Browsing by Author "Semu, E."

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Chemical properties of travertine from different sources in Rwanda with regards to their calcium oxide and magnesium oxide contents
(Sokoine University of Agriculture, Tanzania.) Sirikare, N.S.; Naramabuye, F.X.; Marwa, E; Semu, E.
Contents of heavy metals in coal and its by-products from the Songwe-Kiwira Mine, Tukuyu District, Tanzania
(SADC-ICART Project) Mndeme, U.M.; Semu, E.
Contents of heavy metals in coal and its by-products from the Songwe-Kiwira Mine, Tukuyu District, Tanzania
(SADC-ICART 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.
Contribution of legume rotations to the nitrogen requirements of a subsequent maize crop on a rhodic ferralsol in Tanga, Tanzania
Marandu, A. E. T.; Semu, E.; Mrema, J. P.; Nyaki, A. S.
Contribution of legume rotations to the nitrogen requirements of a subsequent maize crop on a rhodic ferralsol in Tanga, Tanzania
(2013) Marandu, A. E. T.; Semu, E.; Mrema, J. P.; Nyaki, A. S.
Industrial fertilizers are expensive for small-scale farmers who, as alternative, rely on legume crops for providing N for a subsequent maize crop. A legume-maize rotational experiment was carried out on a Rhodic Ferralsol at Mlingano Agricultural Research Institute in Muheza, Tanga, Tanzania, to evaluate the effects of legumes rotation in meeting the N fertilizer requirements of maize. The experimental site was located at 39o 52’E, 5o 10’S and 183 metres above sea level (m.a.s.l.). The experiment was conducted for two rotation cycles whereby cowpea, pigeonpea or greengram were grown during the short rains followed by maize during the long rains. The maize rotations were imposed on plots on which legumes had been grown during the previous legume rotation. Monoculture maize was grown with treatments of 0, 25, 50 and 100 kg N ha-1 imposed for purposes of plotting N fertilizer response curves. Based on the response curve lines, the effects of the legume rotation on maize yields were compared and translated as N fertilizer equivalency of the legumes in question. The grain and residue yields of the three legumes were significantly different (P<0.01), a fact which was attributed to the genetic differences of the legume species. The maize yields following rotation with each of the three legumes were significantly higher (P<0.05) than those under continuous maize. The effects of the rotations on increasing the maize yields were equivalent to application of 25, 19 and 16 kg N ha-1 for the cowpea, pigeonpea and greengram rotations, respectively. It was, however, concluded that the contributions of N by the legumes in the legume-maize rotations were not enough to satisfy the maize N requirements of 50 kg N/ha; hence supplementation with mineral N, in addition to the rotations, is necessary for increased yields.
Cyanosoils project site and soil characterization
(Sokoine University of Agriculture) Msanya, B. M.; Kimaro, D. N.; Maliondo, S. M. S.; Semu, E.; Madoffe, S. S.; Mvena, Z. K. S.
Cyanosoils project site and soil characterization
(Sokoine University of Agriculture, 2002) Msanya, B. M.; Kimaro, D. N.; Maliondo, S. M. S.; Semu, E.; Madoffe, S. S.; Mvena, Z. K. S.
The objective of the study was to select sites for the Cyanosoils project and to characterize the soils on which experiments will be carried out. Through field visits and studies three sites were identified and described in Morogoro Urban and Mvomero Districts. Soil profiles were excavated, described and sampled for laboratory analyses.
Effects of elevated copper levels on biological nitrogen fixation and occurrence of rhizobia in a Tanzanian coffee-cropped soil
(Sokoine University of Agriculture) Tindwa, H.; Semu, E.; Msumali, G. P.
Effects of elevated copper levels on biological nitrogen fixation and occurrence of rhizobia in a Tanzanian coffee-cropped soil
(Sokoine University of Agriculture, 2014) Tindwa, H.; Semu, E.; Msumali, G. P.
A study was conducted to investigate the effects of increasing copper concentration in soil on rhizobial occurrence and the process of biological nitrogen fixation. Two slow-growing bradyrhizobial strains CP, and GM, and two fast-growing rhizobial strains PV, and PV2 were studied by comparing their performance under increasing copper concentrations in greenhouse-based assays involving modified Leonard jar assemblies and potted-soil experiments. Additionally, field samples from soils grown to coffee and subjected to long-term use of copper-based fungicides were analyzed for their total indigenous rhizobial populations using the most probable number-plant infection technique. Results indicated that elevated copper levels in the growth medium had inhibitory effects on nodulation, biological N2 fixation and overall rhizobial numbers in soil. Significant (p= 0.05%) reductions in fresh nodule mass, fresh nodule volume and total shoot nitrogen were recorded when copper concentration was increased from 0 to 100 ppm in both modified Leonard jar assemblies and potted-soil trials. Effective decrements in all the three parameters of fresh nodule mass, fresh nodule volume and total shoot nitrogen were more pronounced with the slow-growing bradyrhizobial strains of CP, and GM, than with the fast-growing PV, and PV2. The MPN-plant infection technique results showed a non-significant (p=0.05) but substantial decrement in rhizobial and bradyrhizobial numbers when the copper-contaminated field soil (82.5 mgCu/g soil) was compared to a control soil (1.8 mgCu/g soil). The study concludes, therefore, that elevated levels of copper in soil could be harmful to free-living rhizobia and their abilities to fix N2 in respective symbiotic associations with legume species. Such negative effects were more pronounced in the slow-growing bradyrhizobial than rhizobial species used.
Effects of Kocide 101® on the bean (Phaseolus vulgaris, L.) - Rhizobium symbiosis
(Acta Agriculturae Scandinavica, Section B — Soil & Plant Science) Baijukya, F. P.; Semu, E.
Effects of Kocide 101® on the bean (Phaseolus vulgaris, L.) - Rhizobium symbiosis
(Acta Agriculturae Scandinavica, Section B — Soil & Plant Science, 1998) Baijukya, F. P.; Semu, E.
A glasshouse study was undertaken to investigate the effects of the copper fungicide Kocide 101 and its residues in soil on the growth. nodulation and nitrogen fixation of beans (Phaseolus iulgaris, L.). The soil used was a sandy clay loam classified as Typic Rhodustalf. The bean variety SUA 90 was used as test crop. The bean rhizobia strains CIA T 899, PV1 and a local isolate were used. Kocide 101 applied at the recommended rate (equivalent to 1.7 mg kg-I soil) had no significant negative eff ects on the growth. nodulation or nitrogen fixation of bean plants. Higher levels of Kocide 101 significantly (P < 0.05) reduced plant growth, nodulation and nitrogen fixation.The bean plants inoculated with the "local isolate" rhizobia had the highest dry matter weights. nodule numbers and nodule dry weights,and also had more N fixation. They were followed by those inoculated with the PV1 strain and. lastly, those inoculated with CIA T 899.The growth and nodulation of bean plants were still curtailed by the Kocide 101 residues four months after the fungicide was first applied to the soil. Therefore, occurrence of high levels of Kocide 101 in soils can have long-term effects on the performance of the bean-rhizobia symbiosis.
Evaluation of the soil fertility status in relation to crop nutritive quality in the selected physiographic units of Mbeya Region, Tanzania
(RUFORUM Biennial Meeting) Amuri, N.; Semu, E.; Msanya, B. M.; Mhoro, L.; Anthony, J. M.
Evaluation of the soil fertility status in relation to crop nutritive quality in the selected physiographic units of Mbeya Region, Tanzania
(RUFORUM) Amuri, N.; Semu, E.; Msanya, B. M.; Mhoro, L.; Anthony, J. M.
Evaluation of the soil fertility status in relation to crop nutritive quality in the selected physiographic units of Mbeya Region, Tanzania
(RUFORUM, 2010-09) Amuri, N.; Semu, E.; Msanya, B. M.; Mhoro, L.; Anthony, J. M.
This study is assessing soil fertility status in Mbeya region of Tanzania in terms of adequacy for crop growth and crop nutrient status in terms of human nutrition. It will examine levels of macro and micronutrient. The study has just been initiated and will run for two years.
Evaluation of the soil fertility status in relation to crop nutritive quality in the selected physiographic units of Mbeya Region, Tanzania
(RUFORUM Biennial Meeting, 2010-09) Amuri, N.; Semu, E.; Msanya, B. M.; Mhoro, L.; Anthony, J. M.
This study is assessing soil fertility status in Mbeya region of Tanzania in terms of adequacy for crop growth and crop nutrient status in terms of human nutrition. It will examine levels of macro and micronutrient. The study has just been initiated and will run for two years.
Fertility of soils gropped to rice (oryza sativa, l.) in eastern Same District, Kilimanjaro Region, Tanzania
(Sokoine University of Agriculture, Tanzania.) Amur, N.; Semu, E.
Growth and yield responses of rice, wheat and beans to Zn and Cu fertilizers in soils of Mbeya region, Tanzania
(International Journal of Agricultural Policy and Research) Mhoro, Lydia; Semu, E.; Amuri, N.; Msanya, B. M.; Munishi, J. A.; Malley, Zacharia
Growth and yield responses of rice, wheat and beans to Zn and Cu fertilizers in soils of Mbeya region, Tanzania
(International Journal of Agricultural Policy and Research, 2015-11-10) Mhoro, Lydia; Semu, E.; Amuri, N.; Msanya, B. M.; Munishi, J. A.; Malley, Zacharia
Low crop production in most arable lands is associated with soils highly depleted of nutrients. A study was conducted in selected physiographic units of Mbeya Region Tanzania, to investigate the levels of soil macro- and micronutrients effect on crops (rice, wheat and beans) performance. Soils were analyzed in the laboratory. Screen-house experiments with three levels of Zn (0, 7.5 and 15 mg kg -1 soil) and Cu (0, 5 and 10 mg kg -1 soil) in combination with N and P treatment in completely randomized design with three replications was conducted. The results showed that all soils were deficient in N, P and Cu, while 46% of soils had low Ca. Zn was low in 46% of the soils while K and Fe was sufficient in all soils. Application of 15 mg kg -1 Zn and 5 mg kg -1 Cu with N and P fertilizers gave significantly highest grain yield of rice (9.05 g pot -1 ), beans (5.80 g pot -1 ) and wheat (5.58 g pot -1 ). The control gave lowest grain yield in all crops. Zink rate of 15 mg kg -1 and Cu rate of 5 mg kg -1 was sufficient to increase yields in these soils. Field experiments are recommended to confirm Zn and Cu fertilizer recommendations.
Heavy metal contents of some soils of tomato growing fields in Hai district, Tanzania, as influenced by duration of use of metal-containing fungicides
Munisi, N.; Semu, E.
Heavy metal contents of some soils of tomato growing fields in Hai district, Tanzania, as influenced by duration of use of metal-containing fungicides
(2001) Munisi, N.; Semu, E.
Hai district is one of the major vegetable producing areas of Tanzania. Copper fungicides have been used for a long time in the district, but no studies have been conducted to evaluate accumulation of Cu in the soils in that district. This study was, therefore, initiated-to survey and-to document the status of fungicide use in some tomato fields. Generally, the total or DTPA extractable Cu contents were significantly (P < 0.05) higher in fungicide-treated, soils than in control soil, the levels reaching 7305 mg total Cu/kg soil where fungicides have been used for 15 to 30 years (long-term use). The total and extractable Cu contens of the soils increased with increasing duration of Cu fungicide use. This resulted in lower microbial populations with increasing duration of fungicide use, the populations decreasing from log10 = 6.4 in control soils to log10 = 5.1 in long-term use soils, Zinc and manganese did not show clear trends. There was no significant relationship between total or DTPA-extractable Cu, Zn or Mn and soil pH. Total Cu was significantly and positively correlated with organic carbon, while total Mn was significantly but negatively correlated with organic carbon. It is conclud that long-term use of Cu fungicides in Hai district has resulted in a build-up of Cu residues in the soils, and this may impair microbial processes in those soils.