Effect of homegarden and parkland agroforestry practices in Ethiopia on selected soil properties

Ethiopian agricultural lands are fragile due to inherent unfavourable soil properties, over-exploitation, mismanagement (deforestation, over-grazing and inappropriate land use systems) and harsh weather conditions. These factors are worsened by changing climatic conditions, leading to significant problems in terms of soil erosion and loss of soil fertility. The consequences of such processes can be detected at the economic (agricultural production is currently being jeopardized) and biological (risks of biodiversity loss and habitat fragmentation) levels. However, the use of tree/shrub species in various agroforestry practices can increase soil nutrient supply through nitrogen fixation, improve soil structure, reduce soil erosion and nutrient losses. A study was carried out in the Amhara region, Ethiopia to evaluate the effect of homegarden and parkland agroforestry practices on selected soil chemical properties. Soil samples were taken from 20x20m square plots established in homegarden agroforestry and adjacent agricultural land without trees (control). In parkland agroforestry practice, two dominant tree species in each of the five villages were chosen. Soil samples were taken from the tree at the midpoint of the canopy projection, at 0-15 and 15-30 cm depths. The collected soil samples were air-dried, homogenized and passed through a 2 mm sieve for subsequent soil chemical analysis. The results indicated that all soil chemical properties except total nitrogen were significantly (P ≤ 0.05) affected by the agroforestry practices. Higher soil organic carbon, organic matter, available phosphorus, and exchangeable potassium were found in the homegarden agroforestry practice, while the lowest values were recorded in without-tree fields (control). All soil chemical properties except soil pH decreased as the soil depth increased. Higher value of organic carbon, available phosphorus, and exchangeable potassium were found in the homegarden agroforestry likely because of a higher proportion of deep-rooted tree/shrub species and species belonging to the legume functional group. Therefore, the homegarden agroforestry practice can be used as an ecologically friendly and sustainable alternative to maintaining soil fertility

Post-mortem volatiles of vertebrate tissue

Volatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted

Low Prevalence of Conjunctival Infection with Chlamydia trachomatis in a Treatment-Naïve Trachoma-Endemic Region of the Solomon Islands

Trachoma is endemic in several Pacific Island states. Recent surveys across the Solomon Islands indicated that whilst trachomatous inflammation-follicular (TF) was present at levels warranting intervention, the prevalence of trachomatous trichiasis (TT) was low. We set out to determine the relationship between chlamydial infection and trachoma in this population. We conducted a population-based trachoma prevalence survey of 3674 individuals from two Solomon Islands provinces. Participants were examined for clinical signs of trachoma. Conjunctival swabs were collected from all children aged 1-9 years. We tested swabs for Chlamydia trachomatis (Ct) DNA using droplet digital PCR. Chlamydial DNA from positive swabs was enriched and sequenced for use in phylogenetic analysis. We observed a moderate prevalence of TF in children aged 1-9 years (n = 296/1135, 26.1%) but low prevalence of trachomatous inflammation-intense (TI) (n = 2/1135, 0.2%) and current Ct infection (n = 13/1002, 1.3%) in children aged 1-9 years, and TT in those aged 15+ years (n = 2/2061, 0.1%). Ten of 13 (76.9%) cases of infection were in persons with TF or TI (p = 0.0005). Sequence analysis of the Ct-positive samples yielded 5/13 (38%) complete (>95% coverage of reference) genome sequences, and 8/13 complete plasmid sequences. Complete sequences all aligned most closely to ocular serovar reference strains. The low prevalence of TT, TI and Ct infection that we observed are incongruent with the high proportion of children exhibiting signs of TF. TF is present at levels that apparently warrant intervention, but the scarcity of other signs of trachoma indicates the phenotype is mild and may not pose a significant public health threat. Our data suggest that, whilst conjunctival Ct infection appears to be present in the region, it is present at levels that are unlikely to be the dominant driving force for TF in the population. This could be one reason for the low prevalence of TT observed during the study