Theses and Dissertations Collection

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Evaluation of the UAC tool carrier used in maize production system
(Sokoine University of Agriculture, 1980) Kwiligwa, Emmanuel Makenzi Bundala
The Uyole Agricultural Centre (UAC) toolbar was developed to provide an effective animal drawn cultivation and planting device for use in low- rainfall farming systems and capable of manufacture by local artisans. This work describes an essential element of the development process for this toolbar viz its evaluation in practical maize production system. The evaluation was made in terms of capacity, labour requirement, draught force, costs and weed control compared with conventional methods. A split-plot design in randomized block of two replications was laid out. Main treatments included four tillage systems (hand hoe plus hand planting; mouldboard plough plus hand planting; UAC tool carrier tine plus hand planting and UAC tool carrier tine plus planter) while sub treatments included two weeding methods (hand weeding and UAC tool carrier weeder). The UAC tool carrier tine plus hand planting, and UAC tool carrier plus planter tillage treatments gave the lowest mean grain yields of maize. There was a significant difference at 1% probability level between tillage means. There was no significant difference between weeding means. The UAC tool carrier planter gave a lower plant population than hand planting. The UAC tool carrier was not effective as a weed control tool on uncultivated plots. It resulted into more weed shoot counts and weed dry weights. There was a correlation between maize grain yields per hectare and weed dry weight per hectare. The variance ratio was highly significant at 1% probability level showing a sufficiently good fit of regression relationship. The proposed UAC tool carrier system (direct drilling; 1st weeding by hand hoe on maize rows; requirement (46?4 of the purely labour input system) and increased the area cultivable per farm family. But 1st weeding by hand hoe on maize rows which was intended to be a quick operation was limiting. The proposed system also gave not only the lowest total costs of maize production per hectare but was one of the systems that gave the highest value of a day’s manpower. The draught force of the UAC tool carrier tine was lower than that of the mouldboard and ridger even when sweeps are attached on the former. The increase in rake angle did not have a remarkable change on the draught. The sweeps on the UAC tool carrier tine brought about more soil disturbance than without them although they increased the draught force. The unexpectedly high force to overcome rolling resistance was probably due to the size and weight of the UAC tool carrier.
Construction and evaluation of a modified multicrop thresher model IRR1-PAK
(Sokoine University of Agriculture, 1987) Kilasara,Wenceslaus George
A modified IRRI-PAK Multicrop Axial-flow thresher has been manufactured at the International Rice Research Institute (1RRI), Engineering workshop, based on the blueprints of the IRRI-PAK-30 Multicrop Axial-flow Thresher from Pakistan. The modifications include, a piece of hollow shaft to the threshing cylinder shaft; bolted thresher stands;increased area of one of the cleaning screens, and omission of locks and hinges on the observation windows. Different models of four-wheel tractors were used.Three of the four crops used —sorghum variety casor 2; paddy varieties IR38, IR58 and 1917; and yellow corn were obtained from IRRI experimental plots. Wheat was found in Ilocos Region - Northern part of the Philippines. Settings which included increasing/decreasing aspirator air vents, varying the slope/pitch of the oscillating tray assembly, and varying the cylinder speed/peripheral velocity were the variables for the experiments conducted. A conveyor was used during sorghum threshing,An output of 1594 kgh 1 with 97.65% cleaning efficiency, 98.47% threshing efficiency, 1.27% grain loss were recorded. The paddy threshed, gave an output range of UJ7kgh”1■l,r"'r'’-“1with cleaning efficiency of 93.39% 1569 kgh to 96.01%, and a threshing efficiency of above 99% and total grain loss of between 1.27% and 2.01%. The output of wheat varied from 790kghT1to 2110kgh cleaning efficiency of 76.60% to 96.57%. with Threshing efficiency increased with increased speed. The speed of 510rpm [17.81ms 1 ] gave 96.12% and 710rpm [24.79ms 1 ] gave 98.14%. The results for corn threshing were influenced by the concave bar clearance and or the design of the louvres which resulted to high grain losses from straw thrower (15.94% to 16.98%). The output ranged from 862 kgh -1 to 896 ,._^-lkgh withcleaning efficiency of 85.79% to 86.66% and threshing efficiency of above 99%.
Performance evaluation of rain water harvesting For paddy production in Tanzania
(Sokoine University of Agriculture, 1992) Mwakalila, Shadrack Sakai
The major problem inherent of the rain-water harvesting system for paddy production in North-West regions of Tanzania is low runoff efficiency and high rate of loss of stored water due to seepage and evaporation, which result in low yields and sometimes total crop failure. The present research was conducted in Shinyanga region with the objective of assessing the performance of the rain water harvesting system for paddy production. In order to achieve this objective the historical climatic and runoff data together with data from experimental runoff plots were analysed. From historical rainfall data the results showed that: -It is possible to receive 60mm of railfall within 24 hours once every two years and within wet season dry spells of unpredictable length and timing are common -The variations in yearly rainfall is some 25% over a period of 10 years. -At an annual rainfall of 800 mm water deficit in the paddies will amount to 1560 mm The experimental results showed that: -Uncompacted rain catchment with ground slope of less than 5% has an average surface runoff of 30^3 mm per month with mean runoff efficiency of less than 30%. -A compacted rain catchmet with ground slope of less than 5% has an average surface runoff of 66.4 mm per month with mean runoff efficiency between 45% and 60%. - Uncompacted rain catchment with ground slope greater than 5% has an average surface runoff of 66.4 mm per month with mean runoff efficiency between 50% and 65%. -A compacted rain catchment with ground slope of greater than 5% has an average surface runoff of 71.7 mm per month with mean runoff efficiency greater than 65%. -And also the study showed that most of catchments used are large areas of between 10 to 100 km' feeding runoff to ephemeral streams at a runoff yield efficiency of 12%. Therefore from the major findings it was concluded that the rain water harvesting system used in Tanzania has very wide potential but is currently inefficient, mainly due to the low control and inadequate management of the catchment area by the farmers. It is proposed that more research work is required to: quantify the yield benefits attributable to rain water harvesting; establish economically viable design parameters for catchments under different topographical and assess the erosion risks inherent of the system.
Assessment of the utilization, management and operating costs of agricultural tractors in the chemelil sugar belt in Kenya.
(Sokoine University of Agriculture, 1992) Onyango, Ogweno Samuel Roger
The research undertook to study the utilization, management and operating costs of agricultural tractors used in the Chemelil sugar belt in Western Kenya. Historical cost data spread over a span of 16 years were obtained for 141 tractors operated by three different owners in the belt. The data was used to assess the level of utilization and operating costs and to test mathematical models for predicting tractor resale values, repair and maintenance costs, annual operating costs as well as establishing the factors that influence them. It was found that tillage tractors in the belt had an average annual use of 1040 hours and transport tractors 1230 hours and that both category of tractors had restricted utilization due to limits imposed by maximum hectarage for tillage tractors and queuing discipline at the sugar factory and in the fields for cane transport tractors. Mathematical models were formulated and tested for relation between ratio of tractor resale value to its current purchase price and depreciation age, relation between cumulative repair and maintenance costs expressed as a percent of initial purchase price and tractor age, cumulative depreciation against tractor age and the ratio of tractor resale value to its annual operating cost against tractor age. Multiple regression facility in the MSTATC version 1.41 computer software package was used to test the models. Important empirical relations were derived from the results of the tests. Qualitative factors were shown to influence the investigated quantities quantitatively and that the control of the qualitative factors could reduce operating costs. A relation for predicting annual operating costs of a tractor basing on its replacement value was found. The relation could also be used to predict the tractor’s optimal replacement point given the future purchase prices of similar or substitutive models. The trend of actual depreciation was found to defy the basic assumptions of accounting depreciation models. It was demonstrated that due to high inflation rates it is not possible to assign terminal salvage values to tractors in good running order, their age notwithstanding.
Prediction of modified class a pan evaporation using radiation, temperature and wind speed data
(Sokoine University of Agriculture, 1993) Luhanga, Joseph
A simple evaporation model relating pan evaporation (Ep) to shortwave solar radiation (RJ, mean daily temperature (T) and wind speed (W) developed for different climatic conditions was calibrated for the Malawi conditions. The objectives of the study were to examine the possibility of using the model to estimate pan evaporation where such data are missing either because no such readings are recorded or a very short record is available whose extension is sort for various purposes. The model was also examined for use in areas where no shortwave solar radiation is measured and also for the possibility of using the model to estimate reference evapotranspiration (ETO) for such areas. Three stations, Bvumbwe, Chitedze and Ngabu were used in this study. The stations represent different climatic conditions within Malawi. Five-day averages of pan evaporation, shortwave radiation, mean daily temperature and wind speed were computed from data collected by the Meteorological Department between 1985 and 1988 inclusive. Data for 1985 and 1986 were used to calibrate the models and the rest were used for validation. A statistical software package (MSTATC) was used to calibrate the models using regression techniques while a climate version of INSTANT package was used for computing Rs and ETO by the modified Penman equation as presented by Doorenbos and Pruitt (1977). The models calibrated from measured Rs were found to be adequate for the three stations used in the study. All the models estimated pan evaporation to within 6%. Models developed from R, computed from tables were found to be slightly superior to models developed from measured solar radiation in that the variables included accounted for an average of 75% and 66% of the variability in the response for Ngabu and Chitedze respectively, as opposed to 74% and 56% for measured R,, despite the fact that only one year of data was available for their calibration. Correlation coefficients between observed pan evaporation and computed evaporation were high. High correlation coefficients (r=95%) were also observed between reference evapotranspiration and evaporation computed from models derived from tabulated solar radiation indicating that computed evaporation represents ETO well. These results indicate that the model is suitable for the Malawian climatic conditions and can be used to estimate evaporation where no such measurements are made and also to estimate both missing pan evaporation and ET
Evaluation of rainfall interception models in a maize field
(Sokoine University of Agriculture, 1996) Simwanza, Hopeson Isaac
Rainfall interception is a component of effective rainfall and is an important component in agriculture because of the latter's use in irrigation and drainage projects. A rainfall interception study was carried out at Kabanana farm plot no. 2952 M, a peri urban area in Lusaka, Zambia. The objectives of the study were (a) to measure rainfall interception by maize crop growing in a freely drained soil and (b) to evaluate and validate the models developed to represent rainfall interception loss. Standard raingauges placed adjacent to the study area and beneath the canopy of the maize plant were used to measure rainfall amounts. Funnel like collars were used to measure stemflow. A planimeter was used to measure leaf area required for the calculation of leaf area index and the data from the nearby University of Zambia meteorological station was used to estimate crop evapotranspiration. The results of the study showed that the interception process by a maize plant brought about an interception loss of 10%. Interception loss without stemflow was 27.4% implying that 17.4% of the incident rainfall reached the ground by flowing down the stalk of the maize plant as stemflow. Of the four models tested the models developed by Merriam (1960) , Leonard (1965) and De Jong and Cameron (1979) did not represent the process of interception by a maize plant. The linear regression model adopted by Gash (1979) which is insensitive to canopy structure was 93% significant for a two sided t-test at 95% confidence interval. It is highly recommended that the models should be calibrated before being adopted and a model should be developed that includes among the usual measurable parameters, leaf area configuration and branching patterns.
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.
Land evaluation using FAO framework for rainfed crops: a case study of Liti-tengeru farm
(Sokoine University of Agriculture, 1996) Muya, Mahenye Nyamhanga Chacha
A detailed land evaluation by using the FAO (1976) Framework and resource survey for 380 ha was carried out at Tengeru Livestock Training Institute (LITI) farm. The major objectives of this study were: (a) to test the adaptability of the FAO (1976) Framework for land evaluation in the area for rainfed field crops, vegetables, perennial crops, and pastures; (b) to establish the land resources inventory of the LITI farm; and (c) to assess the land suitabilities and limitations of the major land units in the farm for different land uses. The concepts and principles in the FAO (1976) Framework were found to work well in this area. However, some of the methodologies and procedures outlined in the FAO (1984) guidelines had to be refined in order to match with the actual local conditions and crops performance. Different approaches from those proposed in the FAO (1984) guidelines were used for reliable assessment of moisture availability, temperature regime and soil erosion hazard. Three soil types, namely, Mollie Andosols, Eutric Fluvisols and Pellic Vertisols, were identified in the area according to the FAO-Unesco (1974, 1988) legend. These soils were mapped at a scale of 1:10 000. The land evaluation results indicated that the major limitations in all soils of the study area are: moisture availability for perennial crops and pastures; Nitrogen deficiency; and land degradation through soil erosion and /or soil compaction. The major limitations for using Mollie Andosols in land mapping unit 34B1 are: severe soil erosion hazard, and buried stones which may limit tillage by using tractors. This land unit is very fertile and highly suitable for pasture production. It is highly suitable for vegetable and other field crops considered if soil erosion is controlled. The Eutric Fluvisols represented in mapping land unit 14C1, are highly fertile and suitable for all crops and pastures considered. However, like other land units in this farm, supplementary irrigation is necessary for optimum yield of perennial crops and pastures. The Pellic Vertisols in land unit 11C2 is not suitable for banana , citrus and coffee production. It is currently not suitable for maize, sunflower, tomato, Siratro, and elephant grass. It is suitable for rhodes and buffel grass. It is marginally suitable for the rest of crops and pastures considered in this study. The major limitations in using this land unit are: unfavourable soil structure and texture; poor drainage; shallow soil depth; presence of toxic layer (CaCO3) below 75 cm; high Sodium level; and deficiency of major nutrient elements (N, P, K). Economic analysis showed that pasture seeds production gave the highest farm net income in the area. Other crops which are highly economically suitable are vegetables, banana, citrus, coffee, and pasture fodder production. Beans, sunflower, sorghum and maize are marginally suitable in terms of farm net income.
Effects of tillage induced soil physical and hydrological properties on the soil water balance and the growth of sorghum in the semi arid areas of Tanzania.
(Sokoine University of Agriculture, 1997) Chenjerayi, Guzha Alphonce
Conservation of soil water is an important management objective for crop production objective is thus imperative. The integrated effects of tillage-induced soil physical and hydrologic properties on soil water balance on a sandy loam soil were evaluated. The field experiment consisted of five tillage treatments, namely tied ridging (TR), no till (NT), disc plough (DP), strip catchment tillage (SCT), and hand hoe (HH). Data measured in the field included soil moisture content, bulk density, surface roughness, infiltration, surface runoff and evaporation. Infiltration rates and depths were higher for the tilled soils than the untilled soils. The DP treatment had the highest cumulative infiltration. TR had low cumulative infiltration not significantly different from the NT treatment. SCT and HH treatments had almost similar values for cumulative infiltration but less than DP. The Kostiakov (1932) and Phillip (1957) infiltration models were fitted to the infiltration data and gave good fit. Depression storage determined using Mitchell and Jones (1976) depth-storage model was highest in the TR treatment. The higher the surface roughness the greater the depression storage volume. Regression analysis showed that random roughness decreased exponentially with increase in rainfall. Tillage increased total porosity and the DP plots in the semi arid tropics. Identification of the best tillage methods to achieve thishad the highest values. However total porosity decreased with cumulative rainfall in all treatments. Evaporation experiment results showed that a more open tillage-induced surface structure increased evaporation losses particularly during the first stages of evaporation. This resulted in higher cumulative losses for the DP and HH tilled soils than the other treatments. It therefore appeared that the acclaimed beneficial "soil mulch" effect was masked by the initial higher evaporation losses from the tilled soils under the atmospheric evaporative demands of the study area. Mean separation of the measured soil moisture showed significantly higher levels of soil moisture in the TR plots than the other treatments. Higher soil moisture contents were associated with treatments having higher depression storage. Field measured surface runoff after each rain storm also showed marked differences between the treatments. The tied ridged plots had the least runoff while the NT plots recorded very high runoff losses. Saturated conductivities estimated using van Genutchen model were highest in the DP soils and lowest in the NT soils. Analysis of the pF curves revealed that tillage reduced available water content and the NT had the highest total available water among all the treatments.
Digital processing of landsat thematic mapper satellite data for land cover classification using statistical methods for accuracy assessment: a case study of Ngerengere watershed
(Sokoine University of Agriculture, 1998) Mahuha, Fares Enock
This study involved primarily digital image processing and interpretation land for classification . cover Part of Ngerengere watershed covering about 300 km2 was taken as a case study Land cover which relates to the type of feature present on the surface of the Earth of the study area was elaborated. The procedures involved were reconnaissance survey to acquire 'a priori' knowledge about the u n s u pe r v i s e d area, classi f icat ion, field work classification, for rectification and restoration, ground supervised truthing, image ultimately producing and a land cover map of Ngerengere watershed. ERDAS 7.5 was the remote sensing (RS) software applied. The elaborated accuracy, land using cover map statistical was assessed packages. foric.s Overall classification accuracy (OCA) was about 70% which was below the recommended minimum level of interpretation accuracy value of 85%. It was however, revealed that the low OCA was substantially attributed by low producer's accuracy for the class of built-up areas which was only 22%. Although the produced land cover map had relatively low OCA, it had agood correlation with the present land use and vegetation. Further statistical analysis, by use of KHAT (K) statistics gave a value of 0.65 which is above 0.5 and approaches 1.0, hence acceptance of the land cover map produced from thatiii classification as primary data for land use planning. It percentage of also indicated extent the which to correct values of an error matrix used are due to true agreement and not by chance agreement. Chi-square (X2)distribution to test the goodness of fit of the land cover map elaborated, concluded absence of significant difference between the obtained and recommended OCA at significance level reject of and hence absence of enough evidence to 0.01, the classification for various applications like proposal for land use planning. In order to come up with a sustainable land use planning of the area, category other data are required. needed its own ancillary Every land cover data which are site specific to come up with. a proposal or alternatives for land use planning of an area. For instance, agricultural lands and rangelands classes needed much more ancillary data due to their spectral similarity and inseparability characteristics revealed during this study. Finally it is recommended for continuation of the study so as to come up with a sustainable land use planning of an area because thereis a problem already and timely intervention is imperative operation for the betterment of future generation.
Modelling of “field-to-field” irrigation method in Paddy basins for efficient water management
(Sokoine University of Agriculture, 1998) Nkhoma Oscar S.
In rice fields the most common traditional irrigation method is field-to-field irrigation method, i.e. conveyance of water across a paddy basin bund through a simple weir or circular pipe to irrigate the next basin. In using the method, there is uncertainty as to when the //nth basin, in a cascade, will receive the water after the preceding basins have attained the required depths. The method has been recognized and is practiced in some schemes in the sub-Saharan Africa. The method is commonly practiced by rice farmers in water scarce conditions. A farmer is tempted to tap water available in the neighbouring basin which has received water when there is low flow in the canal The study to model field-to-field irrigation method in paddy basins was conducted at Kasitu Self-help irrigation scheme in Malawi. This system of irrigation is practiced at this scheme. Reservoir routing equation was adopted and used to develop irrigation water routing model for paddy basins in field-to-field irrigation method by incorporating the factors associated with paddy basins. The model was tested with data obtained from Kasitu Self-help irrigation scheme. The model showed high precision in predicting paddy basin water storage with given inflows and outflows in a specified time, hence it was able to predict closely the time of fill of a given depth in a paddy basin. The results from the statistical analysis of the observed and calculated changes in water storage (in depth units) using the method of analysis of variance (ANOVA) at 5% significant level showed no significant difference in 11 sets of data out of 15 sets of data. The study revealed that the factors which affect water storage in a paddy basin and hence time of fill includes the initial soil water content, surface water inflow, surface water outflow, vertical seepage and percolation through the basin base, horizontal seepage across the bunds with water loss through cracks and fissures, evapotranspiration, and rainfall. The time of fill of n basins in a cascade of paddy basins was obtained as the summation of the times of fill of each of the n basins. The distance of travel of the stream flow was taken as the summation of the longitudinal distances of each basin in the direction of flow to the water front. Basin storage, time of fill, and distance travelled by the water front are all dependent on stream size (inflow and outflow), basin size and the associated water losses. The study proved that water travel time and time of fill of a paddy basin is predictable by using the factors which affect water storage in paddy basins. The computer program developed reduces the many calculations involved in the process to simply entering the raw data or some processed data on choice, hence serve time. It also helps to eliminate some simple errors which may occur in the calculation process. It is recommended that the method be adopted in the design process of paddy should also serve as measuring devices for irrigation water basin irrigation systems. The weirs used in the method are recommended that they should also serve as measuring devices for irrigation water
Validation of soil water balance models for crop assessment and yield prediction under Tanzanian conditions
(Sokoine University of Agriculture, 1998) Ntella, Pythias Mwakajila
The information gathering for early warning and crop assessment in Tanzania is still based on physical inspection of standing crops in fields. The physical inspection is based on sown area, the state of crop development towards maturity, the prevailing and anticipated weather conditions (during and after) at the time of inspection and the extent of crop attack by pests and diseases. The process is subject to human error and it is also time consuming. Developments in computer simulation models may provide an efficient method for analysis of data for early warning and crop assessment. This study was aimed at validating Irrigation Scheduling Information System (IRSIS) and Crop Growth and Irrigation Scheduling Model (CRPSMW) which are soil water balance simulation models for crop assessment and prediction of grain yields. Five stations viz. Ilonga Agricultural Research and Training Center, Msimba Foundation Seed Farm, Selian Agricultural Research Institute, Arusha Foundation Seed Farm, and Tanzania Pesticides Research Institute were selected for this study. Input data for the models comprised of weather, crop and soil data. Weather data was of a 10 year duration where as for the crop data the record length varied from 3 to 10 years. The [RSIS mode appeared to over predict grain yield of maize, sorghum, and wheat. This could be attributed to the inadequacy of the model to accurately account for the runoff, a fact that was depicted in the model output whereby a portion of the excess rainfall was utilized by the crop for evapotranspiration purposes. On the other hand, the CRPSMW model results were not significantly different (P<0.05) from the actual grain yields simulated yields of maize, sorghum, wheat, and beans. The simulated grain yields for the different planting dates falling on or after the probable date for start of the growing season during the long rains for both Morogoro and Arusha were not significantly different (P<0.05) from the actual grain yield. Although there was a good agreement between the actual and the CRPSMW model simulated grain yields, it was observed that, mean values for predicted grain yields were consistently smaller than for actual grain yields. This could be attributed o lack of representative location specific input parameters required by the model. These results indicate that the subroutine in the ERSIS model that considers runoff is inadequate and needs to be reformulated and/or allowance should be given for calibration of the model with respect to the runoff component. From the results it can be concluded, that a subroutine which considers factors such as hill slope, rainfall, and catchment area in estimating surface runoff should be incorporated into the IRSIS model to take account of the effects of excessive water on crop yields. There is also a need to determine more representative location specific parameters required by the CRPSMW model and the influence of moisture stress on different growth stages and hence yields under tropical conditions in order to increase its accuracy in predicting grain yields.
Growth and yield performance of maize grown under supplementary irrigation from gully flow
(Sokoine Univesirty of Agriculture, 1999) Bakari, Amin Masud
A study was conducted to assess the growth and yield performance of maize grown under supplementary irrigation using gully flow from large external catchment during the 1997/98 short rainy season. Two fields each of 180m x 60m size were prepared. One of the fields was dominated by fine sandy loam soils (field Fl) and the other field was dominated by silty clay loam soils (field F2). Three water application treatments were applied to each field. The treatments were flat cultivation without water conservation or supplementary irrigation (FC), flat cultivation with water conservation but without supplementary irrigation (WC) and flat cultivation with water conservation and supplementary irrigation from gully flow (WCIR). Supplementary irrigation when applied to plots with water conservation was found to improve the depth of the effective rainfall. However when direct rainfall amount was higher than 40 mm, application of supplementary irrigation from gully flows resulted into wastage of large volumes of water through runoff and deep percolation. The effect of prolonged dry spells on soil moisture status was found to be reduced by supplementary irrigation, especially in soils having higher water holding capacity. Grain yields were 1.9 t/ha, 2.1 t/ha and 2.5 t/ha from treatments FC, WC and WCIR respectively in field Fl and 1.8 t/ha, 2.5 t/ha and 2.7t/ha from treatments FC, WC and WCIR respectively in field F2. Biomass yields were 6.7t/ha, 6.0t/ha and 5.6t/ha from treatments WCIR, WC and FC respectively in field Fl and 7.4t/ha, 6.0t/ha and 4.2t/ha from treatments WCIR, WC and FC respectively in field F2. In field Fl, both biomass and grain yields from all treatments were not significantly different while foriii field F2 both biomass and grain yields from treatments WCIR were significantly higher than those from treatment FC at p = 0.05. It was concluded that whereas much runoff from marginal lands of the semi arid areas is wasted through gully flows, crop growth and yields can be improved when gully flow is used to supplement crop water needs in a field with water conservation in place. However, better results will depend on the water holding capacity of the soils. Further, care must be made to avoid excessive application of water on cropped fields during heavy rains. Finally it is recommended that this study be extended for several seasons to obtain enough data which will enable to establish a field manual to be used by farmers in their fields.
Determination of humidity-referenced potential areas for crop production in Tanzania
(Sokoine University of Agriculture, 1999) Mande, Ikingu Juma Mohammed
The study sought determine the potential area for production of maize,sorghum,groundnuts and beans based humidity levels. The specific objectives to on were; determine monthly humidity grades of the meteorological stations,to demarcate humidity zones,to establish potential for cultivation of the crops and to compare the established with those where selected crops are currently grown. Rainfall and evapotranspiration data of 97 stations were collected from the Directorate of Meteorology while the maximum water holding capacity,the growing periods and the crop coefficients of the selected crops were estimated from those available in the literature. Data analysis was based on hydrologic budget balancing model for stations and the computer packages; Microsoft Excel for windows 95 Version 7.0 and QUATRO PRO Version 4.00 were applied for determination for of humidity levels. Potential areas were delimited by grouping of stations of the same humidity levels. The areas were then compared those under current production. The study found that the approach seems to provide basic-information on potentials and and therefore be used for agricultural planning purposes. A fairly large percentage of areas established through this method ,especially for maize and sorghum, coincide with the current production areas. Among the three crops beans have shown the greatest potential over the country's total area and only 20% of it is utilized while groundnuts have the highest percentage of its potential area being unutilized. Recommendations from the study include: Mapping out of crop potentials related other factors to improve the predictability of the methods for agricultural planning Similar studies on specific crops be carried out in small areas and later to be combined to cover the whole country. Zonal research centres be involved to establish more meteorological stations so that each portion of the country is well covered.
Modelling and measurement of soil moisture content based on a remote sensing method for applications in Semi-arid tropics.
(University of Bonn, 1999-06-18) Salim, Baanda A.
Soil moisture plays a very crucial role in land surface processes It should therefore be monitored with the same accuracy and frequency as other important environmental variables Two approaches are used for estimation of soil moisture content, namely, modelling and measurement, either in-situ or remote. Integration of modelling and measurements may provide the best solution towards estimation of soil moisture content The utility of ground-based thermal infrared remote sensing method for the estimation of nearsurface soil water content was tested under tropical semi-arid agricultural conditions in Morogoro, Tanzania, East Africa Field experiments were conducted between January and August, 1997 at a bare soil site Regression relationships between the daily maximum surface soil temperature minus air temperature (TDMax) and weighted-average soil water contents to different depths in the soil profile were developed based on the measured data Better correlations were obtained for the top 0-5 and 0-15 cm layers of the soil, with coefficients of determination ofO 81 and 0.78, respectively Use of "Normalized TDMax" as well as cloudncsscover- correctcd "Normalized TDMax” (TDaMax) resulted in even better coefficients of determination (c g , 0 95 for the 5 cm depth) A physically based model of coupled flow of heat and water in the soil (SUAHEAT) was developed The SUAHEAT model was tested by comparing its simulated soil water contents and soil temperatures with those measured at the bare soil site Both qualitative as well as quantitative methods were used to evaluate the model performance, for the calibration and validation phases For the calibration phase, the average values of the mean absolute difference (MAD) of soil water content were 0.06, 0 05, 0 05, and 0.03 m7nP for the 5, 15, 30, and 45 cm depths, respectively The corresponding average values of the root mean square difference (RMSD) of soil water content were 0.07, 0 06. 0 05, and 0 03 m’/m’ for the same depths, respectively As for the validation phase, the average MAD values of soil water content were 0 09, 0.05, 0 08, and 0 17 nP/nP for the same depths, respectively. The corresponding average RMSD values for the same depths were 0 12. 0 08, 0 10, and 0 19 nP/nP, respectively The unusually large errors (at the 45 cm depth) during the validation phase could be attributed to the overestimation of soil water content values during very wet conditions arising from the calibration equation used. The performance of the model in the simulation of surface, near-surface, and profile soil temperatures was also both qualitatively and quantitatively evaluated In the calibration phase, the MAD values were 2 8, 1 1,0 5, and 0 3 °C for the 5, 15. 30, and 45 cm depths, respectively. The corresponding RMSD values for the same depths were 3 5, 1.3, 0.6, and 0.4 °C, respectively. For the validation phase, the MAD values for the same depths were 2.3, 1 2, 0 7, and 0.4 °C, respectively. The corresponding RMSD values for the same depths were 2.7, 1.4, 0.8, and 0.5 °C, respectively. Generally, the errors obtained with the use of the SUAHEAT model are comparable to values obtained by other researchers elsewhere using similar models. Integration of the model with remotely sensed surface soil water content and temperature data was effected through use of the initial profiles of soil water content and temperature. The initial profile data were derived from the regression relationships between TDMax and surface soil water content on the one hand, and between the surface and profile soil temperatures on the other, respectively. Model simulation results obtained using the remotely sensed initial conditions indicated that it is feasible to use remotely sensed data (one value of TDMax per day) to initialize the model Similarly, extrapolation of the remotely sensed near-surface (0-5 cm depth) soil water content to values at greater depths in the soil profile was shown to be feasible.
Effects of irrigation water on infiltration rate and saturated hydraulic conductivity in onion fields; a case study of ruaha mbuyuni irrigation scheme, iringa- Tanzania.
(Sokoine University of Agriculture, 2000) Nnko, Awariywa M.
A study was conducted at Ruaha Mbuyuni farmers7 managed irrigation scheme in Iringa region to assess the effect of irrigation water on infiltration rate and hydraulic conductivity and corresponding crop (onion) performance. The study involved assessment of water quality and soil properties in relation to infiltration rate and hydraulic conductivity problems, crop (onion) water requirement at different stages and its performance under different soil types. The results indicate that water from Lukosi river was low salinity and low sodium water. Chemically, this water have slight effect on infiltration rate and hydraulic conductivity. The concentration of suspended sediments were high where about 25.54 t/ha 一 42.15 t/ha of sediment were deposited in the fields over the season. This resulted into sealing and clogging of soil pores hence reducing infiltration and hydraulic conductivity. The soil texture in the scheme ranged between sandy loam to heavy cracking clays and they are neither saline nor sodic. The soils are slightly alkaline with pH ranging from 7.4 to 7.8. The organic matter content were generally very low ranging from 1.13% to 3.05%. Due to the low organic matter content, the soils had poor structural stability and hence easily dispersed when water is applied. Dispersion effects resulted into reduction of infiltration rate and hydraulic conductivity. Soil basic infiltration rate ranged from 3.75 mm/h to 52.5 mm/h while saturated hydraulic conductivity ranged from 0.03123 m/d to 0.4236 m/d for clay and sandy loam soils respectively. Basic infiltration rate decreased for an average of 50% while hydraulic conductivity decreased for an average of 52% - 58% over the season in all soils. High deposition of sediment and high dispersion effect of irrigation water on the soils were the main reasons for decreased infiltration rate and hydraulic conductivity over the season. The crop (onion) performance was generally low in all locations compared to the normal yield of 35-45 t/ha and 8-10 Kg/m3 fbr yield per unit area and specific yield respectively. Medium textured soils which had moderate infiltration and hydraulic conductivity had better yield of 31.5t/ha while coarse texture soils with rapid infiltration showed very poor yield of 13.3t/ha. Clay soils had better specific yield of 5Kg/m3 while sand soils showed low specific yield of 3Kg/m3. Low infiltration rates and hydraulic conductivity resulted in water logging problems in the heavy textured soils. Rapid infiltration in the course textured soils caused water stress to crops and drain of plant nutrient below root zone which contributed to low yields. It was observed that the water application depended on the available irrigation water and not on crop water requirement. Relative water supply (RWS) ranged from 0.92 to 5.36 per crop development stage. Irrigation intervals which were far spaced was the main reason fbr excess water application during irrigation. It was concluded that water from Lukosi river has good quality and can be used fbr irrigation in all types of soils with slight reduction of infiltration rate and hydraulic conductivity.
Investigation of quality of service IP routing algorithm
(University of Essex, 2003) Mwaipaja, Ivan
Internet communication is mainly determined by how best datagrams1 are routed from source machine to destination machine. Routing is done in the network layer of the OSI/RM by special machines called routers. Using proper protocols2 routers can compute a path over which a datagram has to follow to reach the desired destination. One of the protocols most commonly used in routers is the OSPF. This protocol implements an algorithm called Dijkstra’s algorithm3 in computation of the relevant path to destination for an incoming datagram. Basically Dijkstra’s algorithm uses only shortest paths to calculate routes; i.e. the algorithm will return shortest possible routes from a source router to all other routers in a network4. Dijkstra’s algorithm does not consider the quality of service required by the individual datagrams; as long as they are destined to the same router they will all follow the same path. Hence, there is a need to have an algorithm that will take into account the QoS required by the individual packets. One of the algorithms that consider QoS is- that described in [1], In this project, the above mentioned algorithms will be simulated by writing Java computer program(s). Emphasis will be on investigating the QoS IP routing algorithm. The results of the two algorithms for different network conditions will be analysed and compared. A well GUI will be implemented to better illustrate the algorithms for the benefit of many users. Finally, comments and conclusion will be drawn on how best the QoS IP routing algorithm can replace the existing Dijkstra’s algorithm.
The potential for rainwater harvesting
(Sokoine University of Agriculture, 2004) Kazuzuru, Benedicto
Rainwater harvest has become one of the strategies by the Tanzanian government in fighting the persistent drought in the country. The government awareness of the importance and use of the rainwater harvest has been facilitated by the joint team of experts from the Sokoine University of Agriculture and the University of Newcastle working to develop a model of the rainwater harvest (RWH) process as an aid to identifying best-bet options The joint team of experts from the two universities has developed a computer program to support their work on rainwater harvest. This is called PARCHED-THIRST, which is an acronym for, Predicting Arable Resource Capture in Hostile Environments During The Harvesting of Incident Rainfall in Semi-arid Tropics). Among its key functions, PARCHED THIRST simulates agrometeorological variables for use as inputs in the simulation of crop growth. This project assesses the simulation of climatic variables,rainfall and temperature in particular. The project looks at the, flexibility of the PT software and the methodology used in the simulation. The data used for analysis is from Arusha (1970-2000) in Tanzania, which has been supplied within the software. This site has longest records of climatic data among the sites whose data is supplied within the software. An exploration of the data indicates that, the PT models the means (monthly, weekly, yearly) effectively but underestimate the spread of the data. The analysis of the rainfall data indicates that higher order Markov chains are needed at the site in Tanzania as this leads to an improvement in modelling the spread of the data. For the temperature data, the assumption of first order autoregressive process was found to be valid, but the assumed stationerity of the correlations did not hold. The flexibility of the PT software has generally been found to be good, following updates by the PT team at Sokoine University over the last three years. However the software needs to be further modified to suit the varied needs of its intended customers.
Water availability and use dynamics and the sustainability of water resources management in the great Ruaha river catchment in Tanzania
(2007) Rajabu, Kossa Ruzebelle Mnyimvua
The purpose of this study was to investigate sustainability of water resources management in the Upper Great Ruaha River Catchment (UGRRC) and the impacts of water availability and use dynamics to the downstream river flows. Trend analysis, regime shift analysis, low flow analysis and generation of indicators of hydrologic alteration (IHA) were among the methods used to investigate variability of rainfall and river flows. Water abstraction and use patterns were investigated through intensive hydrometric monitoring and social survey methods. An integrated river basin decision-making framework was developed and used to assess the sustainability of water resources management. The study found out that although river flows entering the UGRRC have not changed much between pre 1980 and post 1980 time windows, split sample analysis of the flows showed that the mean annual runoff exiting the UGRRC decreased from 2537.55 Mm 3 to 2053.77 Mm 3. The dry season flows also decreased by 57% between the two time windows and the decrease, found to be due to human interventions taking place in the plains, is statistically significance at 5% significance level. Analysis of IHA parameters revealed a progressive decline in flows lower than Q 30 . The analysis showed that 1-day minimum flow exiting the UGRRC decreased from 2.572 m 3 /s to 0.1221 m 3 /s; Q 90 decreased from 2.720 m 3 /s to 0.266 m 3 /s; zero flow days have increased from 0.25 days to 22 days per annum in the post-impact period; and the minimum flows now, start two weeks earlier as compared to the pre-impact window. This implies a faster depletion rate of dry season flows in the UGRRC.iii Comprehensive assessment of water demands and water resources of the Mkoji sub- catchment revealed that during the dry season water resources are the limiting production factors as they are not enough to meet the current requirements for irrigation, let alone other water use sectors. The formal water rights were found to be problematic as in eight out of the 12 studied river systems water rights were higher than the actual river flows. However, the granted formal water rights were much higher compared to the actual water requirements resulting into over-abstractions of water above what is needed for crop production. As such streams run dry half way through the sub catchment as water that would have kept them flowing throughout the year are used up for irrigation. The result is that downstream water users suffer more from water shortages and some sub-catchments (e.g. Mkoji) are now closed during the dry season, contributing zero flows to the Great Ruaha River. Assessment of sustainability showed that current water resources management practices in the UGRRC are unsustainable and if maintained, they could lead to severe social, environmental and economic consequences. The study concludes that there is a need to review the formal water rights to conform to current water availability and requirements and to improve monitoring and data management system in order to fulfil the mission, goals and objectives of water resources management in Tanzania. This study has demonstrated the value of combining different research methods and analyses and the role of simple decision support tools to assist in reaching and evaluating decisions concerning sustainable water resources management.
Potentials and constraints of Kilombero valley among agro pastoralists community
(Sokoine University of Agriculture, 2008) Luwanda, Paschal Lucas
Environment degradation, loss of grazing lands, high grazing intensities and drought in northern regions of Tanzania, led to massive migration of pastoralists and livestock to more resourced areas in the south. This has brought different ethnic groups into same ecological ranges there by increasing environmental degradation and resource use conflict. Kilombero valley is one area which received many pastoralists now days with highest conflict incidents reported. The objectives of this study were, (a) to identify major land uses in the valley (b) to evaluate selected land utilization types (c) to identify areas of land use conflicts and (d) to recommend remedial measures. Land unit map was established through visual aerial photo interpretation, three main physiographic units were distinguished: the Hilly, the Piedmont and the alluvial plain. PRA and questionnaire were used to collect socio-economic data and SPSS programme was used for analysis. Soil survey carried out and soil samples were analysed for physical and chemical properties important to the requirements of the selected land utilization types. The results revealed that, land uses in the valley include farming, grazing, bee keeping, wild life utilization, fishing and forest utilization. The absence of irrigation schemes, limited use of new agricultural technology, poor agricultural infrastructure and extension services are among the major constraints to farming. On livestock, overstocking and poor technical services are among the major problems. As for land evaluation, it was noted that the alluvial plain which potential for paddy cultivation, is in stiff competition with livestock grazing due to availability of pasture and water. Conflicts between farmers and pastoralists are rooted on crop damage by livestock and land disputes among others. Absence of exiting land use plan has worsened the situation. In conclusion, both pastoralists and farmers are engaged in farming and zoning for different land use types was recommended.iii

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