Browsing by Author "Tumuhairwe, John Baptist"

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    Assessment of plants for phytoremediation of hydrocarbon-contaminated soils in the Sudd Wetland of South Sudan
    (Plant, Soil and Environment, 2019) Alexander Ruley, Jane; Tumuhairwe, John Baptist; Amoding, Alice; Opolot, Emmanuel; Oryem-Origa, Hannington; Basamba, Twaha
    Hydrocarbon contaminants have become a global concern due to their long-term adverse effects on soil ecosystems and human health. Successful implementation of phytoremediation to clean up hydrocarbon contaminants requires the identification of the most effective remediation plant species. Twelve native plant species of the Sudd Wetland in South Sudan were evaluated for their potential application as phytoremediators. The treatments included six total petroleum hydrocarbon (TPH) concentrations of 0, 25, 50, 75, 100 and 125 g/kg soil. The twelve native plant species tested were: Sorghum arundinaceum Desv., Oryza longistaminata A. Chev. & Roehrich, Hyparrhenia rufa Nees, Abelmoschus ficulneus L., Gossypium barbadense L., Nicotiana tabacum L., Sorghum bicolour L. Moench, Eleusine coracana Gaertn., Capsicum frutescens L., Zea mays L., Tithonia diversifolia Hemsl. and Medicago sativa L. Significant differences in phytoremediation rates were observed amongst the treatments with exception of the 125 g/kg soil concentration of hydrocarbon that was lethal to all the plant species. Over 50% TPH reduction in the 75 g/kg soil concentration was observed in contaminated soil phytoremediation in H. rufa, G. barbadense, O. longistaminata, T. diversifolia and S. arundinaceum, making them potential phytoremediators of hydrocarbon-contaminated soil in the Sudd-Wetland of South-Sudan.
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    Bacterial community changes during composting of municipal crop waste using low technology methods as revealed by 16S rRNA1* and Department
    (African Journal of Environmental Science and Technology, 2018) Tumuhairwe, John Baptist; Tenywa, John Stephen
    Bacterial communities are actively involved in composting process but the environment within the compost influences their diversity, abundance and succession. In this study, the authors investigated the bacterial communities in tropical crop waste compost using pyrosequencing. Municipal crop wastes from the tropics (Uganda) were composted under four different low-technology methods. Samples were collected from the early thermophilic, late thermophilic, and mesophilic phases, and from mature compost. Pyrosequencing of the amplified variable V4 region of the 16s rDNA generated over 110 000 sequences. Chao1 and cluster analysis at 3% dissimilarity showed that bacterial community richness declined during the composting process. The community was dominated by a few bacterial taxa during the thermophilic phases. Species evenness increased as compost progressed to maturity despite a decline in the number of taxa over the successional progression. Bacterial community diversity, abundance and succession changed with the composting method. This pattern of diversity may be attributed to competition and selection during the microbial succession. A total of 22 phyla and 513 genera were identified from all the methods in the entire composting process. The most abundant phyla were Proteobacteria, Firmicutes, Bacteriodes and Actinobacteria. Pyrosequencing provided more information on compost bacterial community diversity and abundance than previously used molecular methods. Several novel bacteria existing in tropical crop waste compost remained unclassified.
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    Biological Indicators of Soil Condition on the Kabanyolo Experimental Field, Uganda
    (Agriculture, 2021) Ivanova, Anna; Denisova, Elizaveta; Musinguzi, Patrick; Opolot, Emmanuel; Tumuhairwe, John Baptist; Pozdnyakov, Lev; Manucharova, Natalia; Ilichev, Igor; Stepanov, Aleksey; Krasilnikov, Pavel
    Soil biological activity is an integral characteristic reflecting the state of soil fertility, biodiversity, and the activity of soil processes carried out by soil organisms. In Africa, studies of soil biological properties are few compared to the agrochemical research. In this paper, we present an assessment of multiple biochemical and microbiological properties of soil from an agricultural field located in the African tropical savanna. We determined basal respiration, substrate-induced respiration, C of microbial biomass, the potential activity of denitrification, nitrogen fixation activity, and estimated prokaryotic components in the soil microbial complex by quantitative PCR. Basal respiration of soils ranged from 0.77 0.04 to 1.90 0.23 g C-CO2 g􀀀1 h􀀀1, and substrateinduced respiration ranged from 3.31 0.17 to 7.84 1.04 g C-CO2 g􀀀1 h􀀀1. The C reserves of microbial biomass averaged 403.7 121.6 g C g􀀀1 of soil. The N2O emission from the upper layer on average amounted to 2.79 ng N-N2O g􀀀1 day􀀀1, and the potential denitrification activity reached 745 98 ng N-N2O g􀀀1 h􀀀1. The number of copies of bacterial genes varied from (0.19 0.02) 108 to (3.52 0.8) 108 copies g􀀀1, and of archaea—from (0.10 0.01) 107 to (0.29 0.01) 107 copies g􀀀1 of soil. These results were in good agreement with the studies in other seasonally wet tropical regions: the biological activity was relatively low. The difference between biological indicators of the experimental field and the reference profile were insignificant except for nitrogen loss, which was higher in the ploughed field. Biological indicators strongly varied in space; we explained their heterogeneity by non-uniform management practices in the course of agrochemical field experiments in the past. The use of organic fertilisers may cause the release of climatically active gases due to intensive microbial respiration and denitrification, but the intensity of emission would strongly depend on the cultivation and management method.
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    Comparison Of Four Low-Technology Composting Methods For Market Crop Wastes
    (Waste Management,, 2009) Tumuhairwe, John Baptist; Tenywa, John Stephen; Otabbong, Erasmus; Ledin, Stig
    Four methods for composting, pit-cover (PC), pit-open (PO), above ground-open (AO) and above ground-covered (AC), were compared for their effect in accelerating compost maturity using market crop waste (MCW). The composting process was monitored through determining changes in temperature and pH, with compost maturity indices measured in terms of variations in water-soluble carbon (WSC), ammonium-N () and nitrate-N (), and C/N, , WSC/organic N and WSC/total N (TN). Total organic carbon (TOC), nitrogen (TN), potassium (TK) and phosphorus (TP) were also determined. Temperature rapidly increased from mesophilic to thermophilic and gradually reduced through maturation phases. A similar pattern was recorded for pH, which reached a slightly alkaline level at maturity. Composting significantly (p < 0.05) decreased the concentrations of TOC, TN, TP, TK, and WSC and increased that of . All four low-technology composting methods used in this study produced mature composts within 63 days. Suitable maturity indicators for MCW compost were C/N ratio < 12, WSC < 1%, < 400 mg kg−1, / < 0.2, WSC/TN, WSC/organic-N < 1. On the basis of these indicators, the AC method generally enhanced maturity faster than the AO, PC and PO methods. Pit methods require less investment and are recommended for the smallhold farmers.
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    Sustainable Land Management Paradigm: Harnessing Technologies for Nutrient and Water Management in the Great Lakes Region of Africa
    (Sustainability in Natural Resources Management and Land Planning, 2021) Musinguzi, Patrick; Ebanyat, Peter; Basamba, Twaha Ali; Tumuhairwe, John Baptist; Opolot, Emmanuel; Olupot, Giregon; Tenywa, John Stephen; Mwanjalolo, Jackson Gilbert Majaliwa
    Sustainable Land Management (SLM) is one of the transformative pillars for agricultural development and environment conservation for food, forage, fuel and fiber security. It aims at the tripartite benefits of high yields, environment protection and income security. The success of SLM is a function of adopting appropriate nutrient and water management practices. Several land management practices have been practiced by smallholder farms in the Great Lakes Region of Africa. However, there is still limited understanding of the level of acceptability of the various technologies in mitigating soil water shortage and nutrient depletion. This paper evaluates the SLM concept with focus on assessing sustainability in the use of various soil water and nutrient management technologies and practices. Nutrient management technologies assessed included a range of common inputs and practices in tropical farming systems. Soil water conservation technologies assessed included the physical, biological and agronomic measures. Analysis conducted suggest that few land users can afford to adopt most of the available technologies that define a full package for realization of the pillars of SLM. Integrated use of technologies remains the appropriate approach to responding to the alarming challenge of land degradation. Inclusion of social-cultural and economic factors in the application of SLM technologies of soil, water and nutrients is fundamental for increased adoption. Policies for SLM should target integrated technologies centered on people in order to achieve the ultimate goal of enhanced agricultural productivity, environment conservation and income in the Great Lakes Region of Africa.
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    Transgenic banana plants expressing Xanthomonas wilt resistance genes revealed a stable non-target bacterial colonization structure
    (Scientific Reports, 2015) Nimusiima, Jean; Köberl, Martina; Tumuhairwe, John Baptist; Kubiriba, Jerome; Staver, Charles; Berg, Gabriele
    Africa is among the continents where the battle over genetically modified crops is currently being played out. The impact of GM in Africa could potentially be very positive. In Uganda, researchers have developed transgenic banana lines resistant to banana Xanthomonas wilt. The transgenic lines expressing hrap and pflp can provide a timely solution to the pandemic. However, the impact of the transgenes expression on non-target microorganisms has not yet been investigated. To study this effect, transgenic and control lines were grown under field conditions and their associated microbiome was investigated by 16S rRNA gene profiling combining amplicon sequencing and molecular fingerprinting. Three years after sucker planting, no statistically significant differences between transgenic lines and their non-modified predecessors were detected for their associated bacterial communities. The overall gammaproteobacterial rhizosphere microbiome was highly dominated by Xanthomonadales, while Pseudomonadales and Enterobacteriales were accumulated in the pseudostem. Shannon indices revealed much higher diversity in the rhizosphere than in the pseudostem endosphere. However, the expression of the transgenes did not result in changes in the diversity of Gammaproteobacteria, the closest relatives of the target pathogen. In this field experiment, the expression of the resistance genes appears to have no consequences for non-target rhizobacteria and endophytes.