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., 2012) Sirikare, N.S.; Naramabuye, F.X.; Marwa, E; Semu, E.
This study was conducted in the districts of Rusizi, Korongi and Musanze districts, Rwanda in areas where travertine is found. The objective of the study was to characterize the chemical compositions of travertine for use in amending soil acidity for crop production. Thirty two samples of travertine from different deposits at Mashyuza (Rusizi), Gishita (Karongi) and Mpenge and Rwaza (Musanze) were analysed to establish their CaO and MgO contents. Percentages by weight of CaO and MgO in samples were determined using X-ray fluorescence. Results revealed that travertine from Mashyuza and Rwaza has the highest CaO wt% content followed by Gishyita. Mpenge deposits had the lowest content CaO% . There was no significant difference among sites for MgO contin travertine. The tratio of CaO:MgO in Mpenge, Mashyuza and Gishita was within a range required to prevent deficiency of Ca and Mg in acid soils where maize and beans are grown.
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
(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, 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, 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, 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, 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, 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., 2006) Amur, N.; Semu, E.
Decline in soil fertility has been found to be the main cause of low rice (Oryza sativa L.) yields in many soils cropped to rice in Tanzania. The objective of this study was to evaluate the effects of N, P, K and Zn on shoot dry matter (DM) yields of lowland rice plants grown in some soils of Same district. Three bulk soil samples were collected from Kisiwani (Mbugani), Ndungu and Kihurio (Kimunyu), which were found to be deficient in some macro- and micro-nutrients following laboratory soil analysis, and were used for this pot experiment. The responses of rice 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 results showed that N, P and K increased rice shoot DM yields in all the soils used, from 0.61, 0.74 and 0.47 in the controls to 3.01, 2.76, and 1.57 g/plant in the highest N:P:K treatments in Ndungu, Mbugani and Kimunyu sites, respectively. It was further revealed that Zn supplementation in addition to NPK also increased rice dry matter yields further, from 3.05, 2.73 and 1.42 in the Zn controls to 4.75, 4.44, and 2.16 g/plant in the 15 kg/ha Zn treatments in Ndungu, Mbugani and Kimunyu sites, respectively. Iron (Fe) was also found to be deficient in Mbugani soils, and Fe supplementation improved plant growth. It is concluded that deficiency of these nutrients was probably a widespread problem in these and other soils cropped to rice in the district.
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
(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.
Influence of farm yard manure, poultry manure and forest litter on copper solubility in soil and uptake by Phaseohrs vulgaris
(British Society of Soil Science, 2014-12) Senkondo, Y. H.; Tack, F. M. G.; Semu, E.
Long term and intensive use of copper-based fungicides on coffee farms may contaminate soils with copper. The legacy of copper pollution may pose the risk of contaminating food crops cultivated on these soils. A randomized block design field experiment at Kilimanjaro, Tanzania was designed to investigate the effects of different application rates of cattle manure, poultry manure and forest litter on aqua regia, EDTA and CaC12 extractable copper in soils and copper uptake by bean plants grown on this long-term copper-contaminated soil (more than 50 yr of copper application). It was important to examine the potential of the organic amendments in mobilizing or immobilizing copper and assess the risks of contaminating bean crops at a farm, where the application of organic amendments was common practice. At harvest, rhizosphere soils were collected and analysed. The soils were found to have large concentrations of copper, greatly exceeding international standard levels. Poultry manure applied at 40 tons/ha significantly increased CaC12 extractable copper compared with the control treatment. Organic carbon, cation exchange capacity, EDTA extractable copper, aqua regia extractable copper and copper concentrations in bean seeds or leaves were not significantly changed by the organic matter treatments. The concentration of copper was significantly less in bean seeds than in bean leaves (P < 0.01). The bean plants did not take up excessive quantities of copper, and therefore, the risk of copper contamination of bean crops in this farm appears to be small.
Liming and sulfur amendments improve growth and yields of maize in Rubona Ultisol and Nyamifumba Oxisol
(Taylor & Francis, 2015-07-27) Sirikare, N. S.; Marwa, E. M.; Semu, E.; Naramabuye, F. X.
Aluminum toxicity is a major limitation to crop production on highly weathered and leached soils in Rwanda. Moreover, sulfur though widely deficient in Rwanda acidic soils has received little attention by soil fertility researchers. A field experiment on maize response and soil nutrients status to liming materials of travertines at 3.4 t ha-I , ash wood 1.2 t ha-I of CaO equivalent and sulfur at 10 kg ha-1 combined with NPK at 80, 60, and 45 kg ha-I respectively was conducted in Rubona Ultisol and Nyamifumba Oxisol. Results revealed that travertine and wood ash increased the soil pH from 4.7 to 5.8 or higher and decreased exchangeable Al3+ and H+ to near 0 cmolc kg-1. Soil nutrients generally increased to high or medium ranges for crop production. Leaf dry biomass, plant height and maize grain yields were significantly higher in Rubona Ultisol than in Nyamifumba Oxisol. Plots that received wood ash, with NPKS or with NPK, generally had higher maize yields, followed by those which received travertines and NPKS or NPK which had maize growth response as compared to the control plots which received NPK only. Thereby, a combination of wood ash with NPKS or NPK, travertines with NPKS was found to neutralize soil aluminum toxicity, increase soil nutrients status to required levels for plant growth and increase maize yields significantly.
Morphology, genesis, physico-chemical properties, classification and potential of soils derived from volcanic parent materials in selected districts of Mbeya region, Tanzania
(International Journal of Plant & Soil Science, 2016-03-30) Msanya, B. M.; Munishi, Juvenal, A.; Amuri, N.; Semu, E.; Mhoro, Lydia; Malley, Zacharia
This study clarifies the morphology, genesis, physico-chemical properties and classification of soils developed from volcanic parent materials of Mbeya Region, Tanzania. Six typical pedons (MWK 01, IFIG 02, MKY 03, MWZ 04, KYE 01 and NDE 01), were identified, described and 33 soil samples analyzed for physical and chemical characteristics. Results indicate that all pedons were very deep, with textures ranging between fine and coarse. Soil moisture retention ranged between low and medium (78 - 101 mm/m). Some pedons had volcanic ash layers of varying thicknesses and buried 2BC, 2Bwb or 3Bwb horizons, typical of recent volcanic soils. Topsoils had low bulk and particle densities ranging between 0.70 to 1.26 g cm -3 and 1.95 to 2.55 g cm -3 , respectively. Organic carbon (OC) content ranged from medium to very high (1.29 to 5.58%). The studied pedons had extremely acidic to very slightly acidic pH ranging from 4.02 to 6.58. Cation -1 exchange capacity (CEC) ranged from medium to very high (16.8 - 41 cmol(+) kg soil for -1 topsoils and 21 - 42.6 cmol(+) kg for subsoils). All studied pedons had pH NaF > 9.5, reflecting an exchange complex dominated by amorphous Fe and Al oxides and/or humus complexes. Phosphate retention capacity (PRC) ranged from 25 to 97% and one pedon (MWZ 04) met the andic properties requirement of PRC ≥ 85%. SiO 2, Al 2 O 3 and Fe 2 O 3 ranged from 46.5 to 62.1%, 26.3 to 38.4% and 4.0 to 9.8%, respectively. On the basis of computed Chemical Index of Alteration (CIA), the degree of weathering of the studied pedons followed the trend NDE 01>MKY 03>MKW 01>KYE 01>IFIG 02>MWZ 04. According to USDA Soil Taxonomy, the studied pedons were classified as Alfisols (pedons MKW 01, MKY 03 and NDE 01), Inceptisol (pedon IFIG 02), Andisol (pedon MWZ 04) and Entisol (Pedon KYE 01), respectively correlating to Alisols, Cambisol, Andosol and Umbrisol of WRB for Soil Resources. The studied soils were generally rated as having low to medium fertility.
Pedological characteristics and implication on soil fertility of selected soils of Mbeya Region, Tanzania
(RUFORUM, 2012-09) Amuri, N.; Mhoro, L.; Munishi, J. A.; Msanya, B. M.; Semu, E.; Malley, Z.
Understanding the soil origin and its fertility in a given climatic conditions is important for efficient and sustainable utilization of soils. The composition of parent material determines the mineral nutrient content (Nube and Voortman, 2006), and sorption of nutrients, other chemicals and soil organic matter. A recent study in China demonstrated that available Fe and Zn in Xichang city soils differed depending on the nature of the parent rock (Zhang et al., 2012). Time is also essential in determining the stage of weathering, and hence soil properties. The soils of the surveyed areas are derived from volcanic tephra deposits of which are reported to be from relatively old (Upper Miocene to Lower Pleistocene Kitulo and Ngozi volcanoes) to most recent eruptions (Middle Pleistocene to Holocene Rungwe and Kyejo Volcano) (Fontijn et al., 2010). Information on the differences in chemical and other characteristics of the soils derived from these chronologically variable deposits of the area is limited. Mbeya region is among the four regions of Southern Highlands of Tanzania with high agricultural production, supplying major staple food in the country. However, crop yields are still low despite use of NPK fertilizers, contributing to food insecurity in Tanzania. Copper and Zn deficiencies were reported in this area’s volcanic soils about three decades ago, which was associated with nutrient mining (Kamasho, 1980). Yet, to date there is no follow-up studies on the status of these micronutrients in soils. Therefore, there is a need to determine the properties of soils of Mbeya region in relation to their origin and genesis. Mineral malnutrition is also wide spread and it is estimated that about 66% of world population is Fe deficient, over 30% is Zn deficient, 30% is iodine deficient and 15% is selenium deficient (White and Broadley, 2009). In Tanzania about 65% of children under 5 years of age are iron deficient (Fortifying African’s Future, 2009), 58.2% of pregnant women are anemic and 23% of the population are at risk of Zn deficiency (TFNC, 2009). These nutritional health problems can be attributed to low soil mineral content and/or availability to crops (Welch and Graham, 2002). Adequate levels of essential minerals in food crops to satisfy human health requirement is referred to as crop nutritive quality. One way to curb mineral malnutrition is fortification of some staple food with these essential minerals. However, food fortification cannot be expected to reach all populations deficient in essential micronutrients, especially in developing countries, and have challenge of low bioavailability (Hurrell, 1997; Mehasho, 2006). Therefore, there is a need to investigate, systematically, the relationship between soil nutrient contents (both macro- and micro-nutrients) and crop quality as might be related to the potential for agronomic biofortification to improve human nutrition and health. This study was therefore conducted as a contribution to efforts by national and international programs and strategies to attain not only high yields but also nutritional health for poverty alleviation. Therefore, the objective of this study was to determine and assess the pedologicalcharacteristics of soils and their influence on soil fertility and crop quality in selected physiographic units of Mbeya region. Specifically, i) to determine the morphological and physico-chemical characteristics of the soils ii) to determine the mineralogical composition of the soils iii) to determine the extent of weathering, and iv) to determine the implication of soil characteristics on nutrient availability, agricultural productivity and crop nutritive quality.
Pedological characterization and classification of some typical soils in three agro-ecological settings of South-Eastern Tanzania
(IJSER, 2018-02) Tenga, J. J.; Msanya, B. M.; Semoka, J. M.; Semu, E.; Mwongo, S. B.
This study was carried out in South-Eastern Tanzania to establish representative experimental sites on the basis of agro- ecological settings and soils. Three pedons were characterized namely NWJ-P1 in Nawaje village, MKG-P1 in Mikangaula village and NNL-P1 in Nannala village. Soil moisture and temperature regimes in the study areas were, respectively, ustic and isohyperthermic. Fifteen soil samples from genetic soil horizons were analyzed for physico-chemical properties. Pedons NNL-P1 and MKG-P1 had loamy sand topsoils overlying sandy loam to sand clay loam subsoils. Pedon NWJ-P1 had sandy clay loam topsoil overlying clay subsoil with indications of eluviation-illuviation as dominant pedogenic process. Whereas pedons NWJ-P1 and MKG-P1 were medium acid to slightly acid (pH 5.91 - 6.35), pedon NNL-P1 was extremely to very strongly acid (pH 4.36 - 4.57). Topsoil OC contents of the soils were very low to medium (0.49 to 1.28%) while subsoil values were very low to low (0.16 - 0.66%). Total nitrogen in the pedons were very low (0.02 - 0.07%) while C/N ratios generally ranged from 7 to 18 indicating good to moderate quality of soil organic matter. All studied soils were low in -1 -1 available P (< 7 mg kg ) except topsoil of pedon NNL-P1 which had medium values (P range 7- 20 mg kg ). CEC values ranged from very -1 -1 low (< 6.0 cmol (c) kg ) to low (6.0 - 12.0 cmol (c) kg ). % base saturation of pedon NNL-P1 was medium (21 - 60) while pedons NWJ-P1 and MKG-P1 had high values (> 60%). Nutrient ratios Ca/TEB, Mg/K and %( K/TEB) indicated some degree of nutrient imbalance in the soils likely to impair nutrient availability to plants. According to USDA Soil Taxonomy the pedons classified as Typic Dystrustepts (pedon NNL- P1), Typic Argiustolls (pedon NWJ-P1) and Typic Haplustepts (pedon MKG-P1) which, according to WRB for Soil Resources, translated into Dystric Cambisols, Luvic Phaeozems, and Eutric Chromic Cambisols, respectively. In view of the study results, the studied pedons differed markedly in terms of pedological and physico-chemical properties, emphasizing the need to characterize soils before embarking on strategies and practices on soil fertility management for enhanced sustainable agriculture production. Sustainable cropping on the studied soils could be achieved with introduction of technologies suitable for rejuvenating soil fertility such as manuring, crop rotation, proper management of crop residues, fallow periods, introduction of leguminous cover crops in the farming system and use of fertilizers, particularly non-acidifying types of fertilizers.
Pedological characterization of typical soils of Dodoma Capital City District, Tanzania: soil morphology, physico-chemical properties, classification and soil fertility trends
(Isaac Scientific Publishing, 2018-11-04) Msanya, B. M.; Mwasyika, T. A.; Amuri, N.; Semu, E.; Mhoro, L.
Pedolological characterization was done in Dodoma Capital City District, Tanzania. Three soil profiles developed from in-situ weathering of granic rocks and designated as HIS-P1, HIS- P2 and HIS-P3 were described. Fifteen samples were taken from genetic horizons and analyzed for physical and chemical characteristics. The soils were generally very deep, with varying textures. Whereas profile HIS-P2 was dominantly loamy, profiles HIS-P1 and HIS-P3 were both clayey but the latter had heavy clay type. In profile HIS-P1, clay eluviation-illuviation was a dominant pedogenic process manifested by presence of clay cutans in the subsoil. Profile HIS-P2 displayed redoximorphic features due to fluctuating water table. Shrinking and swelling, and argilli-pedoturbation were typical pedogenic processes in profile HIS-P3. Profile HIS-P1 had more developed structure (subangular blocky) followed by HIS-P3 and lastly profile HIS-P2 which was structureless massive breaking into weak subangular blocks. Whereas topsoil bulk density values of the soils were within acceptable range, subsoil BD values are likely to cause problems of root penetration particularly for deep rooted crops. Profiles HIS-P1 and HIS-P3 may present limitations to crop growth due to high pH values (> 7.5) in the subsoil which may limit availability of plant nutrients e.g. phosphorus. Organic carbon and nitrogen were generally low and very low in all profiles with most values being < 1.25% and < 0.10%, respectively. Availabe P values were low to very low (< 7 mg/kg) throughout the three profiles. Topsoil base saturation values were high (> 50%) in profiles HIS-P1 and HIS-P2 but very high throughout proflie HIS-P3 (83 - 118%). Zn and Fe levels were rated as inadequate for crop production. According to USDA Soil Taxonomy, the soils were classified as Typic Rhodustults (HIS- P1), Fluventic Dystrustepts (HIS-P2) and Chromic Calcitorrerts (HIS-P3) corresponding to Haplic Cutanic Acrisols, Haplic Cambisols and Calcic Mazic Vertisols in the WRB for Soil Resources. The three soils had different physico-chemical properties, hence the need to characterize soils before fertilizer recommendations is met.
Phosphorus adsorption and its relation with soil properties in acid soils of Western Kenya
(Department of Soil Science Sokoine, University of Agriculture, Tanzania., 2014-10) Muindi, E. M.; Mrema, J. P.; Semu, E.; Mtakwal, P. W.; Gachene, C. K.; Njogu, M. K
Low available phosphorus (P) is one of the major hindrances to crop production in acid soils of western Kenya. Although considerable work has been done to establish P levels in the region, there is paucity of information on which to base fertilizer recommendations due to potential crop production differences caused by different soil types and climate. Phosphorus adsorption capacity and its relationship with some soil properties were evaluated in acid soils from nine locations of western Kenya. Adsorption data was obtained by equilibrating the nine soil samples with 30m1 of KH2PO4 in 0.01 M CaCl2, containing 0, 80, 150 and 300 pg m1-1 for 48 hours with shaking for 30 minutes at intervals of 8 hours. Langmuir, Freundlich and Tempkin adsorption models were fitted to the test results and relationship between P adsorption and soil properties determined by correlations. The result of this study showed that the soils were strongly to extremely acidic (pH 4.83 - 3.76), had high exchangeable Al3+ (>2 cmol Al kg-1), Al saturation of (> 20% Al) and calculated maximal phosphorous adsorption varied from 770.83 to 1795.83 mg kg' soil. Comparing the models, Freundlich linear model showed a better fit to the tested soils compared to Langmuir and Tempkin models. The regression coefficients (R2) for the fitted Freundlich P adsorption isotherms was highly significant ranging from (0.995- 1.000) for all tested soils. Analysis of relationship between adsorption maximum and soil attributes revealed that adsorption maximum positively correlated with clay content, exchangeable P, exchangeable acidity and Aluminium saturation and negatively correlation with organic matter and electrical conductivity. Due to differences in maximal P sorption capacities within the tested area, blanket P fertilizer recommendation may affect crop productivity in some sites. There is therefore need for further research to determine optimal Phosphorus requirements for soils in each research site.
Potential of carbon storage in major soil types of the Miombo woodland ecosystem, Tanzania: A review
(Academic and Scientific Publishing, 2014-07) Shelukindo, H. B.; Semu, E.; Msanya, B. M.; Munishi, P. K. T.; Maliondo, S. M. S.; Singh, B. R.
This review was undertaken to explore the potential of soils to sequester and store large quantities of carbon (C) in the form of soil organic carbon (SOC) from the view point of global climate change regulation and reduced CO2 emissions. Miombo woodland forest soils are an important sink of atmospheric C. The major soils found in the Miombo woodlands include: Cambisols (Inceptisols), Leptosols, and Fluvisols (Entisols), Luvisols (Alfisols), Acrisols (Ultisols), Ferralsols (Oxisols), and Vertisols (FAO-WRB classification system and USDA- Soil Taxonomy). The soils differed in physico-chemical properties and exhibited differences in morphological characteristics, nutrient status and SOC storage, suggesting a remarkable variation in potential, constraints and management strategies for the different soil types. The review underscored the potential of soils as one among the important strategies in fighting against climate change due to the presence of soil humus that stabilizes soil organic carbon for a long period of time. Overall, Miombo woodland soils have a high potential for storing substantial SOC stocks. Miombo are composed of different tree species (average of 45 species per biome) with differences in C storage capacity. Thus, strengthening land/forest conservation could lead to build up of SOC stocks that would contribute to global climate change regulation.
Potential of cowpea, pigeonpea and greengram to supply mineral N to maize in rotation on ferralsols in Muheza Tanga- Tanzania
(2008-06) Marandu, A.E.T.; Mrema, J.P.; Nyaki, A. S.; Semu, E.
A rotational field experiment of cowpea, pigeonpea and greengram with maize as married out for two rotational cycles to determine the potential of the legumes to supply N to the subsequent maize. The experiment was carried out on sandy clay Rhodic Ferralsol with bimodal rainfall pattern. The legumes were planted during the short rain season followed by maize during long rains. Soil was sampled from 0 - 20 em layer before maize planting from plots where the legumes were grown and from continuous maize plots. The composite soil samples were sieved through 6 mm screen while fresh. Sub samples equivalent to 250 g each were incubated in 500 ml wide mouth volumetric flasks at 60% field capacity and room temperature for 42 days. Destructive samplings were done at 14 days intervals and analysed for mineral N (NH4+ and N03-). The quantities of mineral N increased with incubation time. Most of the mineral N was mineralised between 0 and 14 days of incubation. Out of the total N mineralized during the entire incubation period, the proportions of the mineral N determined at the 14th day sampling were 64% for the cowpea, 50% for the pigeonpea, 73% for the greengram and 88% for the continuous maize plots. Such high proportions indicate that the subsequent maize would obtain maximum N during these early stages of growth. It was concluded that there is lack of synchrony between the release of mineral N and the maize crops' N demand which lead to the maize N deficiency symptoms and low yields observed in the legume - maize_cropping system.