Department of Engineering Sciences and Technology

Permanent URI for this communityhttp://10.10.97.169:4000/handle/123456789/21

Browse

Now showing 1 - 20 of 207

The Mechanics of a disc plough
(Sokoine University of Agriculture, 1985) Kiriama,L.L.
ABSTRACT An angle attachment was designed to enable disc axis orientation with the soil bin facility developed at the College.A force prediction model by Godwin et al at Silsoe College was used to predict the magnitude of forces to be expected.- The effect of change in axis angle on draught,- vertical and side forces was studied and the results compared with the prediction. It was found that there.was a significant effect in changing the disc axis angle, The draught and side forces were found to be less at 15° than at 0^ 0° axis angle, angle. The optimum axis angle at 25° sweep was found to be about 15 o ’where the maximum downward vertical force occured. Since the experimental and predicted results did not compare well, an exploration of the force prediction model was suggested.Whilst for global prediction the model seemed alright,it was difficult to make it work for all combinations. Although the model worked well with an 0° axis angle and 90° sweep angle, the edge effect and inclination for the other combinations needed greater definition.
Plant-water status and grain yield of maize (zea mays l) in relation to soil water status at Morogoro, Tanzania.
(Sokoine University of Agriculture, 1987) Rwehumbiza,Filbert Bartazar Rwabulala
Analysis was made of reference crop evapotranspiration (Eto) and rainfall (R) data on a 10-day basis over a 10-year period (1973/74 - 1982/83).On the average, ETo exceeds R during the entire short rain season thus making production of crops other than those tolerant to water stress a risky undertaking.The effects of soil water holding capacity (WHC), cultivars,and water regimes on soil ~ and plant - water status, growth, grain yield and yield components of maize (Zea mays L) were identified.The study was conducted during short rains on two soils (both Ferralsols) one x
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%.
Auger metering studies for fine prilled URSA
(Sokoine University of Agriculture, 1988) Mwombeki, Francis Fabian
ABSTRACT Tne performance of sheet ana 'wire au6ers was studied for meterin6 prilleu urea fertilizer. First the physical characteristics of prilled urea was established. It was found that the angle of repose and the coefficient of fricition on galvanized steel surface increased with increased moisture content.The opening of the hopper bottom, inclination of hooper walls and modes of agitation were studied for uiiximizing fertilizer flow into the metering chamber. A bottom opening width of jO mm, hopper wall angle of 60 o with the horizontal and a rotary or eliptical agitation modes aere founu to provide optimum flow.Succeeding experiments were conducted to study the rate and consistency of fertilizer metering by sheet and wire auoer unaer varying pitch/diameter ratio,delivery tube in .ination, au6er speed and fertilizer moisture.Rate of fertilizer injection into flooded soils was studied under simuxared field conditions. Assessment was also made of the amount of r.-rti 1 i zer adhering to the augers during metering. A pitch diameter ratio of 1.25 give a maximum found to diecharge. Also, fertilizer discharge increased with greater inclination of the delivery tube and decreased with increasing fertilizer moisture contents.The metering accuracy generally decreased with greater inclination of the delivery tube fertilizer granule size decreased metering accuracy.The experiments, of injecting fertilizer in flooded soils were conducted in a rotating soil bin to simulate actual field conditions.The inclination of the delivery tube along the direction of the bin movement gave a higher injection rate than an inclination against the bin movement. The wire auger exhibited a greater injection capability than the sheet auger and produced higher pressure at the tube opening.This auger also encountered less sticking of fertilizer on the flight than the sheet auger.
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 and repair initial and depreciation age,maintenance costs purchase price and relation expressed tractor between cumulative as a percentage, of cumulative depreciation against tractor age and resale value to its annual operating cost against tractor age. Multiple regression computer software in the MSTATC version facility package was used to test the 1 .41 models. Important empirical relations were derived from the results of the tests. Qualitative factors were the investigated quantities shown to influence 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 similar given the future substitutive models. found to defy prices of or The trend of actual depreciation was basic the depreciation models. Purchase assumptions of accounting It was demonstrated that due to high inflation rates it is not possible to assign terminal salvage values to tractors notwi thstandi ng.in good running order, their age not with standi ng.
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
Sprinkler perfomance evaluation at Mtibwa Sugar Estates
(Sokoine University of Agriculture, 1994) Emmanuel,Marealle
ABSTRACT A perfomance evaluation study aimed at evaluating Mtibwa sprinkler irrigation system was carried out at Mtibwa sugar estates,Morogoro. The specific objectives were:(1)To investigate whether the application rate,duration of application and operating pressure of the current system meet the sugar cane water reqirement with respect to the prevailing soil moisture deficit.(2) To investigate sprinkler irrigation performance parameters whether the system is operating as designed and give recommendatons in relation to low yield difference between irrigated and rainfed cane.The results showed that about 20 % of all sprinkler irrigated blocks had coefficient of uniformity below 80 %.The pressure recorded ranged from 1.8 to 3.2 bar and 73 % of all blocks had sprinklers operating below the designed pressure of 3.2 bar.From the performance parameters the study showed that about 38 % of all blocks required longer duration of irrigation than the current practiced one. The longer required duration per set is identified to be due to low application rate which is also caused by low operating pressure at the pump stations and consequently to the sprinklers. Therefore,the low yield and insignificant yield differences between irrigated and rainfed sugar cane is caused by poor performance of the sprinkler system.This led to inadequate application of water.
Sustainability of irrigation schemes for small scale farmers: a case study of furrow irrigation scheme at Buleya Malima, Gwembe Valley Zambia.
(Sokoine University of Agriculture, 1995) Masinja,Rusmus
This study was carried out to determine factors that influence sustainability of smallholder irrigation schemes in Zambia.This was against background the that many schemes have been opened by the government to resettle people and have operated smoothly under its management. But upon government withdrawal, farmers have failed to manage these schemes. The study was carried out at Buleya Malima smallholder irrigation scheme.The objectives of study were; (a) to evaluate the schemes using technical and socio-economic parameters inherent current practices in the scheme, and, (c) improving the performance assess the to make recommendations for of the (b)scheme to and management practices. The average results for technical study were: 26.4%, 64.5% and 9.2% for application efficiency, tailwater ratio and deep percolation ratio respectively. The results revealed thSustainability of irrigation schemes for small at there was a waste of water by farmers through tailwater runoff. Thus, the system was performing poorly, and could not be sustained at these levels of water loss.The study on socio economic revealed that irrigated farming could be sustainable if properly designed and planned with the involvement of the farmers. The big problem was lack of managerial ability innovativeness and by the scheme management to provide farmers with enabling environment to form their own viable organisations which could see the continuity of the scheme even after the government had withdrawn. Farmer Participation in planning,decision-making and implementation of these decisions is advisable in order to sustain the scheme operations. Enabling environment for Management should create farmers to form viable associations through which farmers and management would co ordinate their operations. Formal and informal training in technical operations of irrigation infrastructure and new agricultural practices should be provided, so that farmers are able to operate the irrigation system with minimum dependence on management trained management Therefore, personnel to provision of well impart appropriate knowledge on the operations and maintenance of irrigation system is advisable.
Evaluation of sprinkler irrigation performance at Simunye Sugar Estate in Swaziland.
(Sokoine University of Agriculture, 1995) Magongo,Bongani Harmon
The performance the evaluated study irrigation system at Simunye,objectiveswere:parameters,(1)To identify the original parameters,(2)To investigate performance parameters,whether the system is operating as designed,and (3)To recommend suitable changes in the operation and system configurations that could be implemented to improve the irrigation efficiency. The results showed that there were no available design parameters on which the system of Simunye Sugar Estate was designed. The system showed a uniformity coefficient (Cu)of 76%,which is within recommended Cu range for design market acceptance.The Distribution uniformity obtained was 61% and the potential application efficiency for the low-quarter (PELQ) was found to be 54%.Both of these parameters were lower than the recommended ones, and they were significantly different when compared with the recommended ones of at least 67% and 75-85%, respectively.The actual application efficiency for the lower-quarter (AELQ) was found to be 45% which is too low when compared to the PELQ.The minimum basic infiltration rate of the soils irrigated by sprinkler system was 5 mm/h. Factors which contributed to the non-uniformity of the system were wind velocity and wind the direction operating pressure (which was too high or lower than the recommended one for the system), evaporation losses,and the sprinkler spacing. From the results it was shown that management of the irrigation system had an effect on the poor performance of the system.
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.
Technical and economic comparison of performance between farmer and government managed irrigation schemes in Tanzania: a case study of Kapunga irrigation project
(Sokoine University of Agriculture, 1996) Chemka, David Nyakamwe
This study compares the performance of government-managed irrigation schemes (GMIS) to farmer-managed irrigation schemes (FMIS) at Kapunga rice irrigation project in Mbeya region in Tanzania. The specific objectives were to evaluate: (i) organisational structure of the two systems; (ii) water management aspects of the two systems; productivity and Appropriate (iii) economic performance of the two systems. Indicators been have used to quantify performance of the two types of management of irrigation. Results of the study show that the farmer-managed scheme, performed better than the government-managed scheme in attaining scheme irrigation efficiency, productivity,economic, and productivity, irrigation scheme financial in profitability. Applicable indicators for the farmer-managed irrigation schemes are quantified as shown below. Those of the government-managed scheme are indicated in brackets. efficiency was 61% (29%) ;Its overall irrigation average productivity was 3.2 ton/ha (2.2 ton/ha); economic profitability: internal rate of return was 3.2% (5%), benefit/cost ratio 0.6 (0.14); while its financial profitability: internal rate of return was 3.9% (5.1%), benefit/cost ratio 0.6 (0.13). The organisation of both the government and farmer-managed irrigation schemes were appropriate, however, both schemes were weak in irrigation management as the essential operation and maintenance activities were not carried out effectively. Schemes Both the government and the farmer-managed had canal maintenance problem. There was corresponding big error in water adequacy of 86% and 98% respectively arising from improper water control at the secondary canals offtake.Paddy nurseries in the government-managed scheme had undesirable water stress. However, both schemes were able to distribute water equitably, reliably, as well as maintaining a correct field water depth from tillering to flowering and grain formation stages.
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.
The effects of rainfall and catchment characteristics on runoff yield in semi-arid areas of Tanzania
(Sokoine University of Agriculture, 1996) Ojesi,Samson Oscar Frackson
A complete randomised block design three replications (viz :at 6%,experiment with (CRDB) and 15% 18% slope) was conducted in Kisangara, Tanzania from November, 1994 to May,1995. The experiment consisted of catchment length (viz: 6 m and soil surface cover treatments and 12 m) (viz:natural vegetation and bare-and-compacted) . The study period covered two rainy seasons, short rainy season (locally known as Vuli) and rainy long of objectives season the study Masika). (locallyknown wereinvestigate to as The effects of rainfall and catchment characteristics on runoff yield and to use the data obtained to develop and test an empirical model for semi-arid conditions of Tanzania.Runoff yield from 60 m2 (10 m x 6 m) and 120 m2 (10 m x 12 m) catchments was measured using a runoff collecting system.Rainfall, soil particle size distribution, soil moisture, infiltration rate and soil bulk density for the catchments were also monitored throughout the two rainy seasons. The results generated a showed that catchments at 18 percent slope significantly higher mean runoff yield than the catchments at 6 percent slope equal to or more than 6 mm. (p< 0.05) at rainfall amount similarly catchments at 15 percent slope generated a significantly higher mean runoff yield than catchments of 6 percent slope (p< 0.05) at a rainfall amount equal to or more than 6 mm. However, the mean runoff yield generated from catchments at both 15 and 18 percent was not significantly different (p< 0.05). The mean runoff yield per unit area of catchment was not significantly different from the 6 m and 12 m length catchments. However, the total mean runoff yield generated from the 6 m length catchments was 9 percent- more than the total mean runoff yield generated from the 12 m length catchments for the two rainy seasons studied. The mean runoff yield from bare and compacted catchments was significantly different from the mean runoff yield generated from natural vegetated catchments (p< 0.01).The mean runoff yield from bare and compacted catchments at 18 percent slope was highly correlated with the rainfall characteristics (r> 0.95).Overall correlation coefficient between mean observed and mean predicted runoff of the empirical model developed was high (0.84) indicating that the model is suitable for semi arid conditions of Tanzania and can reliably be used to predict runoff in areas where no such measurements are made to design harvesting. The optimal micro-catchments for rain water.
Effects of Mswiswi watershed degradation on stream flow in Usangu village irrigation project
(Sokoine University of Agriculture, 1997) Malongo,Gerald Wanda Sere
The effect of Mswiswi watershed degradation on stream flow was investigated as one of 5 watersheds used by Usangu Irrigation Project as source of water. The watershed was calibrated upon itself by establishing four watershed degradation scenarios as the basis for comparison of watershed degradation parameters and stream flow characteristics. The established degradation scenario were 1960-65, 1965-75, 1975- 86 and 1986-92. The 1960-65 degradation scenario was taken as the control period i.e the period for which watershed degradation was at the minimum level. Therefore all parameters of watershed degradation and stream flow of certain probabilities in 1960-65 were compared with the same parameters in other three scenarios.Watershed degradation evidence analyzed from aerial photographs of 1977 and 1992 shows that: watershed forest loss was 0.105 , 0.032 and 0.497 km2/year for mixed forest,forest reserve and low dense miombo woodland, respectively. Soil degradation through gully expansion was 0.049 km2/year.The study shows that precipitation in Mswiswi watershed is decreasing from 1963-1986. This has been evidenced by decreasing trend of 5-year moving averages of precipitation and precipitation of certain probabilities. Comparison of watershed degradation parameters in four degradation scenarios shows that there were a differences among scenarios as a result of degradation. There was a general decreasing trend of parameters such as watershed storage and watershed loss factor from degradation scenario of lower order (1960-65) to scenario of higher order (1986-92). This means that the trend of decrease in watershed degradation parameters was from 1963-1989. Watershed degradation parameters such as curve number and watershed degradation factor were, on the contrary, increasing from 1963-1989. The decrease of watershed loss and watershed storage indicate that watershed was degrading as has been evidenced by watershed forest loss. Similar indication of watershed degradation was shown by increase of curve number and watershed degradation factor. This study shows that there was a relationship between increasing trend of runoff and increasing or decreasing trend of watershed degradation parameter from one degradation scenario to another for a particular probability of exceedance. Runoff of 10 % probability was increasing from watershed degradation scenario of lower order to scenario of higher order as watershed storage and loss factor of the same probability was decreasing. The trend of changes in base flow of particular probability of exceedance was more related to the trend in which watershed degradation factor of the same probability was varying. Stream flow from Mswiswi watershed is affected by both climatic changes and watershed degradation. To evaluate the effect of watershed degradation alone, the developed runoff and base flow models were run for equal rainfall events, so as to see how the watershed in the process of degradation in different periods was responding or would respond to the same rainfall events. The results of model utilization show that runoff was increasing as the watershed was degrading for equal rainfall events. In the case of base flow, the results of model utilization show that watershed degradation was causing cyclic trends of base flow variability. The maximum and minimum base flow for equal rainfall were having recurrence intervals of ten years. The magnitude of maximum and minimum base flow was decreasing with time as watershed was degrading for equal rainfall events.
Farmers’ utility of irrigation water supply as a method of assessing irrigation system’s performance.
(Sokoine University of Agriculture, 1997) Makongoro, Elfariji Kohi
A model which employ Farmers’ Utility of Irrigation Water Supply (FUIWS) in assessing irrigation system’s performance has been developed in this study. The methodology was tested through a Case Study at Lower Moshi Farmer Managed Irrigation Scheme (Lower Moshi FMIS). The main objective was to investigate FUIWS as a method of assessing the performance of irrigation systems. Strong relationship was observed between Relative Water Supply (RWS) and FUIWS. Wherever RWS was high FUIWS was also high and vice versa as proved by positively large covariance value obtained. However, this relationship was identified as non linear correlation by significance correlation coefficient test. The graphs plotted showed relationship of the type: R = aen Where:R = RRWS in paddy fields. U' = UFUIWS. a and n are constants. In this particular Study, the scheme model obtained was: R = 0.377e,1,2SU Similar block models were established. The homogeneity test on the block mean values showed that; RWS have the same degree of variability for all levels of FUIWS. This indicated the ability of the scheme model to be used in place of block models. Different "a" and "n" constant values obtained between blocks indicated different irrigation management levels between blocks. The method was tested in paddy rice only, therefore more work is needed to test it in upland crops; traditional and improved Farmer Managed Irrigation Scheme (FMIS). Also, more research is required to establish whether threshold values "a" and "n" are universal or not and what factors influencing them.
Intervention measures and their effects on farmer managed irrigation schemes in Tanzania:a case study of Musa Mwinjanga irrigation scheme.
(Sokoine University of Agriculture, 1997) Omari,Juma Mzee
The study aimed at evaluating the effects emanating from intervention on farmer managed irrigation schemes (FMIS) was carried out at Musa Mwinjanga Irrigation scheme. The specific objectives were: (I) To evaluate the scheme rehabilitation status; (ii) To investigate the causes and magnitude of water losses; (iii) To evaluate water supply requirements; (iv) To assess and evaluate water management aspects of the system. Results showed that the scheme has been operating at low efficiency. The conveyance, distribution, application and project efficiencies were found to be 53.6%, 53%, 59.8% and 31.7% respectively. Low irrigation efficiencies have been attributed to high conveyance losses due to the pervious nature of volcanic soils and poor command of the canals. Most of the canals were found running below the field levels. Other reasons include high’operation losses due to poor water management practices; lack of water control facilities; and application losses arising from poor land levelling. The seasonal mean relative water supply (RWS) for plots varied between 0.96 and 2.92 due to inadequate irrigation scheduling and lack of flow measuring facilities. The overall seasonal mean RWS for the plots was found to be 1.83 with coefficient of variation of 0.354 and standard deviation of 0.647, indicating inequity of water distribution among the plots.T-test results of RWS within blocks showed no significant difference in adequacy of • supply at 5% significance level. This implies that farmers in sampled blocks were adequately irrigating at more or less equal proportion as per crops water requirements.Organisation of the scheme was found to be fairly appropriate. However, operation and maintenance activities are not timely, effectively and efficiently carried out.•Natural drainage and slopes within the scheme are not efficiently used and managed hence the waterlogging problems in lowland areas of the central part of the scheme. From the study, it is recommended that outstanding physical works left during phase-I should be accomplished. Damaged facilities should be repaired and farmers should be trained on proper water management aspects.
Use of landsat thematic mapper and ancillary data in assessing potential areas for rainwater harvesting cropping systems
(Sokoine University of Agriculture, 1997) Kweka,Amini Rabi
Rain Water Harvesting (RWH) is a system which can store and redistribute the moisture needed to enhance yields, in areas where rainfall distribution limit dryland crop production. In regions where rainfall is insufficient to produce’ even a minimum crop, water harvesting offers the potential to bring those areas under cultivation. However, in many areas,conventional planning data for selecting prospective sites for RWH cropping system is in most cases not easily available or not up to date. This study assess the possibility of using satellite images to improve and up-date the required data.This study used a nested procedure, combining a coverage of a small sample area by Landsat Thematic Mapper (TM) satellite imagery,conventional photo interpretation and analysis of soil and topographic maps to identify potential areas for RWH cropping system. Computer pattern recognition techniques were used to discriminate soil information from the Landsat Thematic Mapper (TM) satellite data on a sample area. Soil mapping units photo from a conventional soil survey and aerial interpretation were matched to the spectral map for interpretation and classified soil description of the generated classes. Field investigations were done to confirr the results of the sample area which was then extended to
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.
Relationship between the Angle of Repose and Angle of Internal Friction for Agricultural Granular Materials
(1998) Kajuna, S.T.A.R.; Rugenga, E.
The angles of repose and internal friction are important parameters which determine the flow characteristics of agricultural granular materials, such as flour, maize, beans, wheat, sorghum and rice. The angles have a big influence on the design offlow and storage structures of agricultural materials such as hoppers, silos, bunkers and bins because they determine whether the flow will be smooth or not, and whether the bursting forces in relation to vertical forces will be great or not. An apparatus for determination of the angle of repose was specifically designed for the purpose. The a'ngles of repose for three different grains, namely maize, sorghulll and rice at four moisture content levels, namely 10, 15, 20 and 25%wb were determined using the designed apparatus. A tri-axial compression machine was used to determine the angles of internal friction for the same grains and same moisture contents. The data obtained were fed into SAS statistical software for step-wise regression analysis. A model of the form r = 22.35 + 0.013<1> 2; + 0.019[MC] 2 where r = the angle of repose, 1 = angle of intemlilfriction and MC = percent moisture content on wet basis was established, and used to predict the angleofreposefor the tested grains ~ith high accuracy (R2 = 0.97). It was concluded that the angle of repose was consistently higher than the angle of internal friction for all the granular materials tested, and the angle of internal friction was highest for maize, followed by rice and finally sorghum.
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.

Browse

Browsing Department of Engineering Sciences and Technology by Issue Date