Theses and Dissertations Collection

Permanent URI for this collectionhttp://10.10.97.169:4000/handle/123456789/4412

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    Irrigation scheduling
    (Sokoine University of Agriculture, 1984) Thadei, Simon y
    This thesis deals with irrigation scheduling under rotational water supply. First, irrigation scheduling is defined and the general review of the principles, factors, methods, and scheduling techniques which must be considered before scheduling is given. This includes crop water requirements, factors affecting crop water requirements and methods for determining crop water requirements. Then soil waterholding capacity, irrigation requirements (efficiencies and leaching requirements), amount of water for irrigation, availability of water supply, and scheduling techniques are reviewed. Also, Tanzania's case study is given for two projects: Mbarali (a state farm) and Mombo (village owned farm). Finally, irrigation schedule is prepared for Mombo irrigation scheme.
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    Use of GIS and remote sensing techniques to evaluate the wetland degradation in the Wami Ruvu River Basin
    (Sokoine University of Agriculture, 2024-05) Kimario, Edina Pius
    Wetlands are crucial ecosystems that provide numerous ecological services, including water purification, flood control, and habitat for diverse plant and animal species. During the last decade, around 50% of the earth’s wetlands have already been converted to industrial, agricultural and residential use and these lands continue to disappear at a shocking rate without their values being understood. Wami Ruvu river basin in Tanzania is rich in wetlands, a total of 2482 km2 of the area is covered by wetlands both floods plain, marsh and swamp. Little information on wetland degradation on extent, condition, trend and drivers on wetland degradation is available Wami Ruvu river basin. However, the aim of the study was to assess Historical wetland degradation and prediction of future Wami-Ruvu Basin wetland change pattern. Multi-temporal Landsat satellite data including thematic Mapper Landsat (TM and ETM+) and Operational Land Imager (OLI) images were used for land use/cover (LULC) mapping in the assessment of wetland degradation and their distribution pattern based on the LULC by the years 2000, 2010 and 2020. A Random Forest Classification (RFC) approach was employed to classify the Landsat images into different land use/cover classes which included wetlands, water bodies, agriculture, urban areas, bush lands, bare lands, woodlands, and forest. The future wetland map of the study area was developed using hybrid CA- Markov in Land Cover modeler. The study observed the trend based on the spatial dynamics during the two decades Which showed a progressive decrease in the collection of wetlands coverage throughout the region, although the degradation rate varies in time coverage area as it was found to be about 1209.0753Km2, 949Km2, 521.33Km2 and 213Km2 of wetland was lost, for the year 2000, 2010, 2020 and 2050 for the individual pixel values respectively. On the other hand, the studies revealed that -34.41Km2/y of wetlands potentially are degraded annually due to human and natural stressors in 20 years of our study. Thus this gradual decrease in wetland area is contributed mainly by the increase of human activities within and surrounding the wetland boundaries which is well observed in classified land use/cover images with kappa statistics above 75%. The results of this study will contribute to a better understanding of wetland degradation in the Wami-Ruvu River Basin and facilitate informed decision-making for wetland conservation and restoration efforts. The findings will help identify priority areas for targeted interventions and provide a baseline for monitoring future changes in wetland condition and trend to attain the Sustainable Development Goals.
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    Modelling the water balance of a small catchment: a case study of Muhu catchment in Southern highlands of Tanzania
    (Sokoine University of Agriculture, 2000) T. Shiba, Sipho Simeon S.
    I'he water balance ol'Muhu catchment located in the Southern Highlands of Tanzania in Iringa region was modelled by establishing the empirical relations that exist between storage parameters, rainfall parameters and runoff components. Storage parameters included soil moisture storage and interception. Rainfall parameters included rainfall amount, intensity, duration. throughfalL stemflow and evaporation. Runoff components included total runoff, direct runoff and base How. The catchment's physical and hydrological characteristics that affect these parameters were determined. 1 he assessment of hydrological and physical properties showed that the soils were predominantly sandy clay, having high organic matter content, with a moderately rapid hydraulic conductivity (Ks) of 4.2 cm/h and infiltration rale of 3.8 cm/ h. The bulk density was generally low with an average of 0.9 g/cnT for 0-15 cm depth: 1.1 Ig/cm5 for 15-30 cm depth and 1.30 g/cm’ for 30 - 45 cm depth. The catchment had a slope steepness of 35 % and a varying vegetal percentage cover of about 56 %. The 1997/98 waler year was exceptional with high rainfall (1934 mm) mainly due to the El-nino phenomenon. Sixty-seven percent of the rainfall received in the catchment penetrated the canopy to reach the forest floor as throughfalL On average 3.3 % of the rainfall reached the forest floor as stem flow' while 25.5% of the rainfall was intercepted by the canopy. ThroughfalL stemflow and interception were linearlyIll related to rainfall. Die regression coefficients of all the relationships were significantly different from zero al 1% level (fteO). With increasing percentage surface cover, interception increased while throughfall decreased. The storage capacity of the forest cover was estimated to be 0.7 mm. Il has been found in this study that stream flow and runoff have gradually been increasing since the 1994/95 season. However the rainfall trend docs not support this development. A consideration of runoff curve numbers showed that the observed trend was partly due to catchment degradation, farming activities in the area have gradually been substituting the forest with arable land, thus reducing surface cover. Records indicated that the lowest recorded daily mean How was 0.27 m'/s. while the highest was 1.6 m'/s. I he water balance was positive during the first five months of the wet season. The highest water balance was in April. During this period there was more recharge to the soil moisture and ground water storage. Water balance was negative in the remaining seven months of the water year, with the lowest in September. The developed direct runoff model and water balance model were found to be valid and useful in estimating the respective parameters in forested catchments of the southern highlands of Tanzania.
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    Performance evaluation of an indigenous irrigation system at towero village, western Uluguru mountains, Tanzania
    (Sokoine University of Agriculture, 2000) Kongola, Malongo John Mussa
    Indigenous irrigation methods in mountainous areas are a result of people’s efforts to survive on limited land resource bases. The adoption of an irrigation method depends on whether it does not affect the soil. While surface methods are common in the Uluguru Mountains, drag hose sprinkling is receiving wide use at Towero. Drag hose sprinkler irrigation refers to the local use of sprinklers where water pressure is obtained by gravity flow. Effects of indigenous irrigation systems’ practices on soil erosion were evaluated using field data and aerial photographs. Field data were obtained from six slopes, ranging from 6 to 84%. Two versions of aerial photographs were used to produce land-use maps for 1964 and 1992, respectively. Traversing produced the land-use map of 1999. Land-use analysis revealed that between 1964 and 1999, the area under indigenous irrigation increased by 0.81 ha/ycar. Between 1964 and 1999 the settlement area increased by 0.83 ha/year. Deforestation rate was 6.48 ha/year. Mean crop yields for leeks ranged between 9.65 — 13.53 tonne/ha. Mean specific yields ranged between 0.65 - 1.09 kg/m3. Mean water conveyance, application and storage efficiencies were 83.72%, 86.20% and 99.64%, respectively. All fields wereii over-irrigated based on soil moisture data which were taken daily. Over-irrigation caused inequitable water distribution. Daily sediment load transport in canals A, B and C were 22.2 kg, 187.6 kg and 54.7 kg, respectively. Total sediment loss was 264.6 kg per day. Net downslope splash loss at 84, 70, 65, 24 and 15% slope was 28.9, 19.1, 12.0, 6.0, and 1.0 kg/ha, respectively. The effects of indigenous irrigation systems’ practices at Towero were: soil loss in the form of splash erosion and sediment load transport, and acceleration of deforestation in pursuit for more agricultural land. Hence, efforts to promote soil conservation practices at Towero are essential.
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    Mechanisms of mechanical oil expression from rapeseed and cashew.
    (University College Dublin, 1979-02) Mrema, Geoffrey C.
    The conventional theory of oil expression from vegetable oilseeds suggests that before substantial oil expression can occur, the oilseed cellwalls have to be ruptured by a combination of physical (crushing) and thermal (cooking) pre-treatments. Results from oil expression tests using rapeseed and cashew on the Instron Universal Testing Machine have suggested an alternative mechanism in which up to 80% oil is expressed through a porous cellular microstructure under pressure without cellwall rupture and at ambient temperature. The porous mission electron microscopy. The cellwall pores (plasmodesmata) were of diameter 0.87 and 0.126 pm wall surface area for rapeseed and cashew respectively. The oil expression process has been successfully described by a mathematical model based on three modified form of Terr.aghi's equation for the consolidation of saturated soils., to describe the behaviour of the consolidating oilseed cakej the Hagen Poiseulle equation for flow of fluids to describe the flow of oil through the pores on the cellwall; and The model has Darcy 's law of flow of fluids through porous media to describe the flow of oil through the intra-kernel voids. in pipes, fundamental equations: a oil expression can occur, the oilseed cellwalls and average porosity of 0.093 and 0.171% of the cellnature of the cellwalls has been confirmed by trans been succeafully applied to experimental data which has revealed that the flow of oil across cellwalls in the seed kernel was the rate determining step. In addition the model was also used to analyse the performance of hydraulic and screw expellers. The study has suggested that the design of both hydraulic and screw expellers could be improved by incorporating an undrained compression pretreatment to rupture cellwalls 3 and by reducing the drainage area to 0.5% - 1.5%. Furthermore^ improved strategies for oil expression have been suggested in two cases, (a) For mechanical expression followed by solvent extraction it is proposed that the physical (pre-crushing) and thermal (cooking) pre-treatments be replaced by an undrained compression pre-treatment. are not r equired (b) where mechanical expression is the sole process^ the pre-crushing pre-treatment should replaced by an undrained compression pre-treatment.
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    Repair costs of tractors and comparison of mechanization strategies under Tanzanian conditions
    (University of Munich, 2000-08) Mpanduji, Sylvester Michael
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    Design of the improved evaporative cooling structure for storage of tomatoes in morogoro
    (Sokoine university of agriculture, 2022) Mwankemwa, Leonard Saimon
    In most developing countries, smallholder farmers face several challenges while embarking on their farming for agriculture crop production. The challenges are serious during post-harvesting processes. The phenomenon is evident in sub-Saharan countries, Tanzania inclusive. Tanzania’s economy is agriculturally based which contributes 26.7% of its GDP and it employs over 80% of the population. As such any efforts geared to eradicate poverty and improve livelihoods should focus on the agriculture (horticulture subsector) which is characterized by small scale subsistent farming, low productivity, and huge post-harvest losses. These huge losses can be attributed to a lack of appropriate post- harvest processing techniques, low awareness, on the part of good harvesting and packaging practices or techniques and lack of storage facilities. Morogoro smallholder farmers of tomatoes are not spared from this phenomenon. Several storage technologies for curbing tomato post-harvest losses have been introduced to smallholder farmers. Some technologies have shown promising results. However, more investigation of the technology’s effectiveness is needed. This study aimed to design an evaporative cooling structure for the storage of tomatoes. A need assessment survey was conducted to help generate information on tomato handling practices and losses for small scale farmers and retailers in six selected areas in the Morogoro region. Sixty respondents with at least 3 years of farming or retailing tomatoes were purposively selected through the help of the extension officer and market leaders to represent part of the tomatoes’ handling chain. The findings obtained showed that farmers were not using any storage facilities for tomatoes while retailers used inferior handling facilities and some did not use any storage facilities, ultimately losing most of their tomatoes. This study found that tomato post-harvest losses (PHLs) were 29.7% at the farmers’ level and 18.4% at the small scale retailers’ level during handling and marketing. The majority of the respondents showed a desire to possess evaporative coolers to reduce tomato PHLs. In this context, the improved wind operated passive evaporative cooling (IWOPEC) storage structure for tomatoes was designed and fabricated, and its performance was evaluated against other storage conditions. A randomized complete block design (RCBD) was used. The storage environment conditions considered were ambient (AT), cold room (CR), and IWOPEC structure. The results on the effects of temperature and relative humidity (RH) were significantly different (p<0.05) under the studied storage environments. Total soluble solids and percentage weight loss significantly increased (p<0.05) for all studied environmental conditions, whereas firmness and titratable acid significantly decreased (p<0.05) in response to storage time and environmental conditions. The IWOPEC structure reduced temperature, increased RH and gave peak and daily average cooling efficiency of 84.89% and 61.67%, respectively. The result of the benefit-cost ratio (BCR) was 2.51 shows using the IWOPEC structure for the storage of fresh ripened tomatoes is viable. In areas with high PHLs under AT, using the IWOPEC structure to improve the shelf life of tomatoes is economically feasible. Improvement of the IWOPEC structure by having water boot sump and a water pump to increase the cooling efficiency of the storage atmosphere is recommended.
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    Development and performance evaluation of solar greenhouse dryer with desiccant energy storage system for tomatoes
    (Sokoine University of Agriculture, 2021) Mbacho, Susan Andrew
    Tomato is one of the most important horticultural crops widely grown in the tropical East Africa countries. It is mostly used as vegetable recipe for food preparation at most homes or consumed raw as a salad. However, during the rainy season, tomato farmers experience widespread post-harvest losses due to insect and molds infestation. Also, during harvesting seasons, most markets in East Africa are flooded with the produce leading to over- supply against low demand resulting to heavy postharvest losses. Therefore, it is necessary to use appropriate drying technologies especially solar drying technology to reduce these losses. The use of solar drying technology is a good alternative solution to the problem of crop drying and especially the perishable tomato crop. Literature review show that most solar crop drying technologies developed for the past 50 years have very small loading capacity and cannot operate during the night. Therefore, in this study, we developed an integrated greenhouse solar dryer with Clay- CaCl 2 solid desiccant energy storage system. Solar greenhouse drying systems have an advantage over other solar drying systems because its structural simplicity combined with high loading capacity. In addition, they have relatively good thermal crop drying performance compared to most solar dryers. The system was tested under no-load and load conditions. The experimental study with no-load condition exhibited the mean collector temperature of 41.9 °C giving an average temperature rise of 14.7 °C (35%) above the ambient (27.2 °C) with an average R.H. value of 32.6% at the flow rate of 0.28 m 3 /s on the test date. When the desiccant energy storage was used during night an average greenhouse temperature recorded within the drying chamber was 26.5 °C higher than the ambient temperature of 15.9 °C (40 % temperature rise). The results obtained under desiccant energy storage showed that at a 0.07 m 3 /s air flow rate with an average rise in temperature of about 13.6 (32.3%) against the average ambient temperature of 28.5°C. The average relative humidity within the system was found to be 36.5% lower than the ambient R.H. (84.1%). The collector efficiencies obtained from no load test was 46.2% and 40.8% for the dryer and desiccant chamber respectively. The performance of the dryer was evaluated with fresh tomato load during the month of September - December 2019 at Kenyatta University field site. The dryer demonstrated capacity to dry fresh tomatoes from 93.9% (wb) to 8.3% (wb) within 27 hours with solar greenhouse drying efficiency of 23% while at night the dryer demonstrated desiccant drying efficient of 19.9%. The drying rate for the two-day solar drying was 0.985 kg/h and 0.875 kg/h respectively and that in night drying using desiccants was 0.34 kg/h. The economic analysis of the drying system shows a payback period of less than a year (0.54 year) with benefit-cost ratio of 8.4 implying that the system is economically viable. On the basis of these results, it was concluded that prototype solar greenhouse dryer with Clay-CaCl 2 energy storage system has great potential for tomato drying and other high moisture agricultural products in East African countries.
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    Assessing potential land and surface water resources available and suitable for irrigated agriculture in the wami sub-basin Morogoro
    (Sokoine University of Agriculture, 2021) Malekela, Charles John
    Assessing potential land and water resources suitable for surface irrigation is essential for proper planning of their utilization types. The assessment has a great role in satisfying subsistence requirements, increasing agricultural production and hence reducing poverty. Despite efforts made by various stakeholders to improve agricultural productivity by increasing irrigated areas, Tanzania is still facing a daunting task of reaching the one million hectare target of irrigated area. This indicates that land and water resources are not presently effectively utilized. This study was initiated with the objective of assessing the land and water resources suitable for irrigated agriculture along with the extent of small-scale irrigation in the Wami sub-basin. Geographical Information System (GIS) based on Multi Criteria Decision Analysis (MCDA) was used along with various spatial tools including a model builder which was used to create geo-referenced maps of land and water resources. Ten layers (irrigation suitability factors) were used in the analysis for identification of potential land suitable for irrigated agriculture. Results indicate that, based on the suitability factors about 841.39 km 2 (3.11% of the total area), is highly suitable for surface irrigation, about 18,244.41 km 2 (67.51%), is moderately suitable and 7939.87 km 2 (29.38%), is marginally suitable for surface irrigation. Furthermore, results shows that the extent of small-scale irrigation is about 1958.87 km 2 . Moreover, results indicates that, approximately 1958 km 2 of land assumed to represent the extent of small- scale irrigated areas in Morogoro region including Dakawa and Mvomero in particular. As such, the exploration of various resources as observed in this study, including land, soil and water was well demonstrated by the integration of GIS-Based Multi Criteria Decision Analysis (MCDA), and the weighted overlay technique for land suitability analysis.
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    Root-zone soil moisture redistribution in cropping systems under freeze-thaw conditions
    (University of Manitoba, 2008) Kahimba, Frederick Cassian
    The availability and distribution of soil moisture within the root zone is a key factor in ensuring better crop growth performance and attaining improved yield. The soil moisture is influenced by farm management practices such as cover cropping that affect the freeze-thaw processes during the fall. This in turn may influence accumulation and redistribution of soil moisture during the winter, and thereafter, the soil’s response to thawing during spring, and availability of soil moisture for the subsequent season. The impact of cover cropping systems on soil temperature, infiltration, and soil moisture redistribution due to soil freezing and thawing was investigated. In addition, the effect of cover crop on the within-season and subsequent-season crop performance and yield was also investigated. Time Domain Reflectometry (TDR) and Neutron Scattering (NS) methods were used to measure the unfrozen and total water contents, respectively. Soil temperature was measured using thermocouples embedded in the soil profile. Soil moisture and soil temperature data were collected from August 2005 to September 2007. Laboratory calibration of the TDR miniprobes indicated the maximum cable length for the RG-58 50 Q coaxial cable to be 40.0 m when 35 mm TDR miniprobes were used. Since the TDR was found to overestimate the liquid water content at soil temperatures below 25°C, a method to correct the field measured TDR soil moisture for temperature effects was developed. During soil freeze-up, water from unfrozen soil layers below the freeze front migrated towards frozen layers above. Compared to non-cover crop treatment, the cover crop treatment did not freeze earlier during the fall, froze to a shallower depth during the i