Department of Engineering Sciences and Technology

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A ‘Smart’ approach on fluoride removal: detection in water sources and removal with biomass
(Sokoine University of Agriculture, 2020-01) Mwakabona, Hezron
Fluoride is one of the common minerals found in natural water, ingestion of which, at moderate concentration, is linked to good dental health. However, ingestion of higher concentrations of this mineral over a period is responsible for fluorosis, a disorder characterised by mottling of teeth and skeletal deformations. Therefore, the WHO sets the highest permissible level of this mineral in drinking water at 1.5 mg/L to limit its effect on public health. Consequently, a water source with fluoride concentration above this highest permissible level is regarded as unfit for human consumption, hence, requiring a treatment before consumption. As such, several studies have explored different low-cost methods to detect and remove this contaminant from drinking water. These include defluoridation and detection of fluoride by plant biomass and iron-based materials, respectively. These materials arc attractive because they have a potential for providing efficacious and cost-effective methods to deal with this water contaminant. In this thesis, the challenges delaying their field application (in detection and removal) of fluoride arc identified and suitable solutions are presented. Furthermore, the properties of iron that make it suitable for fluoride detection and removal enhancement in aqueous media arc presented. A critical review of the studies published over the past three decades on water defluoridation by non-aciivated biomass reveals that, most studies explorc extensively only the defluoridation efficiency/capacily ofthese materials. This bias in studied properties is shown to be due to inadequacy in selection of study parameters, where, the defluoridation mechanisms are poorly studied. This could have resulted in the current poor understanding of their defluoridation mechanisms. Therefore, lessons from these studies were used to identify and propose the “must include” parameters to direct the future studies for better understanding of their defluoridation properties, especially, the defluoridation mechanisms. These are: effect of solution pH, point of zero charge and surface functional groups characterisation before and after material use. For plant biomass ash, the major challenge associated with its application in water defluoridation was found to be related to media-induced contamination of the treated water, notorious being the elevation of the pH of the treated water. This challenge could have repelled many possible applications of this material in water treatment besides its great potentials as water treatment material. In this study, the Cyperus plants were successfully
Access to formal credit and its linkace with agricultural technologies adoption: a case of smallholder farmers ln Zanzibar
(Sokoine University of Agriculture, 2009) Mohamed, Khalid Salim
This study was conducted in order to determine the extent of access to formal credit in rural Zanzibar and identify factors that influence smallholder farmers* access to formal credit. It also aimed to assess the linkage between access to credit and the adoption of agricultural technologies. In conducting the study, both primary and secondary data were collected. In the collection of primary data, questionnaires were administered to 750 randomly selected smallholder farmers. The data collected were analyzed descriptively and quantitatively. The results from the study reveal that outreach and access of formal credit in the study areas is low. About 78% of sampled households were found to be credit constrained. It was also revealed that 41% of the credit constrained households were relatively members of the more poor group in the study areas, while only 10% of the non-credit constrained belonged to this group. Furthermore, the study results suggest that the number of times one has received formal credit, keeping livestock, having a bank account, value of productive assets owned and household total income are important factors in influencing smallholder farmers* access to formal credit. The findings also show that the intensity of extension contacts, household size, and the value of productive assets are important factors in influencing agricultural technology adoption among non credit households, while the number of times one has ever received formal credit was found to have more influences in inducing technology adoption among credit constrained households. Based on these findings, it is recommended that smallholder farmers should be availed the opportunities of getting repeat loans in order to improve their chances of accessing credit in the formal credit markets and enhance adoption of agricultural technologies. Farming households can as well be encouraged to diversify their income sources within and away from agricultural activities through promotion of mixed farming and off-farm activities. The need to develop a saving culture in the farming communities is also crucial for ensuring the creation of sustainable and efficient financial system. Furthermore, it is recommended that in order to enhance adoption of agricultural technologies, extension services should be targeted to non-credit constrained households.
Accuracy of Giovanni and Marksim software packages for generating daily rainfall data in selected bimodal climatic areas in Tanzania
(Tanzania Journal of Agricultural Sciences, 2014) Kahimba, F. C.; Tumbo, S. D.; Mpeta, E.; Yonah, I. B.; Timiza, W.; Mbungu, W.
Agricultural adaptation to climate change requires accurate, unbiased, and reliable climate data. Availability of observed climatic data is limited because of inadequate weather stations. Rainfall simulation models are important tools for generating rainfall data in areas with limited or no observed data. Various weather generators have been developed that can produce time series of climate data. Verification of the applicability of the generated data is essential in order to determine their accuracy and reliability for use in areas different from those that were used during models development. Marksim and Giovanni weather generators were compared against 10 years of observed data (1998-2007) for their performance in simulating rainfall in four stations within the northern bimodal areas of Tanzania. The observed and generated data were analyzed using climatic dialog of the INSTAT program. Results indicated that during the long rain season (masika) Giovanni predicted well the rainfall amounts, rainy days, and maximum dry spells compared to Marksim model. The Marksim model estimated seasonal lengths much better than the Giovanni model during masika. During short rain season (vuli), Giovanni was much better than Marksim. All the two software packages had better predictions during masika compared to vuli. The Giovanni model estimated probabilities of occurrence of rainfall much better (RMSE = 0.23, MAE = 0.18, and d =0.75) than Marksim (RMSE = 0.28, MAE = 0.23, and d = 0.63). The Marksim model over-predicted the probabilities of occurrence of dry spells greater than seven days (MBE = 0.17) compared to the Giovanni model (MBE = 0.01). In general the Giovanni model was more accurate than the Marksim model in most of the observed weather variables. The web based Giovanni model is better suited to the northern bimodal areas of Tanzania. The Marksim model produced more accurate climatic data when the long-term average climate data are used as input variables. This study recommends the use of rainfall data generated using Giovanni software over Marksim, for areas receiving bimodal rainfall regimes similar to the northern bimodal areas of Tanzania.
Adaptations in water harvesting technologies for enhancing food security and livelihood: A multi-country study in Sub-Saharan Africa
(Springer, 2018) Snelder, D; Kahimba, F.C; Korodjouma, O; Abebe, A; Oughton, E; Bunclark, L; Lasage, R
The objective of this paper was to examine farmer-directed technology adaptation of selected water harvesting technologies (WHTs) in order to enhance their potential contribution to food security and livelihood improvement in sub-Saharan Africa. The selected WHTs included micro- and meso-scale reservoirs that store water in the soil (in situ) or in a reservoir, respectively: household ponds in Ethiopia, ndiva systems in Tanzania and combinations of mechanized zaï, grass strips and bunds in Burkina Faso. The impact of non-adapted WHTs was below expectation. Although WHTs improved yields, most families were unable to meet their (nutritional) food needs every year and experienced limited or no long-term effects on sustainable livelihood. The lining of household ponds and conveyance canals with durable materials gave promising results, yet needs economic consideration; a minimum investment may form a barrier particularly to resource-poor farmers. Incorporation of the location-specific nature of farming and livelihoods into WHT interventions is recommended, along with incentive measures to support farmers including the provision of access to credits and inputs for agricultural production.
Adaption of the traditional coffee pulping machine to soybean dehulling
(2008-06) Silayo, V.C.K.; Laswai, H.S.; Ballegu, W.R.W; Mpagalile, J.J.; Kulwa, K.; Yuda, B.
Processing of soybean for human consumption requires wet heat treatment of the beans in order to inactivate anti-nutritional factors. After hot water treatment or steaming, dehulling of the bean has always been an uphill task for household processors in Tanzania. Dehulling is done by hand rubbing, which is tedious and time consuming. The traditional coffee pulping machine was adapted to dehull boiled soybean. Seven soybean varieties namely TGX-1876-2E, Bossier, Kaleya, TGX 1805-8E, Sable, Songea and Duicker were tried. This was a development process whereby three consecutively improved versions of dehulling machines were tested. The machines were branded Ml, M2 and M3, implying first, second and third generation, respectively. Bean recovery as a measure of performance was 74.3, 77.4 and 91.8% for Ml, M2 and M3, respectively compared with 89.7% for manual dehullingfrubbing. The respective throughput was 8, 10 and 28.2 kg/h compared with 0.43 kg/h for manual dehulling. The mean dehulling efficiency of the M3 dehuller was 82.4% which was the highest. The M3 dehuller's best performance was due to use of ball bearings to support the rasping roller axle instead of sleeves and its ergonomically suitable height. The M3 dehuller could be adopted for soybean dehulling under rural livelihood conditions but the economics for owning and running it needs to be explored. Its improvement to make it moiorised is recommended to increase throughput and increase chances for adoption in medium scale soybean processing.
Adoption and scaling-up of conservation agriculture in Tanzania: Case of Arusha and Dodoma regions
(Scientific Research, 2014-02-21) Kahimba, F. C.; Mutabazi, K. D.; Tumbo, S. D.; Masuki, K. F.; Mbungu, W. B.
A study was conducted to assess the adoption and scaling-up of Conservation Agriculture in Arumeru district, Arusha region, northern Tanzania and Chamwino and Dodoma Urban districts in Dodoma region, Central Tanzania. The study employed structured questionnaire survey and key informant interviews as the main data collection methods. Data analysis was done descriptively to determine factors that influence the adoption. Results showed that farmers in Arusha have highly adopted terraces, minimum tillage and cover cropping whereas their counterparts in Dodoma have highly adopted large planting pits, minimum tillage, and rippers. The intensity of adoption in Arusha is higher for the wealthy compared to the poor while in Dodoma the wealth status was not a factor that influenced adoption of the Conservation Agriculture (CA) technologies. The process of technology adoption should include the use of various participatory methods including farmer field schools, experimental plots, farmer exchange visits, and training of trainers among others. Use of farmer groups, incentives, and support instruments such as Savings and Credit Co-operative Society (SACCOS) or warehouse receipts systems are also important to ensure that farmers realize some acceptable profits from their efforts. Involvement of various stakeholders is also very important including local governments and agricultural change agents at national, regional, district, ward and village levels. Hence, the intention to promote CA technologies should not only look at the economic importance, but also its socio-economic importance to the local people in the area. Their desire to adopt and out-scale a technology should be among the most important investment factors that the government and development partners should consider.
Agricultural drought analysis for sustainable smallholder maize production in semi-arid areas: A case study of the lower Moshi irrigation scheme, Tanzania
(2015) Patrick, B.; Kimaro, D.; Lal, R.
Rainfed maize (Zea mays) in semi-arid Sub-Saharan Africa is subject to many climate-related risks—including agricultural dry spells and droughts. Effectively selecting appropriate agricultural water management strategies must first begin with evaluation of the potential climate-related risks. This article evaluates dry spell occurrence in the Mabogini Village—located within a semiarid area in Tanzania—using a water balance approach with nineteen years of historical daily precipitation data. The water balance equation was related to crop water requirements to evaluate both the prevalence of agricultural dry spells as well as estimate the water deficits throughout the same time period. Only four of the nineteen seasons did not experience a dry spell of at least five consecutive days. 37% of the seasons had at least one dry spell of 6-10 days while 63% had at least one dry spell of greater than 15 days. Soil water deficit in relation to crop production ranged from 0-140 mm. This study concludes that dry spells lasting greater than 15 days throughout 63% of the past 19 growing seasons represent a high risk to smallholder farmers in the area. The high prevalence of long dry spells suggests that rainfed maize production is not sustainable in the region without interventions. However, relatively small water deficits suggest that proper water capture, storage, and supplemental irrigation methods could help to bridge the gap between dry spells. It is therefore recommended that water management practices be put in place immediately to support productive and sustainable maize production in the area.
Agriculture is the main driver of deforestation in Tanzania
(Environmental Research Letters, 2020-02-26) Doggart, N.; Morgan-Brown, T.; Lyimo, E.; Mbilinyi, B.; Meshack, C. K.; Sallu, S. M.; Spracklen, D. V.
Reducing deforestation can generate multiple economic, social and ecological benefits by safeguarding the climate and other ecosystem services provided by forests. Understanding the relative contribution of different drivers of deforestation is needed to guide policies seeking to maintain natural forest cover. We assessed 119 randomly selected plots from areas deforested between 2010 and 2017, in Tanzania. Through ground surveys and stakeholder interviews we assessed the proximate deforestation drivers at each point. Crop cultivation was the most commonly observed driver occurring in 89% of plots, compared to livestock grazing (69%) and charcoal (35%). There was evidence of fire in 77% of plots. Most deforestation events involved multiple drivers, with 83% of plots showing signs of two or more drivers. Stakeholder interviews identified agriculture as the primary deforestation driver in 81% of plots, substantially more than charcoal production (12%), timber harvesting (1%) and livestock (1%). Policy-makers in Tanzania have sought to reduce deforestation by reducing demand for charcoal. However, our work demonstrates that agriculture, not charcoal, is the main driver of deforestation in Tanzania. Beyond protected areas, there is no clear policy limiting the conversion of forests to agricultural land. Reducing deforestation in Tanzania requires greater inter-sectoral coordination between the agriculture, livestock, land, energy and forest sectors.
Analysis of Intra and Interseasonal Rainfall Variability and Its Effects on Pearl Millet Yield in a Semiarid Agroclimate: Significance of Scattered Fields and Tied Ridges
(Water, 2019-03) Silungwe, F.R; Graef, F; Bellingrath-Kimura, S.D; Tumbo, S.D; Kahimba, F.C; Lana, M.A
Establishing food security in sub-Saharan African countries requires a comprehensive and high resolution understanding of the driving factors of crop production. Poor soil and adverse climate conditions are among the major drivers of poor regional crop production. Drought and rainfall variability challenges are not fully being addressed by rainfed producers in semiarid areas. In this study, we analysed the spatiotemporal rainfall variability (STRV) and its effects on pearl millet yield using two seasons of data collected from 38 rain gauge stations scattered randomly in farm plots within a 1500 ha area of semiarid central Tanzania. The STRV effects on pearl millet yield under flat and tied ridge management were analysed. Our results show that seasonal rainfall can vary significantly for neighboring fields at distances of less than 200 m, which impacts yield. The STRV for daily rainfall was found to be more critical than for total seasonal rainfall amounts. Scattering fields can help farmers avoid total harvest loss by obtaining at least some yield from the areas that received adequate rain. The use of tied ridges is recommended to conserve soil moisture and improve yields more than flat cultivation in semiarid areas.
Application of self-organizing-maps technique in downscaling GCMs climate change projections for Same, Tanzania
(2010) Tumbo, S. D.; Mpeta, E.; Mbillinyi, B. P.; Kahimba, F. C.; Mahoo, H. F.; Tadross, M.
High resolution surface climate variables are required for end-users in climate change impact studies; however, information provided by Global Climate Models (GCMs) has a coarser resolution. Downscaling techniques such as that developed at the University of Cape Town, which is based on Self-Organizing Maps (SOMs) technique, can be used to downscale the coarse-scale GCM climate change projections into finer spatial resolutions; but that must be combined with verification. The SOM downscaling technique was employed to project rainfall and temperature changes for 2046-2065 and 2080-2100 periods for Same, Tanzania. This model was initially verified using downscaled NCEP reanalysis and observed climate data set between 1979 and 2004, and between NCEP reanalysis and GCM controls (1979 - 2000). After verification, the model was then used to downscale climate change projections of four GCMs for 2046-2065 (future-A) and 2080-2100 (future-B) periods. These projections were then used to compute changes in the climate variables by comparing future-A and B to the control period (1961-2000). Verification results indicated that the NCEP downscaled climate data compared well with the observed data. Also, comparison between NCEP downscaled and GCM downscaled showed that all the four GCM models (CGCM, CNRM, IPSL, and ECHAM) compared well with the NCEP downscaled temperature and rainfall data. Future projections (2046-2065) indicated 56 mm and 42 mm increase in seasonal total rainfall amounts for March-April-May (MAM) and October-November-December (OND) (23% and 26% increase), respectively; and a temperature increase of about 2°C for both seasons. Furthermore, it was found that during MAM there will be a decrease in dry spells by 2 days, and an increase in seasonal length by 8 days, while for OND, there will be also 2 days decrease in dry spells, and 40 days increase in the seasonal length. The results for future-B shows a 4°C rise in temperature, and 46.5% and 35.8% increase in rainfall for MAM and OND, respectively. The results imply a better climatic future for the area because of the increase in the amount of rainfall and decrease in dry spells. However, it is suggested that further investigations are required to see if the projected changes will have real positive effects in agricultural production and also identify better agronomic practices that will take advantage of the opportunities.
Assessing the Impacts of Land Use and Land Cover Changes on Hydrology of the Mbarali River Sub-Catchment. The Case of Upper Great Ruaha Sub-Basin, Tanzania.
(Scientific Research Publishing Inc., 2018) Mutayoba, E; Kashaigili, J.J; Kahimba, F.C; Mbungu, W; Chilagane, N.A
Intensification of agricultural land use and population growth from 1990-2017 has caused changes in land cover and land use of the Mbarali River sub-catchment which is located in the Upper Great Ruaha Sub basin, Tanzania. This has affected the magnitude of the surface runoff, total water yield and the groundwater flow. This study assesses the impacts of the land cover and land use changes on the stream flows and hydrological water balance components (surface runoff, water yield, percolation and actual evapotranspiration). The land use and land cover (LULC) maps for three window period snapshots, 1990, 2006 and 2017 were created from Landsat TM and OLI_TIRS with the help of QGIS version 2.6. Supervised classification was used to generate LULC maps using the Maximum Likelihood Algorithm and Kappa statistics for assessment of accuracy. SWAT was set up and run to simulate stream flows and hydrological water balance components. The assessment of the impacts of land use and land cover changes on stream flows and hydrological water balance component was performed by comparing hydrological parameters simulated by SWAT using land use scenarios of 2006 and 2017 against the baseline land use scenario of 1990. Accuracy of LULC classification was good with Kappa statistics ranging between 0.9 and 0.99. There was a drastic increase in areal coverage of cultivated land, for periods 1990-2006 (5.84%) and 2006-2017 (12.05%) compared to other LULC. During 2006 and 2017 surface runoff increased by 4% and 9% respectively; however, water yield increased by only 0.5% compared to 1990 baseline period. This was attributed to increased proportion of cultivated land in the sub-catchment which has a high curve number (59.60) that indicates a higher runoff response and low infiltration rate.
Assessment of annual utilization rates of farm tractors in Mbarali district, Tanzania
(Sokoine University of Agriculture, 2015) Lwesha, Emmanuel Mjobege
The study was conducted in Mbarali District of Mbeya Region with the objective of assessing the average annual utilization rates of farm tractors for both on-farm and off- farm activities during the cropping season of 2012/13. The study conducted aimed at addressing the following research questions: who are the owners of farm tractors in the study area, what models were in use and what were the available support services that could enhance sustainable utilization of tractors? Questionnaire and a log–book were the instruments used for data collection for this study. A total of one hundred and eleven (111) farm tractors were involved in this study, of which 90 were power tillers [or 2 wheel tractors (2WT)] and 21 were conventional tractors or 4 wheel tractors (4WT)]. Results obtained show that all conventional tractors were privately owned and 94.6% of the power tillers were privately owned with the remaining 5.4% being owned by farmer’s groups. The age of the tractor owners ranged from 31 to 50 years old and all were able to read and write. Siam Kubota and Amec power tillers were the most popular 2WT in the area. The average annual utilization rates of 4WT was 1093 hours and 627 hours 2WT. Results of annual utilization rates of farm tractors in Mbarali District conclude that both conventional tractors and power tillers are optimally utilized. The study has also revealed that there are many dealers of tractors and spare parts in the District. Most repairs of farm tractors were performed by local mechanics in their respective villages; this therefore ensuring the long term sustainability of utilization tractors in the District.
Assessment of environmental degradation in Nakambala Mazabuka Zambia
(Sokoine University of Agriculture, 1996) Chinjila, Mellon Halubanje
An environmental degradation assessment was carried out in Nakambala Estate, Mazabuka Zambia in October 1994 to June 1995 . The objectives of the study were: impact change, of the natural sugar plantation vegetation between 1970 and 1993 ; (b) and (a) on demographic resource degradation expansion land to assess the to assess the soil physical and chemical status in cultivated and abandoned areas; and (c) to compare current soil physical and chemical status of the study area with the status when the sugar plantation was being established. Sequential aerial photography was used in assessing sugar plantation expansion and its impact on natural vegetation and land resource degradation. The impact of the sugar plantation expansion on demographic changes and energy needs (fuelwood) was also assessed. A field soil survey was carried out to assess soil condition in terms of general fertility and selected land qualities and characteristics matched with the requirements of irrigated sugarcane using the FAO (1983) land suitability framework. Soil carried out by using indices. degradation assessment wasiii The results of the study were; the sugar plantation expanded by 7 035 ha between 1970 and 1991; human population increased by 4 929 (at 4% per annum) and projected to reach 22 127 by the year 2 000. to sugar Natural vegetation was reduced by 25 % due plantation expansion aggravating the fuelwood deficit situation (5 447 m3/year in 1970 and 4 906 m3/year in 1991) . There was no visible evidence of soil erosion although waterlogging was the prevalent form of land degradation in all the mapping units. The soils are generally eutric (base saturation > 50%) with slight acidic to neutral reaction in cultivated fields (in mapping units; 2W, 10, 11 and 12) to slightly alkaline reaction in areas with abandoned fields (soil mapping unit 13). High soil bulk densities occur in soil mapping unit 2W due to compaction by heavy machinery and due to inherent nature of the soils in mapping units 10, 11, 12 and 13 (heavy clays). Oxygen inavailability (due to poor drainage), physical degradation and poor rooting conditions (due to shallow effective soil depth) are the most limiting conditions for sugarcane changes in chemical status growing. Over time, noticeable (sodication) was low in all the mapping units except in unit 10 where sodication development was noticed. Adverse soil physical changes (crusting and surface sealing) occurred in soil mapping units 11, 13. 12 andiv To stem environmental deforestation, degradation in the form of energy utilization from fuelwood should be reduced by electrifying township housing units. The continued use of vetiva grass for drain protection is advised. Alternative land uses in soil mapping units 11, 12 and 13 and complete abandonment of monocropping practices in these soils is strongly recommended.
Assessment of improved ladder terraces in controlling soil erosion on Uluguru Mountains-Tanzania
(Canadian Center of Science and Education, 2016-06-15) Materu, S. T.
This study assesses effectiveness of improved ladder terraces in controlling soil erosion on steep slopes of Uluguru Mountains in Morogoro Region, where runoff collection tanks were located downstream of the divisor system were all runoff from the catchment upstream where improved ladder terraces were located. The soil properties percentage weight for sand, silt and clay were average 40, 10 and 50 respectively. Half of the terraces were left barely and half were planted with maize crop. Runoff and soil loss generated during every rainstorm was collected from six field plots of improved ladder terraces to the tanks. There was statistically significant different between reductions of soil loss in bare improved ladder terrace and cropped improved ladder terrace. The amount of runoff on the bare soil was high by 15% to 18% compare to runoff on cropped soils. It was found that cropped improved ladder terrace reduced soil loss by 74% while bare improved ladder terrace reduced soil loss only by 41%. Simple linear regression shows runoff water generated from rainfall amount with soil losses from different land cover. Bare soils behave with linear relationship (r² = 0.85) unlike cropped soil were r² = 0.36 because of gradual increase of crop canopy at every crop stage hence less impact to the soil. Soils losses from the bare soil ladder terrace and that of cropped soil ladder terrace was significantly difference with correlation coefficient of 0.863 at vegetative stage and 0.928 at the full booting stage.
Assessment of processing methods, sensory attributes, nutritional quality and safety of cassava leaves product (isombe) in Rwanda.
(Sokoine University of Agriculture., 2014) Umuhozariho, Marie Goretti
Cassava (Manihot esculenta Cranz) leaves are cherished as a vegetable in Africa, but contain a toxic compound, cyanide. Studies were conducted to assess utilization, cyanide and nutritional value of cassava leaves after different preparation procedures in Rwanda. After a survey, leaves from bitter, sweet and wild cassava were: (1) pounded and cooked, (2) dried, pounded and cooked, and (3) pounded, dried and cooked. Drying was done to brittleness in a solar dryer after leaves were blanched. Sensory evaluation was done using a five point hedonic scale, where 5= like very much, 4= like moderately, 3= neither like nor dislike, 2= dislike moderately and 1= dislike very much. Cyanogens, vitamin C, P- carotene, crude protein, iron, calcium, phosphorus, potassium, zinc and moisture content (dry weight basis) were determined in: (i) un-dried, (ii) dried, (iii) un-dried and cooked, and (iv) dried and cooked. Tire chemicals of dry stored samples were also monitored after three, six, nine and twelve months. Results showed that cassava leaves from the three species were consumed as food and sun-drying was a single method used by fanners to extend the storage life. Colour, taste, aroma, texture and overall acceptability were principally affected by processing procedures. Fresh and dry leaves were preferred as vegetable except when they were pounded after drying. After boiling for 30 minutes. cyanide level (40 mg HCN/kg) was above FAO/WHO recommendation (10 mg HCN equivalent/kg) in the relish, but was judged as safe for the fact that it is served in small quantities as side food, reducing the HCN by serving to minor levels in comparison to documented acute oral lethal dose of HCN for an adult (30-210 HCN/60 kg bodyweight). Except vitamin C, amounts of P-carotene, iron, calcium, phosphorus, potassium and zinc were considerable, averaging 340, 153,4264, 3531, 8426 and 54 mg/kg, respectively, and protein (34%) was high and valuable for cyanide human body detoxification. Stored, moisture increased significantly by 6.8% and shelf life was estimated at six months in water, air and light proof material. Further studies in Rwanda on cassava cyanide disorders and approximate safe quantities of cassava leaves relish are recommended.
Assessment of the Impacts of Climate Change on Hydrological Characteristics of the Mbarali River Sub Catchment Using High Resolution Climate Simulations from CORDEX Regional Climate Models
(Canadian Center of Science and Education, 2018) Mutayoba, E; Kashaigili, J.J; Kahimba, F.C; Mbungu, W; Chilagane, N.A
This study assesses the impacts of climate change on water resources over Mbarali River sub-catchment using high resolution climate simulations from the Coordinated Regional Climate Downscaling Experiment Regional Climate Models (CORDEX_RCMs). Daily rainfall, minimum and maximum temperatures for historical climate (1971-2000) and for the future climate projection (2011-2100) under two Representative Concentration Pathways RCP 8.5 and RCP 4.5 were used as input into the Soil and Water Assessment Tool (SWAT) hydrological model to simulate stream flows and water balance components for the Mbarali River sub-catchment. The impacts of climate change on hydrological conditions over Mbarali river catchment were assessed by comparing the mean values of stream flows and water balance components during the present (2011-2040), mid (2041-2070) and end (2071-2100) centuries with their respective mean values in the baseline (1971-2000) climate condition. The results of the study indicate that, in the future, under both RCP 4.5 and RCP 8.5 emission scenarios, the four main components that determine change in catchment water balance (rainfall, ground water recharge, evaporation and surface runoff) over Mbarali river catchment are projected to increase. While the stream flows are projected to decline in the future by 13.33% under RCP 4.5 and 13.67% under RCP 8.5 emission scenarios, it is important to note that simulated surface runoff under RCP8.5 emission scenario is higher than that which is obtained under the RCP4.5 emission scenario.
Assessment of upgrading strategies to improve regional food systems in Tanzania: Food processing, waste management and bioenergy, and income generation
(SAGE, 2015) Graef, F; Schneider, I; Fasse, A; Germer, J.U; Gevorgyan, E; Haule, F; Hoffmann, H; Kahimba, F.C; Kashaga, L; Kashaga, L; Lambert, C; Lana, M; Mahoo, H.F; Makoko, B; Mbaga, S.H; Mmbughu, A; Mmbughu, S; Mrosso, L; Mutabazi, K.D; Mwinuka, L; Ngazi, H; Nkonya, E; Said, S; Schaffert, A; Schäfer, M.P; Schindler, J; Sieber, S; Swamila, M; Welp, H.M; William, L; Yustas, Y.M
Food security is one of the main goals of rural poor people. To enhance food security in this context, participatory action research can help to ensure sustained success while considering entire food value chains (FVC). This paper assesses the feasibility and potential success of upgrading strategies (UPS) as well as their assessment criteria as developed by German and Tanzanian agricultural scientists. The results form part of a larger participatory research project conducted in two climatically representative regions of Tanzania: semi-arid Dodoma and subhumid Morogoro. This paper presents the findings with respect to food processing, waste management and bioenergy, along with income generation and market participation. Assessments on other components of the FVC, including natural resource management, crop production and consumption, are reported by Graef et al (2015). The assessments for food processing revealed preferences for preservation techniques, oil extraction processes and food storage devices for the semi-arid region. In contrast, in the subhumid region, the experts favoured food storage devices and preservation techniques. Assessments of waste management and bioenergy UPS for both regions indicated the importance of animal feed from crop residues, crop residues as mulch and compost from food waste, although with somewhat different priorities. Assessments on income generation and markets in both regions revealed preferences for savings and credit cooperatives and communication techniques, but also indicated that warehouse receipt systems and guarantee systems had a high impact. Assessments differed between the two different climatic regions, and to some extent also between the nationality of experts and their gender. The authors therefore attach importance to integrating different South–North and female–male awareness in assessments among scientists. Moreover, local and/or regional stakeholders and experts should be involved in developing site-adapted UPS for enhancing FVCs.
Assesssment of the Perfomance of sun drying of maize grains on perforated surfaces
(1998) Silayo, V.C.K.; Kajuna, S.T.A.R.; Omari, B.
Sun drying of maize grains on different mesh sizes ofperjorated trays using different heights from the ground was investigated. The mesh sizes used were 1.5 mm and 3 mm at the elevations of 30, 60 and 90 cm. The results show that both mesh size and height from the ground affect the drying rate and seed viability. The combination of90 cm elevation and 3mm mesh size gave the highest drying rates and lowest seed viability loss.
Cassava Sun Drying Performance on Various Surfaces and Drying Bed Depths
(2013) Silayo, V.C.K; Lazaro, E.L.; Yustas, Y.; Laswai, H.S.
Processing of cassava (Manihot esculenta Crantz) to obtain flour is faced with a lot of technical constraints including inefficient drying. The traditional sun drying method is very inefficient as the product can take 2- 3 days to dry. Mould growth and other problems such as contamination of the product are likely and therefore necessitate intervention. Among the interventions was sun drying on a platform raised 1 m above ground in comparison with drying in a direct box solar dryer; by using trays with various bottom surfaces. The experiments were done using kiroba cassava variety obtained from the University farm, which was peeled and sliced into thin chips (2-3 mm) then sun dried on wire mesh, black polythene, white polythene and woven mat for three days. The material was dried for 8 hours daily after which it was kept indoors overnight. The surface with highest sun drying performance was wire mesh while white polythene was the least. The 10 mm bed depth attained constant weight in just about six hours of drying while for 20 and 30 mm bed depth it was about 16 hours and 40 mm bed depth for about 24 hours. There was moisture adsorption which was at 10, 22 and 28 hours for the 10 mm bed depth, 10, 20, 26 and 28 hours for 20 and 30 mm bed depths, and 28 hours for the 40 mm bed depth. The time 0,10 and 20 hours marked the beginning of drying whereas 8, 18 and 28 hours marked the end of drying. The best performance was therefore obtained on wire mesh and 10 mm bed depth and recommended for sun drying of cassava. However; there is need to investigate on whether there is significant quality difference between cassava sun dried at different bed depths investigated in this study
Cassava sun drying performance onvarious surfaces and drying bed depths
(2013) Silayo, V.C.K; Lazaro, E.L.; Yustas, Y.; Laswai, H.S.
Processing of cassava (Manihot esculenta Crantz) to obtain flour is faced with a lot of technical constraints including inefficient drying. The traditional sun drying method is very inefficient as the product can take 2- 3 days to dry. Mould growth and other problems such as contamination of the product are likely and therefore necessitate intervention. Among the interventions was sun drying on a platform raised 1 m above ground in comparison with drying in a direct box solar dryer; by using trays with various bottom surfaces. The experiments were done using kiroba cassava variety obtained from the University farm, which was peeled and sliced into thin chips (2-3 mm) then sun dried on wire mesh, black polythene, white polythene and woven mat for three days. The material was dried for 8 hours daily after which it was kept indoors overnight. The surface with highest sun drying performance was wire mesh while white polythene was the least. The 10 mm bed depth attained constant weight in just about six hours of drying while for 20 and 30 mm bed depth it was about 16 hours and 40 mm bed depth for about 24 hours. There was moisture adsorption which was at 10, 22 and 28 hours for the 10 mm bed depth, 10, 20, 26 and 28 hours for 20 and 30 mm bed depths, and 28 hours for the 40 mm bed depth. The time 0,10 and 20 hours marked the beginning of drying whereas 8, 18 and 28 hours marked the end of drying. The best performance was therefore obtained on wire mesh and 10 mm bed depth and recommended for sun drying of cassava. However; there is need to investigate on whether there is significant quality difference between cassava sun dried at different bed depths investigated in this study.

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