A mobile, in-situ soil bin test facility to investigate the performance of maresha plough

Ethiopia is well known for its use of an ard plough dating from antiquity – maresha – which fractures and disturbs the soil. However, hardly any notable progress of experimental research on this animal drawn tillage tool in the field has been made. The attendant problems in current practise are soil-maresha interaction, viz., uneven oxen strength along with different pace of walking, uncontrolled implement behaviour, and field conditions. Taking stock of the experimental research on animal drawn tillage tools in general, most of the documented works on the dynamics of the interaction between soil and animal drawn tillage tools tend to rely on trial-and-error based on factors mainly based on experience and cultural context. As such, no research tailored to systematically handle the link between maresha plough and soil bin experiments exists. To this aim, this study developed a mobile in-situ soil bin facility in which the system was calibrated, tested, and evaluated under outdoor experimental conditions, wherein online measurements of draught, speed, and depth of tillage were carried out. The insights and observations gained from the experimentation were discussed and reported in terms of smooth run, overload, cyclic forces, zero speed with minimal force, stoppage, speed measurement with no force, force measurement with no speed, and low speed with low force

Effect of side-wings on draught: The case of Ethiopian Ard plough (maresha)

Ethiopian farmers have been using an ox-drawn breaking plough, known as ard plough – maresha, for thousands of years. Maresha is a pointed, steel-tipped tine attached to a draught pole at an adjustable shallow angle. It has narrow side-wings, attached to the left and right side of it, to push soil to either side without inverting. The aim of this paper is to explore the effect of side-wings on draught using a field soil bin test facility. To this end, a mobile and an in-situ soil bin test system, for online measurements of draught, was designed and developed. This research considered tool geometry (maresha plough with and without side-wings) and rake angle (shallow – 8°, medium deep – 15°, and deep – 24°, representing primary, secondary and tertiary tillage processes in Ethiopia, respectively). Maresha plough with side-wings has greater contact area, between the moving soil and tool, than its wingless counterpart. When the ploughshare surface and soil slide relative to one another, the draught expected to increase with contact area, as adhesion and friction resistance increases with area. However, experimental analysis indicated that the maresha with side-wings required less draught compared to maresha without side-wings (ρ < 0.001). This might be attributed to the effect of side-wings on crack propagation by a wedging effect to enhance and facilitate subsequent ploughing. This paper also dealt with the effect of rake angle on draught. Though the depth setup was getting smaller d1 < d2 < d3 for the successive tillage runs, analysis showed increment in draught force (ρ < 0.001) with rake angle. This might be attributed to higher soil compaction that comes with depth and downward force resulting from repeated use of maresha every season to the same depth for thousand years. Although more and rigorous studies should be undertaken considering soil, tool, and operational parameters to arrive at conclusive results, this paper gave some insights regarding effect of side-wings on maresha plough and rake angle on draught. This shows that there is still room for improvement of maresha plough geometry for minimum draught requirement and optimum soil manipulation

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Investigating the soil-maresha plough interaction using a mobile, in-situ testing device

The ard plough – maresha dates from antiquity and is used in Ethiopia. The Maresha is a non-inverting tillage tool consisting of a steel-tipped tine attached to a draught pole at an adjustable shallow angle. It has narrow side-wings, attached to the left and right side of it, to push soil to either side. Most work on the interaction between soil and maresha is documented as trial-and-error procedures based on experience in a cultural context. In experimental research on the maresha plough, challenges arise from uneven oxen strength along with different pace of walking, uncontrolled implement behaviour, and rough field conditions. No research has ever systematically investigated the link between the maresha plough and soil characteristics. There is a lack of information on the effect of maresha’s side-wings and tillage angle on draught requirement and soil loosening. The aim of this research was to investigate the soil-maresha plough interaction and, more specifically, the effect of tillage angle and side-wings on draught and soil loosening. In this study a mobile soil bin facility was developed as an in-situ testing device. The developed soil bin has three rows (track-rails) with four rail lines - for three parallel experimental lines. The easy disassembly and relocation of the rails make that the testing device can be moved around a terrain or between fields, depending on the experimental requirements. The instrumentation and data acquisition system was mounted on a carriage and included load cells, linear variable displacement transducers (LVDT), and an optical encoder. The design parameters for the experiments were: (1) tool geometry - winged and wingless maresha, and (2) rake angles (for shallow, medium deep, and deep, representing primary, secondary, and tertiary tillage processes in Ethiopia, respectively). The operating parameters were tool travel speed and tillage depth. The experimental soil was classified as Vertisol. The additional variables were furrow area, moisture content, bulk density, rock fragments, and penetrometer resistance. The winged maresha plough has a greater contact with the moving soil than its wingless counterpart. Here the draught was expected to increase with contact area, as adhesion and friction resistance increases with area. However, results showed that the winged maresha plough required lower draught than wingless maresha. The side-wings stimulate in these soils most likely the crack propagation by a wedging effect and thereby enhance and facilitate subsequent ploughing by reducing the soil resistance ahead of the ploughshare. Results showed that draught increased with rake angle as could be expected. Similarly, an increased operating depth had a positive correlation with draught requirement. Experimental limitations and difficulties came from the use of a walking tractor as pulling source. Under some conditions variability in soil surface and soil cover by plants can cause variable wheel slippage resulting in a change in pulling force and changing travel speed. Experimental runs also encountered difficulties in fields with large buried rock fragments as these would stop the forward movement and sometimes caused damage to the tool. This is in line with farmers’ actions to remove bigger rock fragments from the field. On the other hand, it was found that the presence of small rock fragments in the soil tends to reduce draught requirement with higher tool travel speed and facilitate tillage. Again this is in line with the reluctance of farmers to take away the smaller rock fragments (i.e. < 5 cm across) from their fields, since they also believe these benefit soil moisture conservation and protect topsoil from erosion. The penetrometer recording showed the presence of a plough pan at depth between 10 and 15 cm below the soil surface. This emphasises the need to locally destroy the plough pan by occasional deep ploughing. The developed soil bin facility can be used as a platform for controlled experiments with different tillage tool geometry types to get information on how geometry affects draught and soil manipulation. Since the facility is mobile and allows in-field experimentation it can be used in different types of soils for tillage tool studies. Further, with minor alterations, the system can also be used in soil-wheel interaction (traction) studies.status: publishe

Animal health service delivery in crop-livestock and pastoral systems in Ethiopia

Livestock diseases are a priority problem for livestock keepers throughout Ethiopia. Livestock keepers have also singled out poor animal health service delivery, which is largely the domain of the public sector, as the major constraint to improving animal health and productivity. In the current study, we describe the animal health service delivery system and compile from five questionnaire surveys involving 4,162 livestock keepers to characterize animal health service delivery in Ethiopia. The mapping of the animal health service delivery system along the livestock value chain clearly highlights the role of informal animal health services and variations of roles of the private sector. Also, the survey results clearly showed that livestock keepers' access to, use of and satisfaction with animal health services significantly varied across livestock production systems, geographic locations, socioeconomic strata, and service providers. Livestock keepers in crop-livestock and agropastoral systems had 5.5 (odds ratio = 5.453, P = 0.000) and 2.5 (odds ratio = 2.482, P = 0.000) times more access to services in reference to the pastoral system. In reference to private veterinary clinics, livestock keepers reported higher access to services provided by all the other service providers, particularly to services provided by extension agents, drug shops and CAHWs. Similarly, better access was reported by male than female (odds ratio = 1.098; P = 0.025) and wealthier than poorer (odds ratios = 1.40-1.79; P = 0.000) farmers and pastoralists. In general, low access to services was reported, 32.7, 25.2, and 19.3% of the respondents reporting access in crop-livestock, agropastoral and pastoral systems, respectively. Effective demand for services was evaluated through proxy variables, namely number of visits to service providers and health expenditures over a year. Highland farmers used the services more often than pastoralists (odds ratio = 2.86; P = 0.000), but pastoralists' expenses were significantly higher. Wealth (measured by livestock owned), gender and age also had significant effects on the use of services and expenditure on services. Satisfaction with services was evaluated based on four measures, namely availability (av), accessibility (ac), quality (qw), and timeliness (tm) of services. The average scores (out of 10) for av, ac, qw, and tm were 6.1, 5.9, 6.2, and 5.7, respectively. Principal component analysis was conducted to derive the latent variable "satisfaction" from the four measures, extracted only one factor, indicating the four variables are measuring the same construct (satisfaction). Regressing the latent variable satisfaction on the four measures gave significant (P = 0.000) b values of 0.22, 0.20, 0.13, and 0.14 for av, ac, qw, and tm, respectively, indicating strong relationships between the latent variable satisfaction and its measures. There was a significant dissatisfaction with the public sector, with average scores of 0.06 and 0.19 for the public and private service providers, respectively. It can be concluded that livestock keepers in remote regions of the country, pastoralists, women, poorer, and older livestock keepers have less access to services. Satisfaction with services is low to medium and the major concerns of livestock keepers appears to be availability and accessibility of services. Based on our findings, we recommend an integrated, multi-sectoral involvement to improve the veterinary service delivery through improved veterinary infrastructure, public-private partnership, and animal health information system across the various livestock production systems