2,6 SA in combination with residual affinity for α2,3 SA, and identified the amino acid mutations that produced this new receptor specificity. Recombinant H5N1 viruses with a single mutation at HA residue 192 or a double mutation at HA residues 129 and 151 had increased attachment to and infectivity in the human lower respiratory tract but not in the larynx. These findings correlated with enhanced virulence of the mutant viruses in mice. Interestingly, these H5 viruses, with increased affinity to α2,6 SA, emerged during viral diversification in bird populations and subsequently spread to humans. Our findings suggested that emergence of new H5 sublineages with α2,6 SA specificity caused a subsequent increase in human H5N1 influenza virus infections in Egypt, and provided data for understanding the virus's pandemic potential