Browsing by Author "Semu, Ernest"

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Characterization of some typical soils of the miombo woodland ecosystem of Kitonga Forest Reserve, Iringa, Tanzania: physico-chemical properties and classification
(Journal of Agricultural Science and Technology, 2014-03-20) Shelukindo, Hassan Bashiru; Msanya, B. M.; Semu, Ernest; Mwango, Sibaway Bakari; Singh, Bal Ram; Munishi, Pantaleo
Despite the fact that miombo woodland soils have significant implications in global climate change processes, few studies have been done to characterize and classify the soils of the miombo woodland ecosystem of Tanzania. The current study was carried out to map and classify soils of Kitonga Forest Reserve, which is a typical miombo woodland ecosystem, in order to generate relevant information for their use and management. A representative study area of 52 km 2 was selected and mapped at a scale of 1:50,000 on the basis of relief. Ten representative soil profiles were excavated and described using standard methods. Soil samples were taken from genetic soil horizons and analyzed in the laboratory for physico-chemical characteristics using standard methods. Using field and laboratory analytical data, the soils were classified according to the FAO-World Reference Base (FAO-WRB) for Soil Resources system as Cambisols, Leptosols and Fluvisols. In the USDA-NRCS Soil Taxonomy system the soils were classified as Inceptisols and Entisols. Topographical features played an important role in soil formation. The different soil types differed in physico-chemical properties, hence exhibit differences in their potentials, constraints and need specific management strategies. Texture varied from sandy to different loams; pH from 5.1 to 5.9; organic carbon from 0.9 g/kg to 20 g/kg; and CEC from 3 cmol/(+)kg to 24 cmol/(+)kg. Sustainable management of miombo woodlands ecosystem soils requires reduced deforestation and reduced land degradation.
Contents of micronutrients in different vegetables grown in different locations in Tanzania: implications for soil fertility and nutrition potential of the vegetables
(Sokoine University of Agriculture, Tanzania., 2012) Semu, Ernest; Mlaki, J. S.
Samples of twenty two different vegetables were collected from different locations in Tanzania, in three replicates, with the objective of determining their micronutrient contents. The samples were washed, dried, ground, and asked in a muffle fiunace. The ash was dissolved in 10% nitric acid and the extracts made to volume in 25-m1 vohunetric flasks. Copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe) were determined using atomic absorption spec trophotorrktry. The data were subjected to analysis of variance. Results showed that the different types of vegetables contained different quantities of the nutrients. For example, Cu ranged from3.75 ng/kg in egg plant to 8.26 Ingice in sweet potato leaves. Zinc ranged from 13.54 mg/kg in African egg plant to 49.89 mg/kg in cassava leaves (rubber type). Manganese ranged from 15.21 rug/kg in egg plant to 137.19 mg/kg in cassava leaves (cassava) and Fe ranged from 102.08 in African egg plant to 478.11 mg/kg in Chinese cabbage. Within a given type of vegetable, nutrient contents were different across locations of sampling. For example, Cu in amaranthus fiomMorogoro varied from 6.25 rraikg to 7.5 rag/kg, while that fiomMbeya varied from 5 ng/kg to 10.62 mg/kg. Zinc in amaranthus from Mbeya varied from 25.31 rrg/kg to 40 n-alg, while from Vumari- Sank Zn varied from30.31 ap-ika to 39.06 nalg. Manganese in amaranthus fiom Mbeya varied from 89.37 rig/kg to 110 ng/kg, while from Morogoro varied fiom31.25 ng/kg to 35.62 ng/kg. Iron in amaranthus from Vumari-Sane varied from 318.75 mg/kg to 409.37 nig/kg, while from Morogoro Fe varied from 425 mg/kg to 531.25 nvkg. Similar variations were observed in the other types of vegetables. Copper was rated as being low (for pregnant and lactating women). Zinc was generally rated as being low; the rest of the nutrients in the vegetables were deeded adequate for human nutrition.
Copper bioavailability to beans (phaseolus vulgaris) in long-term cu-contaminated soils, uncontaminated soils, and recently cu-spiked soils
(Taylor & Francis, 2015-01-13) Senkondo, Yasin H.; Semu, Ernest; Tack, Filipi M. G.
Copper solubility and its bioavailability to Phaseolus vulgaris in long-term coppercontaminated soils, uncontaminated soils, and copper-spiked soils were studied. The role of plant factors, total copper load in soils, and/or the aging effect on the uptake of copper was explored so as to assess health risks through contamination of the food chain associated with growing the crop on such soils. Contaminated soils and clean soils were collected from coffee-growing fields in Kilimanjaro and Arusha, Tanzania. Two bean seeds were sown per pot, replicated three times, and arranged in a randomized design in a glass house. Copper spiking significantly increased extractable copper, as expected. For all of the treatments except for the Mwanga and Arumeru control soils, the addition of CuSO4 did not significantly increase the humic-acid-bound copper, but it significantly increased the fulvic-acid-bound copper (p = 0.05). Moshi soils had significantly higher concentrations of copper in the bean shoots than was the case with other treatments (p = 0.05). For the respective soil types, there was no significant difference in the concentrations of copper in bean leaves between spiked and unspiked treatments (p =0.05). Bean shoots did not accumulate copper beyond the normal concentrations.
Effect of tillage methods, farmyard manure and potassium rates on some soil chemical properties and nutrient contents in cassava in Kagera, Tanzania
(Journal of Agriculture and Ecology Research International, 2023) Merumba, Mgeta Steven; Semoka, Johnson Mashambo; Semu, Ernest; Msanya, Balthazar Michael; Kibura, Jojianas Kokulamka
A study was conducted in Bukoba, Missenyi and Biharamulo districts, Tanzania for the objective of determining the effect of tillage methods, farmyard manure (FYM) and potassium rates on soil pH and the concentrations of N, P and K in the soils and cassava leaves. The treatments were arranged in the Randomized Complete Block Design (RCBD) using the split-plot design with three replications. Tillage methods (flat tillage, open ridging and tied ridging), were the main plots, and the fertilizer rates [farmyard manure (FYM) alone at 4 MT ha-1 alone or FYM alone at 8 MT ha-1, nitrogen (40 kg N ha-1) + phosphorus (30 kg P ha-1) + potassium at 40, 80 or 120 kg K ha-1 and the combination of FYM alone at 4 MT ha-1 or FYM alone 8 MT ha-1 + potassium at 40, 80 or 120 kg K ha-1] and the control, were the sub-plots. The inherent and post-harvest composite soil samples for determining soil pH and the concentration of N, P and K in each site were collected, processed and analysed. Post-harvest soil samples and cassava leaf samples were collected from the control plots and plots that received the combination of FYM at 8 MT ha-1 and potassium at 40 or 120 kg K ha-1 during the second cropping season. The leaf samples were oven dried at 70oC, grounded to pass through 0.5 mm sieve and analyzed. The results indicate that there was no a significant (P = .05) difference in the soil pH and the concentrations of N, P and K in the soils and cassava leaves among the tillage methods. There was a significant (P < .001) difference in the soil pH and the concentrations of N, P and K in the soils and cassava leaves between the control and the combined use of FYM and potassium rates. However, there was no a significant (P =.05) difference in the concentrations of N, P and K in the soils among the combined use of FYM and potassium rates, but there was a significant (P < .001) difference in the concentrations of N and K in cassava leaves among the combined use of FYM and potassium rates. The combined use of FYM at 8 MT ha-1 and potassium at 40 kg K ha-1, and the combined use of FYM at 8 MT ha-1 and potassium at 120 kg K ha-1 significantly (P < .01) increased the soil pH and the concentration of N and K in the soil. However, the combined use of farmyard manure at 8 MT ha-1 and potassium at 120 kg K ha-1 gave significantly (P < .001) higher concentrations of N and K in cassava leaves than the combined use of farmyard manure at 8 MT ha-1 and potassium at 40 kg K ha-1. Therefore, combined use of farmyard manure at 8 MT ha-1 and potassium at 120 kg K ha-1 is desirable for increasing the concentration of N and K in the soil and in cassava leaves. However, for the resource-poor farmers who cannot afford the high rate of K, the combined use of farmyard manure at 8 MT ha-1 and potassium at 40 kg K ha-1 could be used.
Growth and yield responses of rice, wheat and beans to Zn and Cu fertilizers in soils of Mbeya region, Tanzania
(Sokoine University of Agriculture, 2015) Mhoro, Lyidia; Semu, Ernest; Amuril, Nyambilila; Msanyal, Bathjazar; Munishi, Juvenal 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.
Growth of Streptomyces isolates from four soils in Morogoro, Tanzania, under culture-media pH conditions other than their original environmental pH
(Sokoine University of Agriculture, Tanzania., 2011-12) Semu, Ernest; Akishule, Doris
A study was conducted to assess the ability of Streptomyces isolates to grow under pH conditions other than their original environmental pH. The study involved isolation of Streptomyces from soils in four different locations in Magadu area, Morogoro, Tanzania. The Streptomyces were isolated using the starch-casein agar medium and subsequently grown under different simulated pH conditions, both buffered and unbuffered, in the oat-meal medium. The results of the isolation revealed that the soils had a diversity of Streptomyces isolates, growth of each of which was favoured by particular pH conditions. For the soils with an original pH of 5.0 the growth of two cultures increased and one seemed to show a peak growth when the pH was decreased to 4.5. Others did not show much change in growth. The soils which had a pH of 6.3 had three cultures whose growth was improved when pH wasincreased beyond pH 6.3. Others were almost unchanged. Almost all cultures from soils of pH 7.0 had their growth decreased when pH of the growth medium was increased pH 7.0. The Streptomyces isolates from soils with an original pH of 8.1 showed little change in growth as pH was altered. The colors of the mature colonies that formed when theStreptomyces were grown at various pH levels were cream, white, blue, gray, brown and red, with the cream color being the dominant one. When results of growth of Streptomyces on an unbuffered medium were compared to that on buffered medium, there was generally poor growth of Streptomyces with the latter medium. It was concluded that these Streptomyces which would grow at the buffered pH levels were those that were adapted to those pH conditions. However the unbuffered medium could allow the development of micro-sites with different pH and wider range of pH values conducive to growth of a wider variety of strains.
Participatory land-use planning: integrating expert-oriented and community-based tools for sustainable land management in Kilimanjaro Region
(Department of Soil Science Sokoine, University of Agriculture, Tanzania., 2015) Mahonge, C.P.1; Kashaga, R.A.L.; Kahimba, F. C.; Semu, Ernest; Mkanda, F.X.; Sangeda, A.Z
Tanzania like other countries globally has witnessed a paradigm shift in natural resource planning and management from state-centric to community based approach. The shift was inevitable following the experienced inadequacies of the state capacity in-terms of human and financial resources to manage natural resources in a sustainable way, which in turn exacerbate natural resource degradation. It was consequently envisaged that giving people stake in the planning and management endeavors would help fill the gap. While the manifestation of this shift in the country started since the mid-1990s, little empirical evidence exists on the value of participatory land use planning in ensuring sustainable management of natural resources. This study provides an account on the way participatory land use planning through Sustainable Land Management (SLM) project in Kilimanjaro region has integrated expert-oriented (GIS) and community-based (PRA) tools as a move towards sustainable land management in the region.
Pedological characterization and suitability assessment for cassava production in Bukoba, Missenyi and Biharamulo Districts, Tanzania
(Science Publishing Group, 2020) Merumba, Mgeta Steven; Msanya, Balthazar Michael; Semu, Ernest; Semoka, Johnson Mashambo
A study was conducted in Bukoba, Missenyi and Biharamulo Districts, Tanzania with the objectives of characterizing, classifying and assessing the suitability of the study area for cassava production. A reconnaissance field survey using transect walks and auger observations was done in the study sites, which were geo-referenced in terms of international coordinates using Global Positioning System. Soil profiles representative of the study sites were excavated and named as MARU-P1, MISSE-P1 and BIHA-P1 for Bukoba, Missenyi and Biharamulo Districts, respectively. Soil profile description and data on the morphological features of the representative soils were collected according to the FAO Guidelines for Soil Description. Disturbed and undisturbed soil samples were collected from genetic soil horizons, processed and analyzed in a soil laboratory. Data on site characteristics, climate, soil morphological features and soil physical and chemical properties were used to classify the soils to the family level of the USDA Soil Taxonomy and to tier-2 of the FAO World Reference Base for Soil Resources. Soil suitability assessment of the experimental sites was done using a simple limitation method based on the FAO Framework for Land Evaluation. The results reveal that Pedons MARU-P1 and BIHA-P1 have similar morphological properties, which are different from pedon MISSE-P1. However, the studied pedons differ in their physical and chemical properties, implying differences in their use and management. The climate of the study sites is semi-humid with Udic soil moisture regime, which is generally favourable for crop production. According to the USDA Soil Taxonomy, pedons MARU- P1 and BIHA-P1 were classified as “Typic Kandiudults”. In addition, according to FAO World Reference Base for Soil Resources, pedons MARU-P1 and BIHA-P1 were classified as “Haplic Ferralic Acrisols” and “Chromic Ferralic Acrisols”, respectively. Pedon MISSE-P1 was classified as “Typic Endoaquolls” according to USDA Soil Taxonomy and as “Fluvic Gleyic Phaeozems” according to FAO World Reference Base for Soil Resources. Pedons MISSE-P1 and BIHA-P1 were both evaluated as marginally suitable while MARU-P1 pedon was evaluated as moderately suitable for cassava production due to soil fertility constraints. We recommended specific soil fertility management strategies in each studied site for optimum cassava yields.
Potential of soil fertility management to improve essential mineral nutrient concentrations in vegetables in Dodoma and Kilombero, Tanzania
(Scientific Research Publishing Inc., 2017) Amuri, Nyambilila A; Mhoro, Lydia; Mwasyika, Tumaini; Semu, Ernest
Collective efforts to fight mineral nutrient malnutrition in humans require consideration of soil fertility management practices (SFMP) in vegetable pro duction. This study aimed at establishing the relationship between SFMP and vegetable nutrient concentration for human health in farming systems of Tanzania. Soil and vegetable samples collected from vegetable growing areas in Kilombero and Dodoma were analyzed for chemical properties and mineral nutrient concentration. Descriptive statistics, analysis of variance and correla tion analysis were employed. The results showed that soil pH in Kilombero ranged from 6.04 to 6.8 and in Dodoma ranged from 6.23 to 8.58. The organic C was low, ranged from 0.10% to 1.87%. All soils studied had sufficient Zn (0.45 to 29.3 mg/kg), Cu (0.71 to 3.23 mg/kg), Fe (3.70 to 171.7 mg/kg) and Mn (2.84 to 41.38 mg/kg). Zinc concentration in all vegetables ranged from 12.57 to 134.54 mg/kg, 14% of vegetables had low Zn (<20 mg/kg) for human health. The Cu concentration in vegetables ranged from 0.07 to 52.37 mg/kg, and vegetables from Kilombero had very low Cu (<0.10 mg/kg) for plant and human nutrition. Vegetable Fe and Mn concentration ranged from 152.95 to 1780 mg/kg and 35.10 to 321.82 mg/kg, respectively. The SFMP used did not affect mineral micronutrients concentration in vegetables, but affected soil Zn, Cu, Fe and Mn concentrations. Soil pH, Zn, and CEC correlated with vegeta ble Cu, K, Mg, Zn, P and Fe concentrations, and differed among soils. There fore, soil properties differed with SFMP, and both determined mineral con centrations in vegetables for human health.
Predictor variables for soil organic carbon contents in the Miombo woodlands ecosystem of Kitonga Forest Reserve, Tanzania
(International Scholars Journals, 2014-05-20) Shelukindo, Hassan Bashiru; Semu, Ernest; Msanya, B. M.; Singh, Bal Ram; Munishi, Pantaleo K.T
Few studies have established the variables which adequately predict SOC storage in the Miombo woodlands. Multiple regression analysis was used to establish the variables which could predict SOC contents in dominant soils of the Miombo woodlands of Kitonga Forest Reserve, Tanzania. Thirty soil mini- pits located at different elevations across a topographical gradient were selected, geo-referenced, excavated and samples from the natural horizons were collected for physico-chemical analysis. A total of 85 samples were collected, each representing a natural soil horizon. The results indicated that total nitrogen (TN), (P< 0.001, R 2 = 0.97) and TN in combination with calcium (Ca) (P< 0.001, R 2 = 0.99) were important predictor variables of SOC contents. The combination of cation exchange capacity, Zinc, Copper, clay and iron together with TN and Ca predicted well the SOC contents (P< 0.001, R 2 = 0.999). Considering time and cost implications for field and laboratory analysis in predicting SOC stocks, the combination of TN and Ca that predicted the SOC contents by 99% provided equally strong prediction when compared to the combination of all the variables. Thus, proper land management strategies which enhance conservation of TN and Ca in concert would provide adequate prediction of SOC contents in soils.
Profitability of using different rates of farmyard manure and potassium fertilizer for cassava production in Bukoba, Missenyi and Biharamulo districts, Tanzania
(ResearchGate, 2022-08-10) Merumba, Mgeta Steven; Semu, Ernest; Semoka, Johnson Mashambo; Msanya, Balthazar Michael; Kibura, Jojianas Kokulamka; Blandes, Joyce Siima
The resolution of using or not using a particular technology in crop production is governed by the profitability of that technology being used. A study was conducted in Bukoba, Missenyi and Biharamulo districts in the Kagera region during the 2018/19 and 2019/20 cropping seasons to determine the economic benefit of using different rates of farmyard manure (FYM) and potassium (K) fertilizer in cassava production. One village potential for cassava production was selected in each district for establishment of cassava trials. Three tillage methods [flat tillage, tied ridging and -1 -1 open ridging] and eleven fertilizer rates [FYM at 4 or 8 MT ha , N40P30 + K at 40, 80 or 120 kg ha , FYM at 4 or 8 MT ha-1 + K at 40, 80 or 120 kg ha-1] and the control, were arranged in a Randomized Complete Block Design (RCBD) with three replications using a split-plot design. Tillage methods were the main plots and fertilizer rates were the subplots. Cassava yields (MT ha-1) were collected at harvesting (12 months after planting). Partial budget analysis was carried out to estimate the gross values using the adjusted yields at market price for cassava and fertilizers. Costs and benefits -1 -1 were calculated on a hectare basis, in Tanzania Shillings (TShs) ha , and converted to USD ha based on the prevailing exchange rate of 1 USD, equivalent to 2 300 TShs. All variable costs were summed up to total variable cost (TVC). The net benefits (NB) [gross benefit (GB) - TVC] ha-1 of the tested treatments were calculated and used to assess the profitability of each treatment. Moreover, the benefit-cost ratios (BCR) [net benefit ÷ TVC] of the tested treatments were compared to the acceptable value of greater than 2 for the technology to be adopted by farmers. The results indicated that in both cropping seasons, and in all studied sites, all the tested fertilizer types and rates gave acceptable BCR of greater than 2, implying that all the fertilizer types and rates could be used for cassava production in the study area. The results on net benefit indicated that the combined use of FYM at 8 MT ha-1 and potassium fertilizer at 80 kg K ha-1 gave higher net benefit (3 020 500 – 9 168 000 TShs ha-1 (1 313.3 – 3 986.1 USD ha-1) than the other fertilizer types and rates (1 915 000 – 9 024 500 (832.6 – 3 923.7 USD ha-1) and is therefore, desirable for increasing cassava root yield and net benefit. However, for the resource-poor farmers, the combined use of farmyard manure at 8 MT ha-1 and potassium fertilizer at 40 kg K ha-1 can still be adopted because, for some reason, not all the famers can afford the best treatment.
Proton consumption capacity, ash alkalinity and chemical characterization of travertine from different sources in Rwanda
(Department of Soil Science Sokoine, University of Agriculture, Tanzania., 2014-08-06) Sirikare, N.S.; Naramabuye, F.X; Marwa, E.; Semu, Ernest
Soil acidification is among the major factors limiting the sustainability of agricultural production systems throughout the world and more specifically in Rwanda. Travertine samples collected from different deposits in Rwanda were examined for their chemical compositions. Calcium oxide (CaO) content, ash alkalinity and protons consumption capacity were determined as potential indicators to predict the efficiency of travertine. The results found revealed that the studied travertine deposits (Rwaza, Mashyuza, Gishyita and Mpenge) in Rwanda had 35 to 71.1 wt% CaO. Magnesium Oxide (MgO) ranged between 3.1 and 12.7 wt%. Travertine had micronutrients CI, Zn, Cu, Mo and Co that can offset deficiency encountered in highly weathered Rwandan acidic soils. In addition, these travertine deposits had higher proton consumption capacity and ash alkalinity as compared to other liming materials. The study revealed positive linear correlations among all the investigated indicators, which could serve as a model for predicting proton consumption capacity and ash alkalinity of any liming material when its pH and CaO content are known. It was recommended that travertine from Rwanda could be used for soil acidity amelioration and a potential zource of micronutrients for agricultural production.
Soil fertility status in Bukoba, Missenyi and Biharamulo Districts in Kagera Region, Tanzania
(Science Publishing Group, 2020) Merumba, Mgeta Steven; Semu, Ernest; Semoka, Johnson Mashambo; Msanya, Balthazar Michael
The study was conducted in three Districts of Kagera Region, Tanzania to assess the inherent soil fertility status of farmers' fields. Thirty-three fields, located three to five km apart, were selected and soil samples (0 – 20 cm depth) were taken, mixed thoroughly, air-dried, ground, sieved through 2 mm sieve, and analyzed in the soil laboratory based on standard laboratory analytical procedures. Correlation analyses among soil chemical properties were performed using IBM SPSS Statistic 20 and the mean values were calculated using Excel spreadsheet statistical package. Soil fertility index (SFI) and limiting nutrients were used to assess the fertility status of the fields. The results indicated that soil textures ranged from sandy clay loam to sandy clay, clay loam, clay to sandy. Soil pH ranged from strongly acid (5.1) to slightly acid (6.1) while EC levels were very low (0.03 - 0.17 dS m-1). Total TN ranged from very low to medium (0.04 - 0.41%), extractable P ranged from low to high (0.44 - 86.44 mg kg-1) and Exchangeable K ranged from very low to medium (0.08 - 0.98 cmol(+) kg-1). Exchangeable S ranged from low to medium (2.27 - 12.14 mg kg-1) while CEC ranged from very low to medium (5.20 - 23.00 cmol(+) kg-1), extractable Zn ranged from medium to high (0.85 - 18.41 mg kg-1), Cu from medium to high (0.47 - 2.81 mg kg-1), and Mn and Fe were medium (2.24 - 70.34 mg kg-1) and high (37.50 - 473.21 mg kg-1), respectively. The results also indicated both positive (r=+ve) and negative (r=-ve) and both significantly (p≤0.05) and highly significantly (p≤0.01) correlations among the soil chemical properties in each districts. Based on SFI, the soil fertility status of the studied fields ranged from poor fertility to good fertility. The results on the limiting nutrients across the studied fields indicated that N and K were the most limiting nutrients (67%) followed by P (52%), S (32%), Mg and OC (18%) and the least was Ca (15%). The results also indicated that N and P were the most limiting nutrients in Bukoba District while N and S were the most limiting nutrients in Missenyi District and N, P and K were the most limiting nutrients in Biharamulo District. Therefore, specific soil fertility management practices are recommended based on limiting nutrients in those fields having inadequate levels of plant nutrients together with training of farmers on proper use of the appropriate soil fertility management practices.
Soil organic carbon stocks in the dominant soils of the Miombo woodland ecosystem of Kitonga Forest Reserve, Iringa, Tanzania
(International Journal of Agricultural Policy and Research, 2014-03-06) Shelukindo, Hassan Bashiru; Semu, Ernest; Msanya, B. M.; Singh, Bal Ram; Munishi, Pantaleo K.T
Few studies have determined the soil organic carbon (SOC) stocks in the Miombo woodlands ecosystem in Tanzania. Standard field and laboratory procedures were used to evaluate SOC storage in the Miombo woodlands ecosystem of Kitonga Forest Reserve Iringa, Tanzania. A study area of 52 km 2 was selected and ten soil profiles were studied. Representative sampling points were geo-referenced and soil samples collected from natural horizons to the depth of 60 cm. Results show that the total soil organic carbon stocks in soil profiles varied from 19.4 to 28.9 Mg C ha -1 in leptosols; from 45.6 to 80.1 Mg C ha -1 in fluvisols; and from 33.9 to 134.6 Mg C ha -1 in cambisols. The SOC increased significantly (p< 0.05) with increasing elevation, horizon thickness and % clay, but it decreased significantly (p< 0.05) with increasing slope gradient and increasing % sand. The areal distribution of the soil types was 61%, for cambisols, 19% for leptosols, 11% for fluvisols and 9% for natural forest which was not surveyed because of inaccessibility. Proper management of Miombo woodlands would increase the SOC storage and contribute to climate change regulation.
Vertical distribution of copper in copper-contaminated coffee fields in Kilimanjaro, Tanzania
(Taylor & Francis, 2015) Senkondo, Yasin H.; Semu, Ernest; Tack, Filipi M. G.
Soils in coffee farms may be contaminated with copper (Cu) due to intensive and long-term use of Cu-based fungicides. This legacy of Cu contamination may pose risks for contaminating lower soil layers and underground water, or contamination of food crops cultivated on these soils. High concentrations of Cu, strongly exceeding international standard levels, were found within the top 30 cm of affected soils. There was only a limited mobility of Cu below 30 cm layers, suggesting a low risk of contaminating lower soil layers. The Cu mobility in fallow soils was more limited than in tilled soils. There was a positive correlation between silt content and the concentrations of Cu. Potentially mobile Cu fractions, which decreased with soil depth, were greater in contaminated soils than in uncontaminated soils and were greater in top layers than in lower layers, implicating greater Cu availability and consequently higher toxicity risks.