Theses and Dissertations Collection

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Tableland soil of North-Eastern Brazil:characterization, genesis and classification
(State University of Ghent, 1986) Barrera, Daniel
The coastal low level tablelands of the State of Alagoas are located in the north-eastern region of Brazil between 8° 25' and 10° 20' south latitude, and from 35° 10’ to 37° 15' west longitude of Greenwich. These surfaces formed by Tertiary Sediments are flat or slightly undulated with slopes rarely higher than 4%. It enjoys a tropical climate with a dry summer and a constant temperature throughout the year. The dominant vegetation is formed by the so-called "Atlantic Forest", presenting also minor areas of "Cerrado". Nine profiles corresponding to the soil types present in, a) the well drained surfaces of the tablelands - which classify as Oxisols, Ultisols and Oxisol-Ultisol intergrades -, and b) in poorly drained depressions - classified as Spodo-sols -, were selected for this work. The influence of the morphogenesis of the landscape and the topographical location on soil development is evident from the soils studied. The properties of the soils are strongly related to geomorphic processes. The soils were characterized in terms of their morphological, physico-chamical, mineralogical and micromorphological properties. The sedimentological analysis of the sand fraction(63 - 2000ym) was also carried out. The mineralogy of the sand fraction is similar in all profiles. The light minerals are dominant ( 91-98% ) and almost entirely composed of quartz grains and no more than traces of feldspars. In the heavy fraction the opaques are dominant, ( 84-92% ); among the transparent minerals zircon dominates, followed by tourmaline and rutile. The composition of the clay fraction is also very similar throughout the region, dominated by kaolinite and minoramounts of gibbsite and oxi-hydroxides of iron and aluminium. With the sole exception of profile 2, all the soils are developed from highly uniform parent materials. At the sametime the parent materials of the different soils are also mutually very similar from sedimentological point of view. " Selective erosion 11 of fine soil components as a consequence of run-off is throughout the plateaux the dominant morphogenetic process, which influences the physico-chemical properties, the classification and the distribution of the soils in the landscape. The micromorphological analysis indicates similar features among the dominant soils of the area; and that the illuviation of clay is present in all profiles, which however is not manifested as clay skins in the field as a result of poor structure development. The soils were classified according to Soil Taxonomy, FAO/UNESCO, the Brazilian System of Soil Classification and under the I.N.E.A.C. ( Zaire ) System.
The role of microaggregation in physical edaphology
(Sokoine University of Agriculture, 1993) Mtakwa, Peter W
Soil type and the previous tensile strength and penetration resistance as a (PR) should allow the soil compared ranging fail to failure planes in between the microaggregates. function of easily along Five Tanzanian soil hardsetting Paleustalf from a extreme of strength behaviour, through a Paleudoll, Paleustult, both It was expected (the strength characteristics). that microaggregation types were can I characterized soil strength by measuring affect soil strength. matric potential cultivation history of one at Paleudalf and a to a strongly microaggregated Orthox expected to be at At each site soils that had a history of the weak end of the scale. 7 or more years of cultivation and cropping were compared with newly cultivated soils. The and Orthox Paleustult had the best PR characteristic for ease of root growth and the Paleustalf had the worst characteristic which suggested that it would not permit root growth at matric suctions exceeding 100 kPa. The Orthox also had much the most favourable tensile strength characteristic. At air dryness (100 MPa suction), the previously uncultivated and previously cultivated Orthox topsoils strength. compressive) Paleustalf topsoils. Paleustult) a previous had 3 and respectively, 9 times than less the tensile (and corresponding For three of the soils (Orthox, Paleudoll and history of cultivation was found to have significantly and substantially reduced the tensile strength of the topsoil at any given matric suction compared to the newly cultivated soil
Erosion hazard assessment in the upper ewaso Ng’lro basin of Kenya: application of GIS, USLE and EUROSEM
(Sokoine University of Agriculture, 1999-01-15) Mati, Bancy Mbura
A methodology was developed for assessing soil erosion hazard in the Upper Ewaso Ng’iro basin of Kenya, using Geographic Information Systems (GIS), the Universal Soil Loss Equation (USLE) and the European Soil Erosion Model (EUROSEM). The USLE was used in a GTS environment by creating thematic maps of R, K, L, S, C and P and then calculating soil loss by raster-grid modelling with Arc/Info GRID. The rainfall erosivity factor (R) was derived from relationships between rainfall amount and erosivity using erosion plot data from within the catchment. The nature of the relationship was found to be a function of agro-climatic zones of the region. Mean annual erosivities ranged from 145 to 990 J m"2 hr"1 For a given amount of rainfall, erosivity was higher in zone IV than in the wetter zones 11-111. The soil erodibility factor (K) was estimated using the USLE nomograph and data from laboratory analysis of field samples collected from representative major soil mapping units. The K-values were low to medium, ranging from 0.10 to 0.25 over 84 percent of the basin. The topographic factor (LS) was obtained by creating Digital Elevation Models (DEMs) of the basin with TOPOGRIDTOOL of Arc/Info. These were then used to determine the slope steepness and length factor values, calculated with raster-grid modelling. Although DEMs proved a useful tool, maximum values of both steepness and length had to be set in this reconnaissance study to achieve reasonable results. A finer resolution of input data and a smaller grid cell size are needed for accurate determination. The cover and management factors (C) were obtained by determining the land cover types within the basin using remotely sensed data (SPOT 1 colour composite prints) and ground truthing studies. The factor values were estimated from USLE guide tables and measurements of cover from plots and test sites. Some 70 percent of the basin is covered by rangelands. The conservation practice (P) factor values were estimated from USLE guide tables and then applied to areas where soil conservation had been introduced according to maps obtained from the Ministry of Agriculture. The USLE was validated using data from erosion plots. A value of R2 = 0.645 was obtained between predicted and measured values but the standard error was rather high (e = 5.745 t ha"1 yr"1). Using an annual soil loss of 9.0 t ha"1 yr"1 as tolerance level, some 36 percent of the basin was found to experience unacceptably high erosion rates. Most of this area was communal grazing land and cropland where soil conservation measures had not been applied. A critical land cover type within the grazing land is shrubland, where vegetation cover is less than 40 percent and high erosion risk was predicted and confirmed by field surveys. EUROSEM could not be integrated within a GIS in the time available for research. It was therefore simulated outside GIS environment, where it was applied to Embori and Mukogodo plot data using separate data sets for calibration and validation. Calibration was used to obtain input parameters for saturated hydraulic conductivity, cohesion and Manning’s roughness coefficients. Validation gave correlation coefficients of 0.907 and 0.840 for predictions of storm runoff and soil loss respectively at Embori; the corresponding values for bare soil plots at Mukogodo were 0.895 and 0.577. However, EUROSEM predicted runoff poorly (R2 = 0.570) and failed to predict soil loss at all the vegetated plots at Mukogodo. The model was applied to simulated vegetation covers of barley, maize, grass and forest for a 36.7 mm rainstorm at Embori. The simulated soil losses showed an exponential decrease with increasing cover. At a threshold cover of 70 percent, soil loss diminished to zero under grass and forest and decreased to a minimum value under barley and maize. These results support the USLE simulations, which showed that areas with more than 70 percent cover (such as forest) had a low erosion hazard, even with steep slopes and high rainfall erosivities. This research has demonstrated that GIS can be used with the USLE to assess and quantify erosion hazard, giving results that can be used for conservation planning. EUROSEM can be applied successfully to bare soil and cropland, but application to other land covers requires further investigation. Land cover and topography are the main factors controlling the spatial distribution of soil loss in the Upper Ewaso Ng’iro basin. Future conservation activities should be concentrated on the rangelands.
Agronomic evaluation of some industrial wastes as alternative sources of plant nutrients in Morogoro District, Tanzania
(Sokoine University of Agriculture, 2001) Ndaki, Stephen Mhoja Mashauri
A study’ was conducted at Magadu. Morogoro. Tanzania to evaluate the industrial wastes as alternative sources of plant nutrients and/or soil conditioners. The soil of Magadu was classified by Kaaya (1989) as Oxic Haplustult. The soil was characterised in this study for its physical and chemical properties prior to planting of the test crop. The analytical data showed that the soil was strongly acidic with a pH of 5.1. Total N. available P. %OC, exchangeable Ca and Na. CEC. and DTPA extractable Zn were in the low range. Exchangeable Mg was in the medium range, while exchangeable K. DTPA extractable Fe, Mn and Cu were high. In the field a randomised complete block design was used to evaluate the wastes using maize as test crop. The rate of waste application were 5.24 4.8, 4.25, 4.5 and 3.7 tonnes/ha of waste tea, wattle bark chippings, waste tobacco, wood ash and saw dust respectively. Prior to soil incorporation, the wastes were analysed for their chemical properties. Maize dry matter yields were significantly higher in plots which received 5.24 tonnes/ha of waste tea followed by plots which received 4.25 and 4.5 tonnes/ha of waste tobacco and wood ash respectively. Maize grain yields were significantly higher in waste tea and wattle bark chippings amended plots than in the other waste amended plots. At the end of the growing season the soil was analysed to evaluate the residual effect of wastes on soil properties. Soil pH, available water capacity, available P, % OC, total N, exchangeable bases, CEC, DTPA extractable Zn and Cu in waste amended plots increased in the top 15 cm of soil relative to the control plots. DTPA extractable Fe and Mn, exchangeable Al and acidity were significantly reduced in all waste treatments. Total N and % OC in wood ash and saw dust amended plots were at par with those found in control plots. The results from the field suggested that when applied at agronomic rates, industrial wastes can produce satisfactory plant growth and yields. The results revealed further that waste application on a long term basis will allow good build up of soil organic matter and plant nutrients which in turn will improve on soil productivity. It is recommended that N supplement to wood ash which is rich in almost all macro and micronutrients (except N) would balance its nutrient supply to plants. A glasshouse decomposition experiment was carried out with some wastes including sawdust and wattle bark chippings in perforated plastic litter bags. The wastes were either surface applied or buried to 10 cm depth in wooden troughs. The decomposition process which was monitored at 0. 3, 6, 9, and 12 weeks of incubation revealed that soil incorporated wastes decomposed and released nutrients faster than surface applied ones.
Effects of Land Degradation in the uplands on Land use Changes in the Plains: The case study of Chimala River Catchment in the Usangu plains
(Sokoine University of Agriculture, 2002) Mwalukasa, Emmanuel Hudson
A study was carried out in Chimala River catchment in Makete-Iringa (uplands) and Mbarali-Mbeya (plains), Tanzania to relate land use changes occurring in the plains to upland degradation. The objectives of this study were: (a) to establish land use/cover inventory for the catchment; (b) to assess upland vegetation degradation; (c) to assess upland soil erosion by gully expansion; (d) to assess catchment soil fertility status; (e) to assess the Chimala River water flow trend; and (f) to assess the socio-economic activities related to land degradation. Aerial photographs and satellite images were used, interpreted and analysed using GIS ArcView/ArcINFO and ERDAS Imagine softwares. Mean monthly water levels were compared using a student t-Test. Soil samples were collected from four different forest-covers for organic carbon (OC) content analyses. Total nitrogen (N) contents were estimated using C:N ratios. A structured questionnaire and SPSS programme were used to collect and analyse socio-economic survey data. Results showed that upland grassland decreased by 3.6% and 45.8% for 1963-77 and 1977-2001 periods respectively due to extending cultivation activities. On the scarp, dense and open woodlands decreased by 56.2% and 4.6% respectively for 1963-77 while for 1977- 2001 dense woodland decreased by 100% due to firewood collection; open woodland increased by 21.2% through regeneration. Gully erosion expanded by 206% between 1963 and 1977 because of poor land management but decreased by 69% for 1977-2001 through natural recovery and afforestation. Consequently upland vegetation degradation and gully erosion caused soil transfer from the mountains and deposition in the plains. About 0.4% (1977) and 0.6% (2001) of the catchment area under irrigation were abandoned to bushland due to siltation problems. River valleyiii soils in the plains indicated adequate OC (3.4%) due to alluvial deposition thus attracting more agricultural activities. Low OC (0.61-1.09%) indicated low N (0.06- 0.11%) as a limiting factor for paddy rice production in upper areas of the plains. No significant variations (P<0.05) in the stream flows of Chimala River were observed between 1960 and 1993 as a result of upland degradation. It is therefore concluded that upland degradation has contributed significantly to land use changes/degradation occurring in the plains that calls for more efforts to safeguard land resources in the uplands by concerned stakeholders
Assessment of the fertility status of soils of rice growing areas of Same District, Kilimanjaro Region, Tanzania.
(Sokoine University of Agriculture, 2003) Amur, Nyambilila
This study was conducted to assess the fertility status of the soils of rice growing areas of Same district. Thirty soil samples were collected from ten different sites where rice is grown. Following laboratory analysis, three bulk soil samples were collected from Kisiwani, Ndungu and Kihurio for pot experiments. The laboratory analysis included determination of total N, organic carbon, P by Bray 1 and Olsen methods, and exchangeable bases by ammonium acetate saturation. The micronutrients were determined by extracting with 0.005M DTPA at pH 7.3. The response of rice (Oryza saliva L) variety super SSD5 to N, P and K, as well as to different levels of Zn were assessed in a glasshouse experiment where plants were grown for 56 days. The harvested plant samples were analysed for N, P, K, Ca, Mg, Zn and Fe using the HNO3-H2O2 wet digestion procedure. The results showed that all the soils in this study were deficient in N. About 53% of the soils had low available P. All the soils had adequate levels of K, Ca, Mg and Na, with the exception of soils from Ndungu, which had a low K, supply. Also, most of the soils had low Zn levels, and only two sites had adequate Zn levels. Soils from Mbugani had low Fe while the rest had adequate Fe and Cu. The glasshouse experiments showed that application of N, P and K increased rice dry matter yields in all the soils used. It was further revealed that Zn supplementation in addition to NPK also increased rice dry matter yields further. The results also indicated that the uptake of each nutrient applied was consistent with the dry matter yields increases. It was concluded that most of the soils under rice cropping in the district were deficient in N, P and Zn and required fertilisation using these nutrients. Iron was also required in Mbugani soils, whichiii were deficient of this element. Field experiments are recommended to confirm these initial findings.
Effects of limestone, Minjingu phosphate rock and green manure application on improvement of acid soils in Tonga Butare, Rwanda
(Sokoine University of Agriculture, 2003) Nabahungu, Leon Nsharwasi
A study was conducted under pot and field conditions to assess the effects of limestone, Minjingu Phosphate Rock (MPR) and green manures (GMs) on maize yield, soil properties and nutrient uptake. The treatments tested in the greenhouse experiment were four rates of limestone applied either alone or in combination with MPR and/or green manures. In the field experiment, 13 treatments were tested namely an absolute control, recommended rate of NPK and burned lime, NP and limestone, combinations of any two of the following materials: limestone, MPR, Tithonia GM, Tephrosia GM, and combinations of three of these amendments. Soil analysis at the beginning of the experiment revealed that the soil was deficient in N, P, and K, had low levels of Ca and Mg and toxic levels of exchangeable AI. Application of GMs improved the supply of N and K appreciably while limestone played a great role in reducing exchangeable AI. A significant contribution of P was from MPR. A combination of MPR, GMs and limestone supplied ample amounts of N, P, K, Ca, Mg and reduced exchangeable AI and hence resulted into high yield. However, high rates of limestone decreased DM yield and nutrient uptake in the treatment with three amendments. A significant increase in DM yield was obtained in pots, which received a combination of low rate of limestone (1/4 of the lime requirement), MPR and GMs. In general Tithonia application gave higher yields than Tephrosia. These results were consistent with the higher quality of Tithonia biomass relative to Tephrosia biomass. The green manures in combination with MPR increased P uptake significantly. Nutrient concentration data from both field and pot experiments indicated serious deficiencies of P, K and N consistent with soil analysis data but Ca, Mg, Zn and Cu were in the sufficiency range. Furthermore, the results indicated that using a combination of moderate rates of limestone, MPR and GMs is the best strategy in improving acid soils in Tonga, Rwanda.
Evaluation of the potential of green manure and plant extracts for the control of witchweed (strig a asiatica l. kuntze) in upland rice (oryza saliva l.) in Kyela, Tanzania
(Sokoine University of Agriculture., 2004) Mohamed, Juma Kayeke
Striga asiatica is a serious problem in upland rice in Kyela Tanzania. The use of inorganic nitrogen fertilizer urea assures control of the weed. Resource poor farmers cannot adopt the technology due to unavailability and higher prices of inorganic fertilizers. Therefore, the use of green manure available in upland rice fields will be a plausable alternative. Three experiments were conducted to evaluate the potential of green manure and plant extracts for the control of Striga asiatica (L.) Kuntze on upland rice (Oryza sativa L). These experiments aimed at evaluating the decomposition of the green manure, determining the effect of the green manure and inorganic fertilizer on Striga and rice yield and determining the influence of green manure and plant extracts on the germination of Striga. Decomposition of roots and shoots of Crotolaria ochlroleuca G. (sunhemp), Mimosa invisa L.(CoIla), and Cassia obtusifolia L.(Sicklepod) was determined. Results showed that by the 2nd week shoots had lost 51% of the biomass while by the 6lh week roots had lost 50% of the biomass. Then inorganic fertilizer urea at 0 N, 25 kg N ha'1 and 50 kg N ha'1 was superimposed in green manure plots. Generally, it was found that Striga infestation was reduced by 100% while the yield of rice increased from 1238 kg ha’ to 2846 kg ha'1. However, the residual effect of green manures did not reduce Striga but increased rice yield. High benefit per unit cost was realised on when C. ochlroleuca was combined with 50 kg N ha'1). Green manure application methods (ploughing under, mulch) was also superimposed with inorganic fertiliser urea (0 N, 25 kg N ha' 1 and 50 kg N ha '). Results showed that there was no significant difference between mulch and ploughing under on Striga except for rice grain yield. Mulch was found toiii be more economical than ploughing under. The potential of green manure to stimulate Striga germination, plant extracts to suppress Striga germination and application methods was also determined in the laboratory and field. Striga germination was found to be in the order C. ochlroleuca C. obtusifolia > M. in visa (both field and laboratory). Plant extracts were collected from C. ochlroleuca, M. invisa, C. obtusifolia, Vernonia amygdalina Del. (bitter leal), Neuritania niitis, Dolichos kilimandcharis and Gnidia kraussiana Mcisn. (yellow heads). It was found that Striga seed germination was reduced where D. kilimandcharis and G. kraussiana were found to be effective in suppressing Striga seeds germination. Seed hardening was selected as a good application method. Crotalaria ochroleuca and C. obtusifolia were recommended for Striga control and improvement of soil fertility in Kyela.
Effects of green manure and compost amended with phosphate rock on soil properties, yield and quality of amaranth and tomato.
(Sokoine University of Agriculture., 2004) Minja, Ruth R.
A study was conducted in Iringa, Tanzania to evaluate the potential of crotalaria (Crotalaria ochroleuca) green manure and compost applied alone or amended with Minjingu phosphate rock (MPR) as sources of N and P and their effects on selected soil physical and chemical properties, plant nutrient concentration and uptake, yield and some quality attributes. Two field experiments, one for amaranth and the other for tomato were conducted using a split plot design with three replications. Crop cultivars were main plots while fertilizer treatments constituted the sub plots. Two amaranth species (Amaranthus cruenlus and Amaranthus hypochondriacus) and two tomato cultivars, Tanya (determinate) and Tengeru-97 (indeterminate) were used. Fertilizer treatments included crotalaria as green manure, crotalaria + MPR, compost, compost + MPR and NPK which was used as the standard. The results indicated that compost was more effective than crotalaria in increasing organic matter and soil moisture content. Crotalaria contributed more N to the test crops than compost. Amendment of compost or crotalaria with MPR enhanced P supply, plant N and P uptake and relative agronomic effectiveness (RAE). All fertilizer materials were able to supply adequate levels of N and P as required by the two crops at their critical growth stages. The tested materials significantly increased yields, vitamins C and A, and crude protein of the two crops. The yields and nutrient content levels obtained for the two vegetables were within the range reported in literature. There were significant and positive correlations between soft available N, P and yield, protein, calcium, iron, vitamin C and A contents of the vegetables. Keeping quality of the vegetable crops was mostly influenced by their Ca contents probably due to the role of Ca in cell wall synthesis and integrity. Due to its high Ca content, MPR-amended treatments increased the evaluated keeping quality attributes of the test vegetables. It is therefore recommended that the tested organic materials could be attractive sources of N and P in organic production of tomato and amaranth. Application of crotalaria and compost should be supplemented with P sources such as MPR in order to increase their P contents. Soil fertility improvement programmes in this area and others with similar soil properties should include farmers training on proper management of organic materials such as application methods, storage and time of application.
Use of minjingu phosphate rock combined with different organic inputs in improving phosphorus availability and maize yields on a chromic acrisol in Morogoro, Tanzania
(Sokoine University of Agriculture, 2004) Ikerra, Susan Tinkishaba
Phosphorous deficiency in highly weathered soils is one of the causes of low crop yields in Tanzania. Use of Minjingu phosphate rock (MPR) in combination with organic inputs is considered to be a possible option for increasing P availability and crop yields. However, detailed characterization of organic inputs, the effects of organic inputs when used alone or combined with MPR on soil characteristics and, consequently, maize yields, are limited. The objectives of this study were to characterize farmyard manure (FMY), tithonia, lantana and gliricidia and to evaluate the influence of MPR combined with these organic inputs on soil properties, P availability and maize yields from a Chromic Acrisol. The study consisted of incubation, pot and field experiments. Characterization of organic materials showed that manure and tithonia had more P than the critical value for net P mineralization. Tithonia contained the highest amounts of light molecular weight organic acids (LMWOA), oxalic acid being the most dominant. An incubation experiment showed that all organic materials depressed MPR dissolution, and the depressing effect increased with increase in pH, Ca and P content of the materials. Incubation and pot experiments showed that organic materials at 2.27 g kg'1 (5 t ha'1) increased soil pH, exchangeable Ca and decreased exchangeable Al. All organic materials increased labile P pools and reduced P adsorption maximum and P affinity in the incubation and field experiments. This resulted in increase in available P and consequently, in maize dry matter yields (DMY). Under field conditions tithonia increased soil pH, exchangeable Ca and oxalic acid concentration, and decreased exchangeable Al. Tithonia decreased P sorption and increased total labile P, consequently increasing maize yields. Thedecrease in P adsorption increased with tithonia rates, with the rate of 7.5 t ha'1 resulting in the largest agronomic optimum. MPR was superior to TSP (80 kg P ha'1) in increasing pH, Ca, oxalic acid and in reducing exchangeable Al. Both sole MPR and sole TSP reduced P adsorption but the influence of MPR was greater than that of TSP. Tithonia at 7.5 t ha'1 had similar P adsorption maximum to sole MPR at 80 kg P ha'1. Combining MPR at 40 kg P ha’1 with tithonia at 7.5 t ha'1 had adsorption maximum similar to that of sole tithonia at 7.5 t ha'1 or MPR at 80 kg P ha'1. Both MPR and TSP increased Ca and P uptake and maize yields in pot and field experiments. MPR was superior to TSP in supplying Ca, oxalic acid and in increasing pH in all seasons. Combining MPR with tithonia had a higher RAE in two out of the three seasons than that under sole tithonia or MPR. Organic materials alone or combined with MPR improved soil pH, Ca and decreased exchangeable Al, consequently increasing P availability and maize yields. Combining MPR with organic materials resulted in increase in P availability by reducing P adsorption rather than by enhancing MPR dissolution. Co-application of MPR with tithonia on Chromic Acrisol is recommended. Evaluation of the influence of tithonia on some chemical, physical and biological soil properties under various climatic conditions and for longer periods of time is essential so as to be able to better exploit this resource.
Strategies for establishing adequate phosphorus levels in three soils with different phosphorus fixing capacities
(Sokoine University of Agriculture, 2004) Eliuth, Stephan Ngailo
A study was conducted under pot and field conditions to establish adequate levels of phosphorus in three soils with different P fixing capacities. These soils were from Magadu, Morogoro District, classified as Oxic Haplustidt, Sasanda, in Mbozi District, classified as Drystropept and Nkundi in Nkasi District, classified as Acruoxic Kancliustult. A pot experiment was conducted at SUA- Department of Soil Science while field experiment was carried out at Sasanda in Mbozi District in Mbeya region. The treatments were 0, 40, 80 and 160 mg P/kg of soil for Nkundi, 0, 100, 200 and 400 mg P/kg of soil for Magadu and 0, 800, 1600 and 3200 mg P/kg of soil for Sasanda soil. For field experiment the treatments were 0, 800, 1600 and 3200 kg P/ha. The sources of P were TSP and MPR. There were seven treatments for field and eight treatments for pot experiment. The experiment was laid out in a Randomized Complete Block Design. The tested crop was maize {Zea mays var UH 615). The objectives of the study were to identify rates of P required for optimizing maize dry matter grain yields, and associated available P levels in the soils. Results of the study showed that, both TSP and MPR were effective sources of P in the soils studied. Both TSP and MPR significantly (P = 0.05) increased DM and grain yield, P uptake and available P over the control by 97.7, 95.8, 76,8 and 95.3%, respectively in Sasanda soil. This was attributed to 95.3% increase in available P in the soil after TSP and MPR application in Sasanda soil. This was supported by the highest grain yield, DM yield, and P uptake of 2.97 t/ha, 64.18 g, and 124.8 mg/kg at the rates of 3200 kg P/ha and 3200 mg/kg, respectively in Sasanda soil. However, MPR was slightly less effective than TSP for most of the aspects studied. The optimum rates were 160, 200 and 3200 mg P/kg for Nkundi, Magadu and Sasanda soils, respectively under pots. However, these rates have to be confirmed under field conditions. In Sasanda field experiment, P application did not significantly (P = 0.05) increase available P and the available P was below the critical level. This was attributed to high fixing capacity of the soil. The rale of 1600 kg P/ha gave the highest grain yield of 2.97 t/ha in the current study. Results from the current study indicated that MPR has the potential of supplying P for maize production therefore it could be used as an alternative source of P to TSP. A large, one-time application of P on highly P deficient soils is not always the solution for correcting P deficiency in all soils like in Sasanda soil. A gradual seasonal P application might be the most cost-effective approach for high P-fixing soils.
Influence of cover crops on nitrogen availability, soil moisture content and maize yield under sub humid climate of Morogoro, Tanzania
(Sokoine University of Agriculture, 2005) Kalumuna, Matilda Charles
A study was conducted in Morogoro Tanzania, for 3 consecutive years to evaluate the influence of cover crops planted in short rains on nitrogen (N) availability, soil moisture and grain yield of the subsequent maize crop planted in the long rains. The cover crops namely cowpea (Vigna unguiculata [L] Walp.), lablab (Lablab purpureus, L.), mucuna (Mucuna pniriens) and pumpkin (Cucurbita maxima') were evaluated against weed and bare fallows in Randomized Complete Block Design (RCBD) replicated three times. Cover crops residues had N content 2%. Pumpkin, although not a legume, had high quality residues, having 2.1% N and higher P (0.25% P) and base content than other cover crops. Mucuna was the only cover crop that produced an average biomass above the threshold of 2 Mg DM ha'1. Mucuna biomass was significantly higher (P < 0.05) than that of the other cover crops, ranging from 2.7 to 5.1 Mg DM ha'1, with good short rains and accumulating 63 to 118 kg N ha'1. At the end of the short rainy season, mineral N after mucuna increased by 2 to 30% and was significantly higher (P < 0.05) than after the other cover crops. Seventeen and 35% of N accumulated in pumpkin and cowpea residues was released in the first 7 days of incubation, respectively. These were significantly higher than the 4 and 6% accumulated N in lablab and mucuna residues, respectively. At 35 days of incubation, mineral N released from lablab, pumpkin and mucuna residues was 19, 34 and 31% of the applied amount, respectively. Mucuna and lablab significantly increased soil moisture reserve in the 40 - 60 cm soil layer (P < 0.05) by 9 mm in the short rainy season whereas pumpkin and weed fallow reduced it by 3 and 4 mm, respectively. In the long rainy seasons, mucuna and lablab reduced runoff from 30 - 45% to 6 - 15% of rainfall. Mucuna significantly increased the number of maize plant silking (P < 0.05) at 53 days after planting by 15 - 17% over weed fallow and maize grain yield by 3 - 4 fold in seasons with insufficient long rains. It is recommended that in order to increase maize production in the sub humid area of Morogoro, mucuna should be planted in the short rains instead of leaving the land under weed fallow and supplemental mineral N fertilizer should be topdressed at 28 to 35 days after maize planting.
Screening coalmon bean [Phaseolus vulgaris l. savi] genotypes adapted to low soil phosphorus
(Sokoine University of Agriculture, 2006) Mourice, Sixbert Kajumula
Two screen house pot experiments were conducted to identify bean genotypes, diverse in their places of origin and seed size, based on vegetative growth and P uptake and final grain yield for adaptation to low phosphorus. Three phosphorus levels; low P (0 added P), medium P (40 mg P/kg soil) and high P (160 mg P/kg soil) were main plots whereas 27 genotypes were subplots, in a split-plot laid out in a completely randomised design. The test soil was very fine, kaolinitic Kanhaplic I-Iaplustult. Out of 27, seven bean genotypes were further evaluated for yield components and final grain yield at low P in the same soil. Shoot biomass, root biomass, shoot P concentration and P uptake increased with increased P supply and genotypic variability in these parameters was significant (P < 0.05). Genotypes G92, PRETO 143, MILENIO, VEF 88(40), BAT 477, A785, ANT 22, DOR 714 and AFR 708 performed better than other genotypes at low P level; also their response to P addition was significant. It was revealed that P was a major limiting factor to bean growth in the soil used for the experiment. Number of pods/plant increased significantly with increase in P levels and was correlated with grain yield at low P and adequate P. P treatments did not affect the seed size of genotypes. Genotypes BAT 477, MILENIO, DOR 714 and A785 had significantly higher grain yield than other genotypes at low P and may be favoured in the selection process. Although genotypes produced some grain yield at low P, soil fertility improvement by applying medium P or appreciable amounts of organic manure may improve yields and increase productivity per unit area.
Soil fertility status and response of rice to nitrogen, phosphorus and farmyard manure under rainwater harvesting systems in semi arid areas of Maswa, Tanzania.
(Sokoine University of Agriculture, 2006) Kajiru, Geophrey Jasper
In semi arid areas of Tanzania, rainfed lowland rice production is constrained by inadequate plant nutrients and soil moisture thus restricting plant growth culminating into very low yields. With the adoption of appropriate rainwater harvesting (RWH) technologies the soil moisture stress is significantly alleviated. A study was conducted on the Ndala River Catchment comprised of Isulilo, Njiapanda and Bukangilija villages in Maswa district Tanzania.The objectives were to evaluate the fertility status of the soils and their suitability for rice production and the response of rice (Oryza saliva L. var. Supa India) to farmyard manure (F), phosphorus (P), nitrogen (N) and F-P-N applications over three cropping seasons (2002/03 to 2004/05) at Bukangilija village. The fertility status of the soils and their suitability for rice production were evaluated based on the local and technical indicators of soil fertility and land quality. Nitrogen was applied at the rate of 0, 50 and 100 kg N ha'1 as urea, phosphorus at 0, 30 and 60 kg P ha'1 as TSP and farmyard manure (kraal manure) at 0, 3.5 and 7 t ha'1. The P and F rates were accordingly broadcasted and incorporated into the surface soils one week before rice sowing and N was applied at two equal splits, at tillering and panicle initiation stages. Sowing was done between December and early January based on the long term seasonal rainfall distributions. Based on local and technical indicators of soil fertility, the soils on the catchment were of low fertility status and moderately suitable for rice production under RWH. The major limitations included low total nitrogen and organic matter contents, available zinc, soil moisture retention and high exchangeable Ca: Mg and Ca: Mg: K ratios and high ESP. The F, P and N and F-P-N combinations significantly increasedIll tillering, dry matter and grain yields and N, P and K contents in the rice plants and the main effect increases were in the order N>F>P. The ranges in the number of tillers per hill, dry matter yields, grain yields, N, P and K contents in the rice plants between the control and the highest F-P-N combinations were 10.6, 3522 kg ha’1, 1342 kg ha'1, 25.92 g kg’1, 1.38 g kg‘'and 12.12 g kg'1 , respectively. The rice response to F, N and F and the FPN combinations were due to increased availability and uptake of plant nutrients particularly N, P and Zn. The long term seasonal rainfall amounts and distribution and El-Nino-Southem Oscillation (ENSO) indices gave good and reliable projections on the time of sowing rice seeds in the study area. Based on the generated data farmyard manure, P and N rates at 3.5 t ha’1 30 kg P ha’1 and 50 kg N ha’1, respectively could be adopted for increased and sustainable rice production where R.WH technologies have been adopted on the Ndala River Catchment. Agro-climate extension service should be established.
Screening coalmon bean (Phaseolus Vulgaris L. Savi) genotypes adapted to low soil phosphorus
(Sokoine University of Agriculture, 2006) Mourice, Sixbert Kajumula
Two screen house pot experiments were conducted to identify bean genotypes, diverse in their places of origin and seed size, based on vegetative growth and P uptake and final grain yield for adaptation to low phosphorus. Three phosphorus levels; low P (0 added P), medium P (40 mg P/kg soil) and high P (160 mg P/kg soil) were main plots whereas 27 genotypes were subplots, in a split-plot laid out in a completely randomised design. The test soil was very fine, kaolinitic Kanhaplic H0aplustult. Out of 27, seven bean genotypes were further evaluated for yield components and final grain yield at low P in the same soil. Shoot biomass, root biomass, shoot P concentration and P uptake increased with increased P supply and genotypic variability in these parameters was significant (P < 0.05). Genotypes G92, PRETO 143, MILENIO, VEF 88(40), BAT 477, A785, ANT 22, DOR 714 and AFR 708 performed better than other genotypes at low P level; also their response to P addition was significant. It was revealed that P was a major limiting factor to bean growth in the soil used for the experiment. Number of pods/plant increased significantly with increase in P levels and was correlated with grain yield at low P and adequate P. P treatments did not affect the seed size of genotypes. Genotypes BAT 477, MILENIO, DOR 714 and A785 had significantly higher grain yield than other genotypes at low P and may be favoured in the selection process. Although genotypes produced some grain yield at low P, soil fertility improvement by applying medium P or appreciable amounts of organic manure may improve yields and increase productivity per unit area.
An evaluation of adoption and sustainability of soil conservation practices under small scale farming system of Adama district in Oromia region, Ethiopia
(Sokoine University of Agriculture, 2007) Waritu, Gerishu Bati
Over the years, numerous intervention approaches have been launched to promote improved technologies in order to attain sustainable development. However, extension approaches, which have been the dominant rural development strategy, have been slow in transforming agriculture resulting from low adoption rate of SWC technologies that were aggressively promoted through extension programmes. Thus, this study examines the adoption and sustainability of soil conservation practices looking into the major factors dictating the SWC technology adoption. The study is based on a critical review of literature including analysis of data collected from 120 farmer households and 40 extension field staff. In the study, two analytical techniques, descriptive statistics and logistic regression function, were employed in analyzing data. The results of the study reveal that rural development strategies have been formulated without due consideration to farmers’ indigenous knowledge and participation in development process. Specifically, literature confirms that past extension approaches have been biased against natural resource management and in this regard, except physical soil bund structure, other components of soil conservation packages were found marginalized and the major reason behind the better attention to soil bund is because of the support that the practice has received from SWC related projects over the past years. In this regard, a host of factors, most of which are policy related, were responsible for poor technology adoption and sustainability and the socio-economic factors also were found to be significant in dictating the adoption process. Overall, both the historical review and survey results reveal that integrated natural resource oriented approaches were not adopted and natural resources aspect was neglected. Therefore, from the findings of this study it is strongly recommended that policy makers and technical institutions should readdress the policy related issues and extension system should be revised in such a way that holistic approaches to ensure environmentally sustainable rural development are employed in small-scale farming system.
Characterization of vermiculites from the Mozambique b elt of Tanzania for agricultural applications
(University of Aberdeen, 2009) Marwa, Ernest Melkiory Magesa
Crop productivity in Tanzania is generally low and this is partly due to inadequate and poor retention of plant nutrients and moisture by some soils. The country has several vermiculite deposits, but none of them are exploited to improve the soil properties because of lack of information on their potential suitability. The aim of this research was to establish the suitability of vermiculites from Tanzania as soil improvers for crop production through characterization. The study involved five samples from Tanzania and one from South Africa, which was included for comparison purposes. Mineralogy of the samples was studied by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM) fitted with energy dispersive system (EDS), whereas electron probe microanalysis (EPMA) and inductively coupled plasma-mass spectrometry (ICP-MS) were used to establish elemental compositions. Extractability of some heavy metals in vermiculites was assessed by diethylene triamine pentaacetic acid extraction (DTPA), whilst extractable P was determined by acetic acid extraction. The pH, water release characteristic, and cation exchange capacity (CEC) were among the physical and chemical properties assessed. Pot and field studies were then carried out in Tanzania to assess maize response and retention of macronutrients in a sandy soil amended with vermiculites. Maize was used as a test crop. The results found indicate that not all samples are vermiculites, some are hydrobiotites. Analysis shows that none of them contain hazardous accessory minerals. However, some have elevated concentrations of Cr and Ni, but these heavy metals are insignificantly plant available and do not inhibit the uptake of essential plant nutrients. Hence, the studied vermiculites are safe to exploit for crop production. In addition, all are slightly alkaline with high CEC and, thus, they are suitable as a growing medium with ability to retain plant nutrients from leaching. However, heating above 600 °C should be avoided as it reduces the CEC of vermiculites by more than 90 % and makes some of the exfoliated products strongly alkaline and, thus, unfavourable for crop production. The Tanzanian vermiculites can retain plant-available water but their ability is less than vermiculite from South Africa. The P in these vermiculites is extractable and extractability increases on heating to 400 °C. Further heating makes P insoluble and less extractable. Maize vegetative growth, dry matter yield, and nutrient uptake were significantly enhanced by adding vermiculite to the soil over the control. In addition, it retained and fertilized the soil with P. Pre-heated vermiculite at 600 °C performed better than unheated vermiculite and it inhibited the fixation of the applied K and N. It was concluded that the Tanzanian vermiculites have a recommendable potential of improving soil properties for crop production when heated at a temperature of not more than 600 °C. However, more field trials are recommended on other types of soils and crops other than sand and maize used in order to widen the scope of their utilization in Tanzania.
Soil and water conservation practices in the Uluguru mountains: the influence of high value crops promotion
(Sokoine University of Agriculture, 2009) Malisa, Emmanuel Timothy
In western Uluguru Mountains, professionals have introduced soil and water conservation (SWC) practices which, if properly followed, would conserve the soil and promote agriculture. Various high value crops (HVC) promotion interventions and others which could serve as incentives were executed to aid attainment of this objective. Despite these efforts, today, in most fields we see more of annual ridges, the conventional farming practice which is not effective in SWC and other forms of unsustainable agriculture practices. This study sought to determine the influence of HVC promotion interventions on investment in SWC in Mgeta. It also investigated whether or not appropriate incentives for overcoming adoption barriers have been used. Data were collected through unstructured interviews, observations and interview schedules. Descriptive statistics and multinomial logistic regression were the main methods of analysis. Results were as follows: Age, education and income; farm size and slope have significant influence on investment in SWC. Household size, labour force and occupation were not significant. Land security was the number one incentive followed by agricultural sustainability, farm implements, extension services, irrigation improvement, labour sharing and suitability for growing HVC. The four lowest incentives were rewards and prizes, market development, food-forwork and credit. From regression analysis introduction of HVC had the highest predictive effect on investment in SWC followed by irrigation improvement. Slope and income were also significant. Recommendations are as follows: Promote SWC measures which are cost-effective and can be integrated into existing farming system and promote HVC for cultivating on terraces. In this respect, contour strip cropping,
Effects of copper concentration in soil on prolife ration and survival of rhizobia, nodulation and biological nitrogen fixation in beans, cowpeas and soybeans
(Sokoine University of Agriculture, 2010) Tindwa, H
A study was conducted in which two strains of the fast – growing bean rhizobia- PV 1 and PV 2 and two others of the slow – growing bradyrhizobia for cowpeas and soybean- CP 1 & GM 8 , respectively, were used to test their ability to: - (a) proliferate in copper contaminated liquid media, (b) survive in copper contaminated soil, (c) nodulate respective host legumes and (d) fix nitrogen under increasing copper levels both in vitro and in vivo. Known population sizes of each of the strains were exposed to copper concentrations in the range: 0, 20, 40 60, 80 and 100 ppm in either Yeast - extract Mannitol Broth or in modified Leonard Jar assemblies or potted soil. Most Probable Number (MPN) studies were also done to estimate populations of the native strains of the fast - and slow - growing rhizobia in a Cu -contaminated soil. Results indicated that copper was more toxic to the slow – growing bradyrhizobia than to the fast – growing rhizobia. Reduction in population sizes in vitro was more significant (p = 0.05) for bradyrhizobial than for rhizobial strains. Reductions in fresh nodule volume, fresh nodule mass and total shoot nitrogen were more significant (p = 0.05) in the bradyrhizobial – than in rhizobial – legume associations. Copper depressed the populations of slow – growing strain CP 1 and GM 8 in vivo more than those of the fast – growing strains PV 1 and PV 2 . There was no statistically significant (p = 0.05) effect of 82.5 mg Cu/kg soil on numbers (MPN) of native rhizobial strains, probably due to adsorption of Cu by soil colloids. This study showed that based on the solution culture, potted soil and soil survival experiments, slow - growing rhizobia were more susceptible to Cu toxicity than were the fast - growing rhizobia.
Utilization of sisal bole juice - inulin as an Alternative chemical feedstock in citric acid Production
(University of Dar es Salaam, 2010) Ngonyani, Consolatha Joachim
Tanzanian Sisal industry is characterised by a severe biomass production for wastage that is (2:98) product to waste ratio. Among the waste, 100% of plant residues in a form of sisal boles, that are made of hydrolysable-fermentable sugars are slashed and burned thus causing environmental emission concerns. The present study on utilization of sisal bole juice-inulin as an alternative chemical feedstock in citric acid production was divided into three parts. The first part involved the isolation and characterisation o f the Aspergillus niger fungal strains generic to sisal boles for citric acid production using sisal inulin hydrolysate-fructose. A high biodiversity of microorganism with industrial potential were isolated and identified, including the best performer A. niger (BYF KT) fungal strain which was used in citric acid fermentation studies. The second part involved the extraction and hydrolysis of inulin sugars from sisal boles. HPLC analysis revealed that sisal boles had total sugar concentrations values between (26.4±0.24 and 26.9±0.31 g/lOOml) with the corresponding fructose values between (24.9±0.02 and 25.6±0.03 g/lOOml). Hydrolysis experiments were performed by cooking at temperature range of 30-132°C and pH range of 2-5. The effects of initial conditions (pH and temperature) were evaluated using 22 full factorial design (FFD), with varying levels of pH and temperature. The factorial fit and the analysis of variance (ANOVA), indicated that initial conditions for both pH and temperature significantly affected hydrolysates-fructose yield, at confidence interval (CI) of 95%. The optimum hydrolysates yields value of 97.2% (82.4%- fructose) was obtained by cooking at temperature 110±5°C ~ (115°C) and pH 3. The third set of experiments involved 101 pilot scale fermentation of sisal inulin- hydrolyisates-fructose using A. niger (BYF KT) generic to sisal, at initial fructose concentration range of 102-203 g/1, pH range 2-5 and nutrients additives values coded between -1 and 1. The effects of initial hydrolysate-fructose concentration, pH and nutrients additives were evaluated using a 23 full factorial design (FFD), with varying levels of initial hydrolysates-fructose concentration, pH and nutrients additives; The factorial fit and (ANOVA) for citric acid yield, indicated that initial hydrolysate-fructose concentration and pH significantly effected citric acid yield, at confidence interval (CI) of 95%, while nutrients additives was not significantly affecting the yields. Results for pilot scale fermentation of 203g/l sisal juice hydrolysate-fructose, in absence of nutrients additive and pH 5 produced highest yields value of 46.66% (103.15±13.08 g/1). On the contrary, minimum citric acid yield value of 9.51% (9.70±2.40 g/1) was obtained at low initial fructose concentration of 102 g/1, pH 2 and with nutrient additions. The current findings supported that sisal inulin has a great potential use as an alternative feedstock in citric acid production, adding value to sisal industry and could be one way of dealing with waste management.

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