Browsing by Author "Semu, E"

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Contents of heavy metals in coal and its by-products from the Songwe-Kiwira Mine, Tukuyu District, Tanzania
(SADC Project, 2010) Mndeme, U. M.; Semu, E
Coals can be potent sources of heavy metal pollution upon their mining and utilisation. While Tanzania has many coal deposits, the coals have not been evaluated to determine their heavy metal contents and their potential to cause environmental pollution. Therefore, a study was undertaken to determine the heavy metal contents of the coal and its by-products from the Songwe-Kiwira mine, Tukuyu district, southern Tanzania. This is the area in the country where, currently, coal is being mined. The contents of lead (Pb), copper (Cu), chromium (Cr), cadmium (Cd), zinc (Zn), selenium (Se), and manganese (Mn) in different coal grades, in coal combustion by-products, and in various coal-derived sediments were determined by atomic absorption spectrophotometry (AAS) following aqua-regia digestion. The results showed the presence of heavy metals in the Kiwira coal. The highest levels of metals recorded in the different grades of coal were 6.8, 4.7, 7.9, 35.1, 72.4, 58.9, 59.5 and 801.1 mg/kg for Cr, Ni, Cd, Pb, Zn, Cu, Se and Mn, respectively. Long-term disposal of these coals will result in pollution of the surrounding environment. Some metal (Zn, Cr, Mn, Pb, Cd) levels in the coal indicated significant (p = 0.05) differences with coal sampling periods, an indication that the metal contents of the Kiwira coal were not uniform along the coal seams or layers. The highest levels in the solid ash were 6.4, 5.2, 9.4, 33.3 and 60.4 mg/kg for Cr, Ni, Cd, Pb and Se, respectively. The highest levels for the fly ash were 7.1, 4.5, 10.8, 90.9 and 45.4 mg/kg, for Cr, Ni, Cd, Pb and Se, respectively. Long term accumulation of these metals will cause environmental pollution. Results showed variations in metal contents between the coal grades, its combustion by-products as well as between the sampling periods.
Fertility of soils cropped to rice (oryza sativa, L.) in Eastern Same District, Kilimanjaro Region, Tanzania.
(UNISWA Journal of Agriculture, 2006) Amur, N.; Semu, E
Decline in soil fertility has been found to be the main cause of low rice yields in many soils of Tanzania. The objective of this study was to evaluate the effects of N, P, K and Zn on their uptake by lowland rice (Oryza sativa, L.) grown in nutrient-deficient soils of Same district. Three bulk soil samples, which were low in some macro- and micro-nutrients, were collected from Kisiwani, Ndungu and Kihurio, and used for pot experiments. The response of rice (Oryza sativa, L., cv super SSD5) to N, P, K and Zn was assessed in a glasshouse experiment where plants were grown for 56 days. Plant samples were analysed for N, P, K, Ca, Mg, Zn and Fe after digestion with HNO 3-H20 2. The results showed that N, P and K increased uptake of each mineral nutrient by rice plants, in all the soils used. For example, N alone increased N uptake from 5.8 to 28.4, 8.3 to 37.0, and 3.6 to 14.2 mg/plant in Ndungu, Mbugani and Kimunyu soils, respectively. Zinc, in addition to N, P, and K, increased the nutrient uptake even further. The uptake of each nutrient applied was consistent with the increase in dry matter yields and nutrient concentrations in rice shoots reported earlier. It was thus confirmed that these soils were deficient in N, P and Zn. Iron was required in the Kisiwani (Mbugani) soils, which were severely deficient of this element.
Maize yield response and nutrient uptake after micronutrient application on a volcanic soil
(American Society of Agronomy, 2006-07-12) Lisuma, Jacob B; Semoka, J. M. R; Semu, E
Micronutrients, which are often deficient in volcanic soils, together with macronutrients may lead to higher yields in these soils. A study was conducted under pot and field conditions to identify and correct some micronutrient constraints in a volcanic soil at Mpangala, Tanza- nia, for optimization of maize (Zea mays L.) yields. Dry matter (DM) yields, plant B, Cu, and Zn concentrations, plant B, Cu, and Zn uptake, and grain yields were used to assess the effects of micronutrient treatments. In pots, B, Cu, and Zn fertilizers were applied separately to the soil at two levels, 0 and 2 mg B kg 21 , 0 and 5 mg Cu kg 21 , and 0 and 10 mg Zn kg 21 , in combination with constant rates of 240 mg N kg 21 or 160 mg P kg 21 fertilizers. A higher rate of 320 mg P kg 21 was also included to assess the adequacy of the basal P rate used. A second pot study attempted to establish an optimum rate of Cu under glass- house conditions; rates ranging from 0 to 20 mg kg 21 Cu were tested. Copper significantly (P 5 0.05) increased both maize DM and grain yields; the estimated optimum rate was 20 mg Cu kg 21 under glass- house conditions. This high rate is thought to be due to the high Cu- fixation capacity of volcanic soils. Boron and Zn were sufficient for normal plant growth. We conclude that maize production can be in- creased considerably in Mpangala and other similar soils in the same agroecological zone by applying N, P, and Cu at rates of 120, 80, and 10 kg ha 21 , respectively.
Pedological characterization, fertility status and classification of the soils under maize production of Bako Tibe and Toke Kutaye Districts of Western Showa, Ethiopia
(2016) Abera, T; Wegary, D; Semu, E; Msanya, B. M.; Debele, T; Kim, H
Maize farm fields were selected in two districts of western Showa, Ethiopia. Four representative maize fields were selected based on landforms and other physiographic attributes in humid highland and sub humid mid altitude areas of Toke Kutaye and Bako Tibe Districts. The objective was to characterize and classify the soils under maize production in Toke Kutaye and Bako Tibe Districts of western Showa, Ethiopia. Four soil profiles were opened and characterized. Pedons are formed under udic and perudic moisture and iso-thermic temperature regimes for both districts. The soils were very deep, well-drained reddish brown to dark reddish brown loamy sand to sandy clay loams, with thick reddish brown loamy sand top and sub soil for Bako Tibe and Toke Kutaye. Three pedons had clayey top and sub soils. The pH of surface soil ranged from 4.48-5.52 which was very strongly acidic to strongly acidic. The soil organic carbon contents of the topsoil and subsoil of the four pedons ranged from 2.07 to 2.69% and 0.35 to 2.85 %, which were rated as medium to high, but very low to high respectively. Both two highland pedons had CEC ranging from 20.06 to 54.17 cmol c kg -1 soil, which was rated as medium to very high, while in the two mid altitude pedons it ranged from 10.82 to 23.52 cmol c kg -1 soil CEC, which was low to medium. The total nitrogen levels ranged from 0.19 to 0.23% for topsoils, which was low to medium, and from 0.03 to 0.07 % for subsoils, which was very low. According to USDA Soil Taxonomy, the four pedons were classified as Typic Palehumults (Acrisols and Alisols according to WRB). The four pedons were different in physicochemical properties, indicating the need to characterize soils to give site-specific fertilizer recommendations for maize production.
Preliminary characterization of some streptomyces species from four Tanzanian soils and their antimicrobial potential against selected plant and animal pathogenic bacteria
(World Journal of Microbiology & Biotechnology, 2000-05-02) Ndonde, M. J. M; Semu, E
This study was undertaken to characterize Streptomyces strains occurring in some soils of Tanzania as well as to evaluate their potential to synthesize antimicrobial compounds. Six main classes of isolates were observed according to the colour of aerial mycelium. These were gray, cream, blue, pink, red, and white. The gray colour class dominated. About 65% of the isolates produced soluble pigments of various colours while about 33% of the isolates did not produce any soluble pigments. Brown coloured soluble pigments dominated. About 57% of the isolates had spiral spore chains. Some Streptomyces isolates displayed strong (>30 mm inhibition zone), moderate (20±30 mm), or weak (<20 mm) antibiosis against the plant/animal pathogenic bacteria tested. Other isolates did not show any antibiosis against any of the test pathogens. The plant pathogens CMM IPO 542 (Clavibacter michiganensis ssp. michiganensis) and Xanthomonas vascatoria were inhibited by most of the Streptomyces isolates. Xanthomonas oryzae pv. oryzae and X. campestris were inhibited by the least number of the Streptomyces isolates. Most of the animal pathogens tested seemed to show resistance to the antibiotics produced by some of the Streptomyces isolates which had shown high activity against the plant pathogens.