Agricultural Engineering and Land Planning Collection

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Major factors influencing the occurrence of landslides in the northern slopes of the Uluguru mountains, Tanzania
(2000) Kilasara, M.; Mtakwa, P. W.; Poesen, J.; Deckers, J. N.
Landslide mitigation largely depends on the understanding of the nature of the factors that have direct bearing on the occurrence oflandslides. Identification of these factors is of paramount importance in setting out appropriate and strategic landslides control measures. The present study focused on the identification of the major factors influencing the occurrence oflandslides in the Northern slopes of the Uluguru Mountains, Tanzania. The main objective was to establish relationship between spatial distribution of landslides and their causative factors. Such information would enable the planning of appropriate and strategic control measures. Aerial photographs, field survey and Geographic Information System (GIS) techniques were employed to identify the landslides features which occurred during EL NINO rains, spatial distribution and their corresponding factors. The results show that landslides dominate the geomorphic units with slope gradient ranging from 25% to over 80%. The most affected geomorphic units are in the order: debris slopes> incisions and V-shaped valleys > amphitheatres. Factors which cause theoccurrence of landslides are both soil and terrain related. The most important soil characteristics are presence of shallow soil solum with low bulk density and high macro porosity overlying a relatively less porous saprolite or hard bed rock. The terrain related factors include: undercutting of slopes by roads and pathways and presence of very steep concave side slopes. Water flow from roads and pathways and seepage from irrigation channels are precursors for the triggering oflandslides in the study area.
Modelling the water balance of a small catchment: A case study of Muhu catchment in southern highlands of Tanzania
(Sokoine University of Agriculture, 2000) SHIBA, S1PHO SIMEON S. T.
I'he water balance ol'Muhu catchment located in the Southern Highlands of Tanzania in Iringa region was modelled by establishing the empirical relations that exist between storage parameters, rainfall parameters and runoff components. Storage parameters included soil moisture storage and interception. Rainfall parameters included rainfall amount, intensity, duration. throughfalL stemflow and evaporation. Runoff components included total runoff, direct runoff and base How. The catchment's physical and hydrological characteristics that affect these parameters were determined. 1 he assessment of hydrological and physical properties showed that the soils were predominantly sandy clay, having high organic matter content, with a moderately rapid hydraulic conductivity (Ks) of 4.2 cm/h and infiltration rale of 3.8 cm/ h. The bulk density was generally low with an average of 0.9 g/cnT for 0-15 cm depth: 1.1 Ig/cm5 for 15-30 cm depth and 1.30 g/cm’ for 30 - 45 cm depth. The catchment had a slope steepness of 35 % and a varying vegetal percentage cover of about 56 %. The 1997/98 waler year was exceptional with high rainfall (1934 mm) mainly due to the El-nino phenomenon. Sixty-seven percent of the rainfall received in the catchment penetrated the canopy to reach the forest floor as throughfalL On average 3.3 % of the rainfall reached the forest floor as stem flow' while 25.5% of the rainfall was intercepted by the canopy. ThroughfalL stemflow and interception were linearlyIll related to rainfall. Die regression coefficients of all the relationships were significantly different from zero al 1% level (fteO). With increasing percentage surface cover, interception increased while throughfall decreased. The storage capacity of the forest cover was estimated to be 0.7 mm.
Land suitability evaluation for the production of the major crops in the southwestern part of the Uluguru Mountains, Morogoro rural district, Tanzania
(Sokoine University of Agriculture, 2001) Kimaro, D. N.; Msanya, B. M.; Mwango, Sibaway, B.; Kimbi, Gerald, G.; Kileo, Emmanuel, P.
Land evaluation study was conducted on the southwestern slopes of the Uluguru Mountains in Morogoro Rural District, Tanzania to assess the potentials and constraints of the various land units for the production of low input rainfed cabbage, round potato and arabica coffee. The study area is located between latitudes 7 o 0000 and 7 o 1123.5S and longitudes 37 o 3000 and 37 o 3836.6E covering the villages of Kibaoni, Langali, Bunduki, Bumu, Kikeo, Luale, Mwarazi, Nyandira, Kibuko and Tchenzema. The areal extent is 419.64 km 2 (41,964 ha) with an average elevation ranging between 900 - 2700 m a.s.l. The mean annual rainfall in the study area ranges from 1065 mm to 2450 mm. The rainfall distribution pattern is monomodal with the rainy season starting from December to May. The peak rainfall occurs in April in most places of the study area. The high altitude areas receive more rainfall than the lower areas. In some areas rainfall distribution tends more to be bimodal with two peaks occurring in October and in April. There is considerable temperature variability in the study area with the mean monthly temperature ranging from 17.4 o C (July) to 22.4 o C (December). At high elevations temperatures are much cooler. The shortest reference length of growing period is 180 days while the longest is 270 days. The geology of the study area consists of a mixture of banded pyroxene granulites with occasional biotite-rich bands, foliated mica gneisses, hornblende gneisses and granulites and some iron-rich meta-anorthositic rocks, all belonging to the Usagaran system. In some places alluvial deposits and kaolinitic clays of Neogene age are found. The study area consists of strongly dissected mountains with very steep plateau and ridge slopes of about 30-60% and narrow valleys and incisions. Lukwangule plateau is the highest peak in the study area reaching an altitude of 2,623 m a.s.l. The Lukwangule plateau is only slightly dissected and the surface forms quite a mature relief. Two distinct drainage patterns exist in the study area. A sub-radial pattern which is related to the horse-shoe of high mountains from Mkumbaku through Lukwangule and Magari to Lupanga, which is currently represented by some of the larger rivers such as Mngazi, Mbakana and, in part, the Mgeta. A rectilinear pattern is exhibited where secondary streams and many main rivers show adjustment to geological structure and rock type. The pattern of the minor rivers follows the geological structure more closely and has resulted in river capture, reversed drainage and wind gaps. The edge of the meta-anorthosite is marked by the Mgeta, Mfunesi and Lukangazi river valleys for about two-thirds of its circumference, and this weakness is presumably the cause of the spiral course of the Mgeta River as it cuts back along the junction of rocks, capturing successively all the radial drainage from the north and west of the high level plateaux.
Short and medium term assessment of tillage erosion in the Uluguru Mountains, Tanzania
(Elsevier, 2004-05-26) Kimaro, D. N.; Deckers, J. A.; Poesen, J.; Kilasara, M.; Msanya, B. M.
Soil translocation due to shallow tillage by manual hoeing appears to be one of the most important erosion processes in the Uluguru Mountains. In order to quantify erosion rates caused by manual hoeing in the area a tillage experiment was set up and an on-farm survey was conducted during the dry season of the years 2000 and 2001, respectively. Soil flux rates on eight slope gradients (31–67%) were monitored by measuring the tillage step characteristics using Trapezoid-step method and by collecting soil material lost in Gerlarch troughs. Soil flux rates due to medium-term (30 years) manual hoeing along contour bands with grass barrier were also monitored by measuring volumes of tillage step below and colluvium accumulation above the surface of the original slope on six slope gradients (51, 52, 55, 56, 58 and 60%). Average tillage depth for superficial tillage was 5.2 cm. The results obtained by the Trapezoid-step method ranged from 43 to 70 kg m À1 per tillage pass with a mean tillage transport coefficient (k) of 107.5 kg m À1 on the tested slopes. Mean soil flux rates obtained by Gerlarch trough method were slightly lower than those obtained by Trapezoid-step method with values ranging from 14 to 77 kg m À1 per tillage pass and a tillage transport coefficient (k) of 83.9 kg m À1 per tillage pass. The rates measured by both methods showed an increasing soil flux with slope gradient. Results on soil flux rates due to the medium-term tillage operation (step measurements) showed a negative trend with increasing slope gradient. Soil flux ranged from 148 to 42 kg m À1 per year for slopes between 51 and 60%. Soil flux due to colluviation behind grass barriers showed a similar trend with values higher than those obtained by step measurements. The soil flux rates behind grass barriers ranged from 153 kg m À1 per year on slope of 51% to 67 kg m À1 per year on a 60% slope in approximately 30 years of cultivation. A reasonable correspondence between calculated displaced soil (area under original slope) and the accumulated colluvium (area above the original slope) was obtained indicating significant contribution of tillage erosion. Contribution due to water erosion processes ranged from 7 kg m À1 per year on slopes of 51% to 25 kg m À1 per year on a slope of 60%. The study demonstrated that tillage translocation rates due to manual superficial tillage are very high and could partly be held responsible for the development of shallow soils observed on steep slopes and the accumulation of colluvium behind grass barriers along contour bands in the Uluguru Mountains.
Untitled
(2004-12) Kimaro, D. N.; Msanya, B. M.; Kihupi, N. I.
A study covering an area of 358 km 2 was conducted at Wami Plains in Mvomero district, Tanzania to assess the suitability of land for various land use types with emphasis on smallholder low input rainfed maize, rice and extensive grazing. Expert knowledge captured in ALES computer programme was used to carry out physical and economic land suitability classification with respect to three major land utilisation types. Decision trees to assess the potentials and constraints of the land for the three land utilisation types were developed in ALES programme. Physical and economic land suitability classification and ALES predicted yields and gross margins are presented. The results indicate that about 90% of the area is physically moderately suitable and economically highly suitable for extensive grazing. Only about 43% is both physically and economically suitable for maize production and about 57% is either marginally suitable or not suitable for maize production. On the other hand about 57% of the studied area is marginally suitable for rice production while 43% is not both physically and economically suitable for this LUT. The most limiting factors for the production of the three studied LUTs are poor soil fertility, poor soil drainage conditions, tsetse flies and ticks infestation and soil erosion hazards. From this study it is also concluded that extensive grazing is economically more profitable in the area compared to the production of maize and rice. Basing on the current farmers observed and predicted yields there are high possibilities for obtaining higher yields from livestock under improved management levels. Maize production is recommended as the second important LUT in the area provided that soil fertility problems and poor drainage conditions are improved. Rice production is economically the third land utilisation type. Higher rice yields could be obtained if farmers were able to invest more on fertiliser use. This forms a strong base in favour of high investment in the area given the potential marketing possibilities in the expanding cities and towns in Tanzania and in East Africa.
Land use systems change and its influence on people’s livelihood in South Eastern Tanzania
(Sokoine University of Agriculture, 2006) Tenga, John Jasper
A study was carried out in South Eastern Tanzania to evaluate spatial and temporal changes that have occurred over a period of 40 years in land use systems and their influence on people’s livelihood. Field survey, remote sensing and GIS techniques were employed to assess land use systems dynamics. A questionnaire survey was conducted to collect information on socio-economic activities related to land use systems change. Statistical analysis was done using SPSS and EXCEL programmes. The results indicate that land use systems in the study area vary spatially across geomorphic units in terms of patterns and degree of change. Between 1965 and 2004 areas under fallow bushland, fallow bushed grassland, reserved wooded grassland and reserved woodland decreased as a result of increasing area under agricultural land use systems. Geomorphic and soil characteristics are the major biophysical factors influencing dominant land use system pattern and change in the study area. Demographic change, land tenure and farming practices were the socio-economic drivers of the observed land use systems change. Land use systems change has influenced the people’s livelihood in the study area by increased household income. Increase of cultivated land with tree crops correlated significantly with price of cashewnut (R = 0.8582, P<0.05) and gross income (R = 0.8396, P<0.05) whereas cultivated land with annual crops correlated negatively with market accessibility (R = 0.8906, P<0.05). In view of observed land use systems dynamics, further research is recommended to come up with comprehensive policy guidelines to check the imbalance between the cashewnut and annual crop production to safeguard food security while at the same time conserving the environment.
Land use/cover changes and their influence on the occurrence of landslides: a case study of the northern slopes of the Uluguru mountains, Morogoro, Tanzania
(Sokoine University of Agriculture, 2007) Hieronimo, Proches
The present study was conducted to assess land use/cover changes and their influence on the occurrence of landslides in the northern slopes of Uluguru Mountains, Tanzania. The study focused on the determination of the historical land use/cover changes between 1964 and 2004, evaluation of the biophysical and socio-economic factors influencing land use/cover changes, and examination of the influence of land use/cover changes on the occurrence of landslides. Field survey, remote sensing and GIS techniques were employed to assess land use/cover dynamics. Landslides were mapped through field surveys using GPS and imported in GIS environment. A questionnaire survey was conducted to collect information on socio-economic activities responsible for land use/cover changes and on landslides. Statistical analysis was done using SAS and SPSS softwares. The study demonstrated that land use/cover is dynamic and varies spatially both in terms of coverage and change. Natural vegetation is increasingly replaced by cultivation and urbanisation. Change to rainfed agriculture is more intensive on the mountain ridges by two-fold that of mountain foothills. Urban expansion is very rapid on undulating plains at a mean rate of about 15 ha per year compared to 2 ha per year on the mountain foothills and <1 ha per year in the mountain ridges. Geomorphic characteristics, soils, rainfall distribution and demographic changes are key factors influencing land use/cover dynamics. Land use/cover dynamics (increase in rainfed and irrigated agriculture) greatly influence the occurrence of landslides (R = 0.999, P< 0.05). The observed land use/cover dynamics and their relationship with the occurrence and frequency of landslides call for further research on the effectiveness of different land use options on landslide rehabilitation. Farmers should be sensitised on the influence of land use changes on land degradation and the importance of appropriate soil and water conservation measures to mitigate landslides disasters in the study area.
Magnitude of soil erosion on the northern slope of the Uluguru Mountains, Tanzania: Interrill and rill erosion
(Elsevier, 2008) Kimaro, D. N.; Poesen, J.; Msanya, B. M.; Deckers, J. A.
The magnitude of interrill and rill erosion was determined on the northern slopes of the Uluguru Mountains, Tanzania which is representative for larger areas of East African Arch Mountains, where population pressure is high and land degradation is severe. The aim of the study was to develop a database to support soil conservation in the area. The study was done on two distinct geomorphic units with respect to altitude and hence rainfall distribution pattern: mountain ridges with an altitude ranging from 1000 to 1500 masl and mean annual rainfall of 2300 mm and mountain foothills whose altitude and mean annual rainfall are 550 to 900 masl and 900 mm, respectively. Total soil loss was measured on 36 individual bounded plots measuring 1.2 m × 20 m using Gerlarch troughs on each day with rain from July 2000 to June 2001. The plots were located on six different geopedologic units, nine on mountain ridges and the rest on the mountain foothills. The slope gradient on the terrain ranged from 30% to 70%. The plots were put under maize cultivation as the main crop. Soil loss through rill erosion was estimated by volumetric measurements of rills on each soil erosion plot. The soil loss due to interrill erosion was obtained by subtracting soil loss through rill erosion from the total soil loss measured in the Gerlarch troughs. The results indicate that soil loss due to both interrill and rill erosion was very high with mean soil loss of 69 and 163 t/ha/year, respectively. Rill erosion accounted for about 58% of the total soil loss while interrill erosion contributed to the remaining 42%. Both interrill and rill erosion were higher in the mountain ridges with mean soil loss of 88 t/ha/year and 210 t/ha/year compared to 49 and 116 t/ha/year in the mountain foothills, respectively. Rill erosion was significantly higher (P ≤ 0.001) in all geopedologic units with slope gradient above 40% (mean soil loss ranged between 91 and 258 t/ha/year) compared to interrill erosion with mean soil loss varying from 41 to 115 t/ha/year. In geopedologic units with slope gradient above 60% both interrill and rill erosion were highly active while in geopedologic units with slope gradient below 40% the two processes were less active. The results demonstrate that rill erosion is more important than interrill erosion in the study area particularly where the slope gradient exceeds 40%. The results further show that the major part of the studied area has moderate interrill erosion (10–50 t/ha/year) and severe to very severe (N 100 t/ha/year) rill erosion. This study clarifies the magnitude of interrill and rill erosion which is important for designing soil conservation on agricultural fields.
Effect of grating, chipping, dry fermentation and sun drying on cyanide level of cassava in Tongwe village.
(Sokoine University of Agriculture, 2009) Khatib ,M. A.
This study was conducted to evaluate effectiveness in cyanide reduction by four different methods of processing cassava roots, two traditional (dry fermentation and direct sun drying) and two improved methods (grating and chipping) and also assess losses due to cassava processing in Tongwe village (Muheza District). Presence of mycotoxin-producing organisms in fermented cassava flour was examined. Cyanogens were determined using the AOAC alkaline titration method. The microbial growth was done on plate using Sabouraud’s Dextrose Agar (SDA). The cyanide level, in the processed cassava differed significantly (p<0.05). Improved methods were more effective than traditional. The mean cyanide was; 6.79, 7.96, 8.96 and 9.90 mg HCN/kg DWB for grating, chipping, dry fermentation and direct sun drying, respectively. Identification of mould revealed the absence of mycotoxin producing organisms and therefore ruled out the possibility of presence of mycotoxins in the dry fermented cassava flours collected from 60 households in Tongwe and 10 samples prepared in Tongwe cassava processing unit. Losses due to processing in all four methods were determined by calculating the difference between peeled fresh cassava weight and the weight of flour produced after processing. Results showed significant differences (p<0.05) between the traditional and improved methods studied. The mean percentage losses were; 67.28, 69.73, 51.83 and 54.14 for grating, chipping, dry fermentation and direct sun drying, respectively. Sensory evaluation done at SUA and Tongwe showed significant differences (p<0.05) in preferences between the stiff porridge prepared using flour from all four methods of processing cassava, the most preferred product being ugali from chipped cassava flour. This experiment has indicated that improved methods are more effective in cyanide reduction than traditional ones. However, traditional methods were more economical in processing losses and that there were no mycotoxin-producing organisms in fermented cassava flour. Both methods produce acceptable products worth encouraging if losses are minimized.
Simulation of water productivity for Maize under drip irrigation
(Tropentag, 2011) Festo, R.; Bobert, J.; Mahoo, H.; Kashaigili, J.
Water has become increasingly scarce in most of the countries in the world. To use the available water efficiently in crop production, agricultural water productivity (WP) need to be improved. Drip irrigation systems and deficit irrigation practices are the most ef- ficient methods in improving WP. Availability of soil-water-crop simulation and climatic models can also help in the efforts to improve WP. A study was conducted in Morogoro using CROPWAT model to simulate water productivity of maize under drip irrigation by supplying different water deficits. A completely randomised block design was used with three replications and four treatments. The treatments were T1, T2, T3 and T4 represen- ting 60, 40, 20, 0 percent deficit of ETC (crop evapo-transpiration) respectively. Biomass accumulation (at 45 and 75 days after planting; DAP), grain yield and harvest index we- re determined for each treatment and experimental yield reductions were calculated. The CROPWAT simulation was done for each water deficit level and yield reductions were recorded. A comparison was made between experimental and simulated yield reductions. The mean biomass production between the treatments at 45 DAP were not significant dif- ferent (p < 0.05). At 75 DAP mean biomass production (0.684, 0.728, 1.049, 1.378 kg m-2 for T1, T2, T3 and T4 respectively) were highly significant different (p < 0.05). The mean grain yield between treatments, mean water productivity (1.67, 2.2, 1.78, 1.72 kg m-3 for T1, T2, T3 and T4 respectively) and harvest index values were significant different (p < 0.01). Experimental and CROPWAT simulated yield reductions were not significant different (p < 0.01) at all stages for all the treatments. The CROPWAT model adequately simulated the experimental yield response to water for maize (maize water productivity).
Yield response of different local and hybrid paddy varieties to different ponding depths
(Sokoine University of Agriculture, 2011) NYIRENDA,EMMANUEL MABVUTO
The combined increase in demand for food and scarcity of water worldwide highlights the need for prudent use of water resources. Agriculture, particularly, paddy production, faces two major challenges: (i) to save water; (ii) to increase productivity. One way to deal with this situation is using water saving regimes at field scale. This study therefore was aimed at evaluating some of the water-saving cultural practices in paddy production under Tanzanian conditions. Four different ponding levels (5 cm, 3 cm, 0 cm and the control based on ETc replenishment) represented the main plots while the paddy rice varieties were randomly assigned as sub-plots in each of the main plots. The experiment was designed as 4 x 4 factorial arrangement of treatments in a split- plot design replicated three times (three blocks). Yield, water productivity and seepage and percolation were assessed for each sub-treatment. Results showed no significant difference (p< 0.05) in yield of the varieties as a result of ponding depths and no significant interaction between ponding depth and variety. However, the variety effect on yield was significant. On the other hand, there was significant interaction between ponding depth and variety in terms of water productivity. About 10% of the water applied to whole plot treatments with ponding depths 3 cm and 5 cm was consumptively used. The whole plot treatments based on ETc replenishment resulted in the highest water productivity for all the varieties. Variety TXD88 yielded highest at all ponding levels while the 0 cm ponding level had the least seepage and percolation losses amounting to 78% of water applied. This shows that traditional cultural practices requiring inundation over a long period and using large amounts of water can beii dispensed with at minimal loss in yield but at significantly higher levels of water productivity.
Maize cultivar specific parameters for decision support system for agrotechnology transfer system (DSSAT) application in Tanzania
(2013) Mourice, S. K.; Rweyemamu, C. L.; Tumbo, S. D.; Amuri, N.
In order to develop basis for tactical or strategic decision making towards agricultural productivity improvement in Tanzania, a new approach in which crop models could be used is required. Since most crop models have been developed elsewhere, their adaptation, improvement and/or use outside their domain of development requires a great deal of data for estimating model parameters to allow their use. Cultivar specific parameters for maize varieties in Tanzania have not been determined before and consequently, crop modelling approaches to address biophysical resource management challenges have not been effective. An overall objective of this study was to evaluate DSSAT (v4.5) Cropping System Model (CSM) using four adapted maize cultivars namely Stuka, Staha, TMV1 and Pioneer HB3253. The specific objectives were; to determine maize crop growth and development indices under optimum conditions, to estimate maize cultivar parameters, and to evaluate DSSAT CSM for simulating maize growth under varied nitrogen fertilizer management scenarios. The results indicate that maize cultivars did not differ significantly in terms of the number of days to anthesis, maturity, or grain weight except final aboveground biomass. Also there was no difference between variables with respect to growing seasons. The cultivar specific parameters obtained were within the range of published values in the literature. Model evaluation results indicate that using the estimated cultivar coefficients, the model simulated well the effects of varying nitrogen management as indicated by the agreement index (d-statistic) closer to unity. Also, the cultivar coefficients which are difficult to measure physically were sensitive to being varied indicating that the estimated values were reasonably good. Therefore, it can be conclude that model calibration and evaluation was satisfactory within the limits of test conditions, and that the model fitted with cultivar specific parameters that can be used in simulation studies for research, farm management or decision making.
Investigation of sorghum yield response to variable and changing climatic conditions in semi-arid central Tanzania: Evaluating crop simulation model applications
(2013) Msongaleli, B.; Rwehumbiza, F. B. R.; Tumbo, S. D.; Kihupi, N.
Combination of global circulation models (GCMs), local-scale climate variability and crop simulation models were used to investigate rain-fed sorghum yield response under current and future climate in central Tanzania. Decision Support System for Agrotechnology Transfer (DSSAT) v.4.5 and Agricultural Production Systems Simulator (APSIM) v 7.4 were calibrated and evaluated to simulate sorghum (Sorghum Bicolor L. Moench) var. Tegemeo in 2050s compared to baseline. Simulated median yields from both crop models for the baseline (1980-2010) agree with the trend of yield over the years realistically. The models predicted yields of sorghum in the range from 818 to 930 kg ha-1 which are close to the current national average of 1000 kg ha-1. Simulations by both models using downscaled weather data from two GCMs (CCSM4 and CSIRO-MK3) under the Fifth Coupled Model Intercomparison Project (CMIP5) and Representative Concentration Pathway (RCP 4.5) by mid-century show a general increase in median sorghum yields. Median sorghum yields will increase by 1.1% - 7.0% under CCSM4 and by 4.0% - 12.5% under CSIRO-MK3. Simulations for both current and future periods were run based on the present technology, current varieties and current agronomy packages. This examination of impacts of climate change revealed that increase in sorghum yield will occur despite further projected declines or increase in rainfall and rise in temperature. Modifying management practices through adjustment of sowing dates and the choice of cultivars between improved and local are seemingly feasible options under future climate scenarios depending on the GCM and the direction of the management practice. Our simulation results show that current improved sorghum cultivars would be resilient to projected changes in climate by 2050s, hence bolstering the evidence of heat and drought tolerance in sorghum crop, thus justifying its precedence as an adaptation crop under climate change. We conclude that despite the uncertainty in projected climate scenarios, crop simulation models are useful tools for assessing possible impacts of climate change and management practices on sorghum.
Sorghum yield response to changing climatic conditions in semi-arid central Tanzania: evaluating crop simulation model applicability
(2013) Msongaleli, Barnabas; Rwehumbiza, Filbert; Tumbo, Siza D.; Kihupi, Nganga I.
Decision Support System for Agrotechnology Transfer (DSSAT) and Agricultural Production Systems Simulator (APSIM) were calibrated and evaluated to simulate sorghum (Sorghum Bicolor L. Moench) var. Tegemeo under current and future climate in central Tanzania. Simulations for both current and future periods were run assuming present technology, current varieties and current agronomy packages to investigate rain-fed sorghum yield response. Simulations by both crop models using downscaled weather data from eight General Circulation Models (GCMs) under the Coupled Model Intercomparison Project phase 5 (CMIP5) and Representative Concentration Pathway (RCP 4.5) by mid-century show a mixture of increase and decrease in median sorghum yields. Four GCMs project yields to increase by 5% - 23.0% and one GCM show a decrease by 2% - 9%. Model simulations under the remaining three GCMs give contrasting results of increase and decrease. Adjustment of crop duration to mimic the choice of growing local cultivars versus improved cultivars seems a feasible option under future climate scenarios. Our simulation results show that current open-pollinated sorghum cultivars would be resilient to projected changes in climate by 2050s but things seem better with long duration cultivars. We conclude that crop simulation models show their applicability as tools for assessing possible impacts of climate change on sorghum due to agreement in the direction of crop yield predictions in five out of eight selected GCMs under projected climate scenarios. The findings provide useful guidance and motivation to government authorities and development agencies dealing with food security issues to prioritize adaptations policies geared to ensuring increased and sustained sorghum productivity in Tanzania and elsewhere.
Integrated catchment characteristics, runoffwater reservoir capacities and irrigation - requirement for bean productivity
(2013) Singa, D. D.; Tumbo, S. D.; Mahoo, H. F.; Rwehumbiza, F. B. R.; Lowole, M. W.
Crop production in semi-arid Sub-Saharan Africa (SSA) is limited by over-reliance on rainfall, which is erratic and inadequate. Rainwater conservation and irrigation are needed to avert drought effects and dry spells, and extend crop production activities to dry seasons. A study was conducted from 2011 to 2013 at Ukwe area in Malawi, to determine the size of seasonal open surface reservoir and crop field in relation to catchment characteristics among smallholder farming communities, using beans as a case study crop. There is positive linear relationship between seasonal harvested watershed runoff and rainfall (over 75%). Based on the catchment characteristics and crop water requirement, catchment/cultivated area ratio was 2.1. Harvested runoff water is linearly related to seasonal rainfall amount. About 6000 m3 of water was required to irrigate a hectare of beans. Total volume harvested was estimated to support six-fold the current field area at bean water productivity of 0.7 g L-1. It is possible to determine dry season bean water productivity based on integrated effects of catchment characteristics, runoff water reservoir capacities and irrigation water requirement.
Accuracy of Giovanni and Marksim software packages for generating daily rainfall data in selected bimodal climatic areas in Tanzania
(Tanzania Journal of Agricultural Sciences, 2014) Kahimba, F. C.; Tumbo, S. D.; Mpeta, E.; Yonah, I. B.; Timiza, W.; Mbungu, W.
Agricultural adaptation to climate change requires accurate, unbiased, and reliable climate data. Availability of observed climatic data is limited because of inadequate weather stations. Rainfall simulation models are important tools for generating rainfall data in areas with limited or no observed data. Various weather generators have been developed that can produce time series of climate data. Verification of the applicability of the generated data is essential in order to determine their accuracy and reliability for use in areas different from those that were used during models development. Marksim and Giovanni weather generators were compared against 10 years of observed data (1998-2007) for their performance in simulating rainfall in four stations within the northern bimodal areas of Tanzania. The observed and generated data were analyzed using climatic dialog of the INSTAT program. Results indicated that during the long rain season (masika) Giovanni predicted well the rainfall amounts, rainy days, and maximum dry spells compared to Marksim model. The Marksim model estimated seasonal lengths much better than the Giovanni model during masika. During short rain season (vuli), Giovanni was much better than Marksim. All the two software packages had better predictions during masika compared to vuli. The Giovanni model estimated probabilities of occurrence of rainfall much better (RMSE = 0.23, MAE = 0.18, and d =0.75) than Marksim (RMSE = 0.28, MAE = 0.23, and d = 0.63). The Marksim model over-predicted the probabilities of occurrence of dry spells greater than seven days (MBE = 0.17) compared to the Giovanni model (MBE = 0.01). In general the Giovanni model was more accurate than the Marksim model in most of the observed weather variables. The web based Giovanni model is better suited to the northern bimodal areas of Tanzania. The Marksim model produced more accurate climatic data when the long-term average climate data are used as input variables. This study recommends the use of rainfall data generated using Giovanni software over Marksim, for areas receiving bimodal rainfall regimes similar to the northern bimodal areas of Tanzania.
Enhancing response farming for strategic and tactical management of risks of seasonal rainfall variability
(2014) Admassu, H.; Mahoo, H. F.; Rwehumbiza, F. B. R.; Tumbo, S. D.; Mogaka, H.
Seasonal rainfall variability, particularly the uncertainty with respect to the direction and extent that variability will assume in a given season, forms the greatest source of risk to crop production in semi-arid areas of Ethiopia. Equipping vulnerable communities, in advance, with the expected date of onset of a cropping season, is crucial for smallholder farmers to better prepare to respond and manage the uncertainties. Therefore, rainfall prediction, particularly development of models that can foretell the date of onset of next cropping season is crucial in facilitating strategic agronomic planning and tactical management of in-season risks. A twenty-four-year climatic data study was conducted for Melkassa Agricultural Research Centre (MARC) in semi arid Ethiopia, to develop onset date prediction models that can improve strategic and tactical response farming (RF). A sequential simulation model for a build up of 15 to 25 mm soil water by April 1st, was conducted. Simulation results revealed a build up of soil water up to 25 mm, to be the most risk-wise acceptable time of season onset for planting of a 150-day maize crop. In the context of response farming, this was desirable as it offers the opportunity for farmers to consider flexible combination production of maize (Zea mays L.) varieties of 120 and 90 days in the event of failure of earliest sown 150-day maize crop. Thus, to allow for flexible combination production of the three maize varieties, predictive capacity was found crucial for April onset of the next crop season. Accordingly, based on the consideration of pre-onset rainfall parameters, the first effective rainfall date varied considerably with the date of onset of rainfall. Regression analyses revealed the first effective rainfall date to be the best predictor of the date of onset (R2 = 62.5%), and a good indicator of the duration of next season (R2 = 42.4%). The identified strategic predictor, the first effective rainfall date, enabled prediction of time of season onset and season length by a lead time of two to three months. This markedly improved Stewart’s RF. The date of onset of the next crop season was also found to be a useful predictor of season duration (R2 = 87.3%). Strategic agronomic planning should be adjusted according to the first effective rain date, and tactically according to what date of rainfall onset informs us about expectations in the duration and total season water supply.
Land use determinants of small mammal abundance and distribution in a plague endemic area of Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Kimaro, D. N.; Kihupi, Nganga I.; Gulinck, Hubert; Mulungu, Loth S.; Msanya, B. M.; Leirs, Herwing; Deckers, J.
Small mammals are considered to be involved in the transmission cycle of bubonic plague, still occurring in different parts of the world, including the Lushoto District in Tanzania. The objective of this study was to determine the relationship between land use types and practices and small mammal abundance and distribution. A field survey was used to collect data in three landscapes differing in plague incidences. Data collection was done both in the wet season (April-June 2012) and dry season (August- October 2012). Analysis of variance and Boosted Regression Trees (BRT) modelling technique were used to establish the relationship between land use and small mammal abundance and distribution. Significant variations (p ≤ 0.05) of small mammal abundance among land use types were identified. Plantation forest with farming, natural forest and fallow had higher populations of small mammals than the other aggregated land use types. The influence of individual land use types on small mammal abundance level showed that, in both dry and wet seasons, miraba and fallow tended to favour small mammals’ habitation whereas land tillage practices had the opposite effect. In addition, during the wet season crop types such as potato and maize appeared to positively influence the distribution and abundance of small mammals which was attributed to both shelter and food availability. Based on the findings from this study it is recommended that future efforts to predict and map spatial and temporal human plague infection risk at fine scale should consider the role played by land use and associated human activities on small mammal abundance and distribution.
Contribution of land use to rodent flea load distribution in the plague endemic area of Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Kihupi, Nganga I.; Kimaro, D. N.; Gulinck, Hubert; Mulungu, Loth S.; Msanya, B. M.; Leirs, Herwing; Deckers, J
Fleas associated with different rodent species are considered as the major vectors of bubonic plague, which is still rampant in different parts of the world. The objective of this study was to investigate the contribution of land use to rodent flea load distribution at fine scale in the plague endemic area of north-eastern Tanzania. Data was collected in three case areas namely, Shume, Lukozi and Mwangoi, differing in plague incidence levels. Data collection was carried out during both wet and dry seasons of 2012. Analysis of Variance and Boosted Regression Tree (BRT) statistical methods were used to clarify the relationships between fleas and specific land use characteristics. There was a significant variation (P ≤ 0.05) of flea indices in different land use types. Fallow and natural forest had higher flea indices whereas plantation forest mono-crop and mixed annual crops had the lowest flea indices among the aggregated land use types. The influence of individual land use types on flea indices was variable with fallow having a positive effect and land tillage showing a negative effect. The results also demonstrated a seasonal effect, part of which can be attributed to different land use practices such as application of pesticides, or the presence of grass strips around fields. These findings suggest that land use factors have a major influence on rodent flea abundance which can be taken as a proxy for plague infection risk. The results further point to the need for a comprehensive package that includes land tillage and crop type considerations on one hand and the associated human activities on the other, in planning and implementation of plague control interventions.
Human activity spaces and plague risks in three contrasting landscapes in Lushoto District, Tanzania
(Tanzania Journal of Health Research, 2014-07) Hieronimo, Proches; Gulinck, Hubert; Kimaro, D. N.; Mulungu, Loth S.; Kihupi, Nganga I.; Msanya, B. M.; Leirs, Herwing; Deckers, J.
Since 1980 plague has been a human threat in the Western Usambara Mountains in Tanzania. However, the spatial-temporal pattern of plague occurrence remains poorly understood. The main objective of this study was to gain understanding of human activity patterns in relation to spatial distribution of fleas in Lushoto District. Data were collected in three landscapes differing in plague incidence. Field survey coupled with Geographic Information System (GIS) and physical sample collections were used to collect data in wet (April to June 2012) and dry (August to October 2012) seasons. Data analysis was done using GIS, one-way ANOVA and nonparametric statistical tools. The degree of spatial co- occurrence of potential disease vectors (fleas) and humans in Lushoto focus differs significantly (p ≤ 0.05) among the selected landscapes, and in both seasons. This trend gives a coarse indication of the possible association of the plague outbreaks and the human frequencies of contacting environments with fleas. The study suggests that plague surveillance and control programmes at landscape scale should consider the existence of plague vector contagion risk gradient from high to low incidence landscapes due to human presence and intensity of activities.

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