Browsing by Author "Wanyama, J."
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Item A critical review of selected appropriate traditional evaporative cooling as postharvest technologies in Eastern Africa(Agricultural Engineering International, 2015) Obura, J. M.; Banadda, N.; Wanyama, J.; Kiggundu, N.The issue of postharvest losses (PHL) is of high importance in the efforts to combat hunger, raise income and improve food security in the world’s poorest countries. PHL of horticultural products in developing countries sometimes may reach up to 45%. PHL have an impact on food security for poor people, food quality and safety, economic development and the environment. The exact causes of PHL vary throughout the world and are very much dependent on the specific conditions and local situation in a given country. Irrespective of the level of economic development and maturity of systems in a country, PHL should be kept to a minimum. The failure to harness the physical and chemical characteristics of horticultural products using technologies has been very costly to farmers, processors and marketers in many parts of the world. A number of researchers and undocumented indigenous African Knowledge custodians in rural areas have innovated and constructed different technologies using locally available materials for the purpose of extending the shelf life of horticultural produce like vegetables. This review article seeks to critically examine some of the selected agricultural technologies and equipment used in African rural settings with view of assessing why they fail.Item Dynamics of surface runoff and soil loss from a toposequence under varied land use practices in Rwizi catchment, Lake Victoria Basin(Journal of Soil and Water Conservation, 2017) Bamutaze, Y.; Wanyama, J.; Diekrugger, B.; Meadows, M.; Opedes, H.In this study, we quantified surface runoff and soil loss along a toposequence considering four land use systems and three topographic segment positions in Rwizi catchment, Lake Victoria Basin (LVB). The land use systems were grassland dominated by a local species known as “Omugugu” (Cyperus spp.), tree plantation of pine (Pinus sabiniana) and eucalyptus (Eucalyptus globus), mulched banana (Musa Paradisiaca), and unmulched banana, topographically located on the foot slope, midslope, and summit. Runoff and soil loss magnitude and trends under varied rainfall regimes were measured using closed runoff plots measuring 2 × 20 m (40 m2). A split plot experimental design was adopted for the study. In total, 36 runoff plots were installed considering the land use and topographic factors with three replications. Observed monthly rainfall values varied from 9.3 to 167 mm (75 ± 54 mm). Annually, the registered rainfall depth was 680 mm. The annual rainfall depth was below the long-term annual mean for the area. Nearly all rainfall events with a depth greater than 10 mm contributed relatively heavy runoff, while rainfall events less than 10 mm in general caused minor surface runoff at the sites. Annual runoff within the catchment at the studied sites varied from 42 to 411 m3 ha–1 y–1. The average observed cross-site annual runoff was 151 ± 95 m3 ha–1 y–1. Results show that annual runoff was in the order of tree plantation > unmulched banana sites > grassland = mulched banana. Soil losses were greatest (1.5 t ha–1 y–1) and lowest (0.8 t ha–1 y–1) on unmulched banana and mulched banana sites, respectively. Annual soil loss showed an increase with topographic slope segment position. Average annual soil loss on the upper slope position facets (1.7 t ha–1 y–1) were 2.4 folds higher than those observed on the footslope position facets (0.7 t ha–1 y–1), giving a percentage difference of 83%. We did not detect a statistical difference in runoff (p > 0.05) due to either land use system or toposequence position. However, statistical differences were observed in soil loss (p < 0.05) for land use system and toposequence position. While the observed annual soil loss magnitude is within the tolerable thresholds, a sustained maintenance of best land use practices is still critical in maintaining the delicate balance on the fragile hillslopes in the study area.Item Effectiveness of tropical grass species as sediment filters in the riparian zone of Lake Victoria(Soil Use and Management, 2012) Wanyama, J.; Herremans, K.; Maetens, W.; Isabirye, M.; Kahimba, F.; Kimaro, D.; Poesen, J.; Deckers, J.The effectiveness of tropical grass species in strips of different length in trapping sediment from cropland was assessed, and the influence of filter length was determined. The assessment was made under natural rainfall which induced sheet and rill erosion in run-off plots and then using simulated run-off which caused concentrated erosion. The evaluated grasses were elephant grass, lemon grass, paspalum and sugarcane. Run-off plots were on a 10% slope in a randomized complete block design replicated three times. Filter lengths were 2.5, 5 and 10 m against a 10-m-long sediment source area planted with maize on a clay loam soil. The results show that sediment trapping effectiveness (TE) increases nonlinearly with increasing filter length for all grasses. Under natural rainfall, more than 70% of sediment was trapped in the first 5 m, and lengthening the strip to 10 m only resulted in a marginal increase in TE. With concentrated run-off, more than 70% of sediment was trapped in the first 5 m and lengthening the strip to 10 m resulted in a significant increase in TE. Paspalum and lemon grass performed significantly better than other grasses (P < 0.05), owing to their spreading growth pattern over the soil surface. Paspalum also has the highest root density in the upper 0.3-m layer of the soil followed by lemon grass, hence offering the greatest resistance to erosion from concentrated flow. The results demonstrate that tropical grass filter strips provide a viable means for reducing the sediment flux from cropland.Item Profiling agricultural engineering technologies for mechanizing smallholder agriculture in Uganda(Agricultural Engineering International: CIGR Journal, 2016) Wanyama, J.; Banadda, N.; Kiyimba, F.; Okurut, S.; Zziwa, A.; Kabenge, I.; Mutumba, C.; Tumutegyereize, P.; Komakech, A. J.; Kiggundu, N.Developing countries are grappling with numerous challenges including feeding rapidly growing populations, alleviating poverty, protecting the environment, and mitigating adverse impacts of climate change. For the coming years, one of the main agricultural development agenda for Sub-Saharan Africa (SSA) should be to increase agricultural productivity and production to achieve food security through agricultural mechanization with Agricultural Engineering Technologies (AETs) as major inputs. However, there is paucity of information on the status of existing AETs and their contribution to mechanizing smallholder agriculture which is crucial to effective planning and strategy formulation. Therefore, the overarching objective of this paper is to review the past and present status, the constraints to adoption and future of AETs in Uganda in the context of mechanizing smallholder agriculture. Several proven AETs developed through research institutions and universities have been profiled in different areas of farm power and mechanization systems, agro-processing for value addition; renewable energy systems; and water harnessing and utilization. Availability and prudent use of these AETs along the value chain has the potential to enhance labor use and efficiency, provide greater precision and timeliness in farm operations, reduce postharvest loses, contributing to adding value to products and profitability of farming through proper handling, drying, cleaning, grading, processing, preservation, packaging and storage. The future of AETs in Uganda is hinged on addressing the aspects on appropriateness of the AETs in the smallholder agriculture context and standardizing of AET. Furthermore, human resource capacity development through enhancement of technical skills in AE, increased private sector engagement, economic incentives and innovation protection should be an integral part of the future strategies for development and increased adoption of AETs.Item Solar fruit drying technologies for smallholder farmers in Uganda, A review of design constraints and solutions(CIGR Journal, 2016) Kiggundu, N.; Wanyama, J.; Galyaki, C.; Banadda, N.; Muyonga, J. H.; Zziwa, A.; Kabenge, I.Solar fruit drying is a technology that is successfully applied on both domestic and commercial scale among smallholder farmers in Uganda. However, existing solar drying technologies are marred with multiple deficiencies such as inefficient conversion of trapped solar radiation to meet required enthalpy, low throughput, long drying times, and inherent difficulty to achieve acceptable hygiene among others. This review critically examines existing solar drying technologies in Uganda, highlighting design constraints and plausible solutions for supporting the growing fruit drying industry. The common types of solar dryers in Uganda are the static-bed box type solar dryer model, the PPI tunnel solar dryer model, the NRI Kawanda cabinet solar dryer, the hybrid tunnel solar dryer and the UNIDO solar hybrid dryer model. Findings reveal that the challenges characterizing existing dryers in perspective of design are attributed to; poor material selection, poor mass and energy transfers, total dependence on solar energy, lack of capacity by local craftsmen to replicate new and improved models, difficulty to clean the dryers caused by inapt model configurations, and high cost of installation to mention a few. Therefore, a need exists to develop efficient and affordable designs using scientifically proven methods such as Computer Fluid Dynamics to pre-test and optimize the dryer and incorporating alternative energy sources in the design to ensure an all-weather dryer. Additionally, disseminate such innovations to farmers, retool local artisans with quality fabrication skill sets, and develop simple manual with standards and fabrication procedures for the fruit dryers.