Browsing by Author "Opolot, Emmanuel"
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Item Application of Remote Sensing and Geographical Information Systems in Flood Management: A Review(Research journal of applied sciences engineering and technology, 2013) Opolot, EmmanuelFloods are one of the most widely distributed hazards around the world and their management is an important issue of concern among all the stakeholders. The aim of this review is to synthesize the state of art literature in the application of Geographical Information Systems (GIS) and Remote Sensing (RS) techniques in all the flood management stages (pre-flood, during flood and post-flood stages). Flood types and common concepts in flood management are precisely explained. Case studies of flood management using GIS and RS are summarized. Current challenges in using GIS and RS techniques for flood management are also given. One lesson we learn from this review is that flood management is very diverse and it requires multidisciplinary involvement. It can also be deduced that RS techniques offer cheaper and faster options of accessing spatial data about the flood event even in the physically inaccessible areas. GIS techniques on the other hand facilitate hydrological models in data collection, analysis, querying and presentation of information in a more simplified format. The present review is expected to contribute to an improved understanding of the potential applications of RS and GIS techniques in flood management, especially among scientists in the developing countries where the use of these techniques particularly in flood management has generally been limited.Item 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, TwahaHydrocarbon 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.Item 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, PavelSoil 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 g1 h1, and substrateinduced respiration ranged from 3.31 0.17 to 7.84 1.04 g C-CO2 g1 h1. The C reserves of microbial biomass averaged 403.7 121.6 g C g1 of soil. The N2O emission from the upper layer on average amounted to 2.79 ng N-N2O g1 day1, and the potential denitrification activity reached 745 98 ng N-N2O g1 h1. The number of copies of bacterial genes varied from (0.19 0.02) 108 to (3.52 0.8) 108 copies g1, and of archaea—from (0.10 0.01) 107 to (0.29 0.01) 107 copies g1 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.Item Decomposition and nutrient release patterns of municipal solid waste compost in two agro‑ecological zones of Uganda(Agriculture & Food Security, 2022) Kiiza Kabasiita, Juliet; Opolot, Emmanuel; Sande, Eric; Malinga, Geoffrey MaxwellDeteriorating soil fertility is a major constraint to agricultural production and food security among smallholder farmers in Uganda and throughout sub-Saharan Africa, where the majority of the population relies on subsistence farming for its livelihoods. Unfortunately, inorganic fertiliser used as a significant soil nutrient replenishment is unsustainable, causing adverse environmental effects, including soil acidification and pollution of water bodies. Therefore, finding alternative, more sustainable, low-cost nutrient management systems is vital. This study assessed the decomposition and nutrient release patterns of municipal solid waste compost (MSWC) in a 36 weeks litter bag experiment under field conditions in two agro-ecological zones (AEZs) of Uganda. Results: We found a higher rate of decomposition in the South-western Grass Farmlands (SGF) agro-ecological zone (0.041 week− 1, with 20% of initial compost mass remaining after 36 weeks of decay) compared to Southern and Eastern Lake Kyoga Basin (SEKB) (0.043 week− 1, 32% of initial litter mass remaining). The half-life values were 16 and 17 weeks for SGF and SEKB AEZs, respectively. The nutrient release rates differed between the two study sites. The macronutrient release pattern in both sites followed the order K > P > N. The secondary macronutrients release followed the order Ca > Mg in the SGF, while in SEKB, the order was reversed. The micronutrients followed the order Cu > Mn > Fe > Zn and Cu > Mn > Zn > Fe in SGF and SEKB AEZs, respectively. The MSWC mass loss during decomposition was negatively correlated with rainfall in both AEZs and with temperature in SGF AEZ, while it was positively correlated with temperature in SEKB AEZ. However, the relationship with nutrient release rates was inconsistent in both AEZs. Conclusions: Our results showed consistent release of nutrients in all AEZs throughout the study period, which coincides with the two cropping seasons in Uganda, suggesting that smallholder farmers can use MSWC as a soil amendment to address soil fertility decline and improve crop productivity. However, because most nutrients were released almost right away in both AEZs, planting should be done at the beginning of high rainfall months when soil moisture is high to synchronise nutrient release from MSWC with crop demand and maximise nutrient uptake by crops while minimising losses to the environment. Furthermore, the inconsistent relationships between the climatic variables and nutrient release suggest that other factors, such as site-specific microbial composition, influenced MSWC nutrient release. Therefore, long-term research is needed to examine other factors affecting nutrient release in these AEZs.Item Evaluating in Situ Water and Soil Conservation Practices with a Fully Coupled, Surface/Subsurface Process‐Based Hydrological Model in Tigray, Ethiopia(Land Degradation & Development, 2016) Opolot, Emmanuel; Araya, Tesfay; Nyssen, Jan; Al-Barri, Bashar; Verbist, Koen; Cornelis, Wim M.In situ water and soil conservation (WSC) practices are a promising intervention to improve rainwater management particularly in the semiarid to dry sub-humid tropics. This study applies a fully coupled surface–subsurface process-based model (HydroGeoSphere) to simulate in detail rainwater partitioning as affected by two in situ WSC practices [terwah+ (TER+) and derdero+ (DER+)] currently under study on Vertisols in Tigray, Ethiopia and to evaluate the treatments in terms of rainwater partitioning. In the TER+ practice, contour furrows of 0·2m wide and 0·1m deep are created at 1·5m intervals between permanent broad beds, whereas in DER+, permanent raised beds 0·6m wide with furrows 0·2m wide and 0·1m deep are created, to minimize runoff and water logging. The model accurately reproduced measured surface runoff (e.g. in DER+: Nash–Sutcliffe model efficiency E = 0·6 for calibration and 0·7 for verification) and soil moisture content (DER+: E = 0·6 for calibration and 0·8 for verification). Runoff depth was lowest under DER+ (50 mm) followed by TER+ (67 mm) and significantly higher in conventional tillage (CT) (160 mm). Simulated transpiration, evaporation and drainage out of the root zone were all higher under DER+ and TER+ compared with CT. The effects of DER+ and TER+ practices on rainwater partitioning were more pronounced in wet years than in dry years. The model proved to be a promising and versatile tool to assess the impact of WSC practices on rainwater partitioning at the field scale.Item Factors influencing utilization of municipal solid waste compost among urban farmers in western Uganda(CABI Agriculture and Bioscience, 2021) Kiiza Kabasiita, Juliet; Malinga, Geoffrey Maxwell; Odongo, Julius C. W.; Opolot, EmmanuelEffective management of solid waste is one of the most serious environmental problems confronting urban governments in developing countries due to insufficient financial resources and institutional capacity to provide basic solid waste management infrastructure, impoverished urban populations, low rates and coverage of collection, and rising food consumption rates. Composting has been touted as the most economical solution for reducing organic fraction of urban waste volumes while releasing vital nutrients for the soils. However, there is a paucity of information on utilization and associated factors of urban wastes in Uganda. This study aims to assess the level of utilization of Municipal Solid Waste (MSW) compost produced from Clean Development Mechanism (CDM) plants and associated factors among farmers in Fort Portal and Mbarara Municipalities, western Uganda. Methods: Data was collected using a cross-sectional survey from 359 and 361 randomly selected farmers in Mbarara and Fort Portal, respectively. A semi-structured questionnaire was employed to collect quantitative data and analyzed statistically using SPSS and STATA statistical programs. Probit model was used to determine factors that influence farmers’ decisions to utilize MSW compost as a soil conditioner. Results: The findings revealed a very low level of utilization in both municipalities, 1.7% in Fort Portal and 2.2% in Mbarara. The results indicated that annual farm income, access to other soil conditioners, experience with the use of fertilizers, membership to a farmers’ group and the cost of MSW compost significantly influenced farmers’ decision to use MSW compost. Conclusions: The findings call for government investment in policies aimed at increasing the level of utilization of the MSW compost by improving accessibility to soil conditioners, creating opportunities for maximizing household incomes, farmer-to-farmer experience sharing, dissemination of information through extension programmes and other innovative communication approaches, operationalization of farmers’ groups and introduction of subsidy schemes on the price of compost through operational tax waivers in urban areas of Uganda. Finally, to guarantee quality and to improve the adoption of compost generated at the CDM plants, there is a need for research to assess the quality of MSW compost, undertake a supply chain analysis and cost–benefit study and set a price commensurate with the quality, and develop guidelines and rates of application of the MSW compost.Item Fully Coupled Surface–Subsurface Hydrological Modeling to Optimize Ancient Water Harvesting Techniques(Handbook ofWater Harvesting and Conservation: Case Studies and Application Examples, 2021) Cornelis, Wim M.; Verbist, Koen; Araya, Tesfay; Opolot, Emmanuel; Wildemeersch, Jasmien C.J.; Al-Barri, BasharWorldwide, but particularly in drylands, water scarcity has become a major limitation to crop production and to delivering ecosystemservices in general. Likewise, in many regions rainfall is becoming more erratic, with later and shorter rainy seasons, more and longer dry spells, and fewer rainy days (Sillmann et al. 2013), even in cases when total rainfall is increasing (Wu et al. 2013; Greve et al. 2014). This might be linked to anthropogenic climate change (Rockström and Falkenmark 2015). It results in a higher frequency of particularly agricultural droughts – shortage of available water for plant growth – which generally occur more often than meteorological droughts, i.e. shortage of precipitation (Wani et al. 2009). In order to improve food and water security, water harvesting in its broadest sense should be an entry-point activity to enhance crop production through sustainable/ ecological intensification. On a larger scale it contributes to regreening of the landscape, through crops, grasses, shrubs, or trees, hence rendering ecosystem services for society (Stroosnijder 2009). In a broad sense,water harvesting refers to retaining rainwater by in situ and ex situ practices (Dile et al. 2013; Cornelis 2014). In situ practices capture and store water where it falls, whereas ex situ practices collect water from a larger area and convey it to fields for immediate use or to storage systems for later use. Various examples are given elsewhere within this book.Item Iodine Agronomic Biofortification of Cabbage (Brassica oleracea var. capitata) and Cowpea (Vigna unguiculata L.) Is Effective under Farmer Field Conditions(Agronomy, 2019) Ojok, Joe; Omara, Peter; Opolot, Emmanuel; Odongo, Walter; Olum, Solomon; Gijs, Du Laing; Gellynck, Xavier; Steur, Hans De; Ongeng, DuncanIodine (I) is an essential micronutrient, which plays a critical role in human metabolism. However, its concentration is known to be low in most soils, making it deficient in crops. With most I agronomic biofortification studies conducted under controlled environments, limited information currently exists on this approach of enriching I deficient crops under farmer field conditions. Two-year field experiments were conducted in 2017 and 2018 to examine efficacy of cowpea and cabbage in the uptake of foliar applied potassium iodide (KI) and potassium iodate (KIO3), each with 0, 5, 10, and 15 kg I ha−1 under farmer field conditions. Results indicate that KI was 34% more efficient than KIO3. Iodine concentration increased with application rate. In cabbage, the lowest I concentration (8.2 mg kg−1) was registered at 5 kg I ha−1 with KIO3 while the highest was 109.1 mg kg−1 at 15 kg I ha−1 with KI. Cowpea registered the lowest I concentration of 531.5 mg kg−1 at 5 kg I ha−1 with KIO3 while the highest (5854.2 mg kg−1) was registered at 15 kg I ha−1 with KI. Therefore, cowpea and cabbage can be effectively biofortified through foliar application of both KI and KIO3 under farmer field conditions.Item Novel Climate Smart Water and Nutrient Conservation Technologies for Optimizing Productivity of Marginal Coarse-Textured Soils(Cham: Springer International Publishing, 2021) Olupot, Giregon; Smucker, A. J. M.; Kalyango, S.; Opolot, Emmanuel; Orum, Boniface; Musinguzi, Patrick,; Twaha, A. B.; Singh, B. R.Water and nutrients are the two most limiting factors to productivity especially under rain-fed agriculture (RFA) in moist, semi-arid and arid regions. The dramatic doubling in yields and production from the 1960s to the 1990s, were through rapid expansion into irrigated prime land (FAO 1986; Higgins et al. 1988; Fischer et al. 2010; FAO 2011a). The prospects of further expanding agriculture into uncultivated lands and, into lakes, rivers, swamps and marshes (as alternative sources of water) are bleak. Withdrawal and consumption of these resources have already surpassed the Earth’s supply and regeneration capacity (Fischer et al. 2010). Higgins et al. (1988) estimated water requirements for food intake (in cereal equivalents) of 300 kg cap−1 yr−1 at 600 to 3,000 m3 cap−1 yr−1 (1 m3 = 1,000 L). Out of the Earth’s renewable water resources totaling 42,000 km3 annually, 3,900 km−3 is already being abstracted from rivers and aquifers distributed as 70% (2,730 km3) irrigation, 19% (741 km3) industrial and 11% (429 km3) municipal uses (Fischer et al. 2010; FAO 2011a). Water withdrawals exceeding 20% exert substantial pressure on renewable freshwater resources and those exceeding 40% are considered critical (Fischer et al. 2010; FAO 2011a). Withdrawals in the Middle East, North Africa and Central Asia already exceed critical thresholds with demand outstripping supply, posing serious threats to ecological functions of the water resources (FAO 2011a; Fischer et al. 2010). China, India, USA, Russia, Germany and Pakistan dominate irrigated area globally (Higgins et al. 1988; Fischer et al. 2010; FAO 2011a).Item Quality and Fertility Assessments of Municipal Solid Waste Compost Produced from Cleaner Development Mechanism Compost Projects: A Case Study from Uganda(Agriculture, 2022) Kiiza Kabasiita, Juliet; Opolot, Emmanuel; Malinga, Geoffrey MaxwellDespite the fact that compost projects under the Cleaner Development Mechanism (CDM) have been implemented in Sub-Saharan Africa in recent years, there is a paucity of information on the quality of compost produced from the compost plants. This study fills this gap by evaluating the properties of MSWC produced from 12 CDM plants in Uganda based on quality and fertilizing indices. pH, Pb N, K, P, Mn, Cd, Ca, Mg, Cu, Fe, Cr, Zn, OC, and CN levels differed significantly between locations. MSWC’s Fertility Indices (FI) ranged from 1.9 to 2.9, with Mbarara having the highest (2.9) and Soroti having the lowest (1.9). Fort Portal, Mbarara, Kasese, and Masindi have Clean Indices (CI) ranging from 3.8 to 4.9. According to the results of the fertility and Clean Indices analysis, all MSW composts generated at CDM facilities have low fertilizing capacity and poor quality and are classified as Class RU-1, which does not meet international and national compost criteria. As a result, these composts cannot be utilized as fertilizers and can only be used as soil conditioners under certain conditions. Windrow composting has been proven to be a viable method for lowering huge amounts of organic municipal solid waste in urban areas, and it can be scaled up to other parts of the world according to this study. Authorities must, however, engage urban citizens in waste separation at the source and MSWC enrichment with organic sources. This will aid in improving its quality and fertilizing capacity, as well as in ensuring that the MSWC produced is uniform and suited for use in agriculture and the market.Item Sensitivity of mineral dissolution rates to physical weathering : A modeling approach(European Geosciences Union (EGU), 2015) Opolot, Emmanuel; Finke, PeterThere is continued interest on accurate estimation of natural weathering rates owing to their importance in soil formation, nutrient cycling, estimation of acidification in soils, rivers and lakes, and in understanding the role of silicate weathering in carbon sequestration. At the same time a challenge does exist to reconcile discrepancies between laboratory-determined weathering rates and natural weathering rates. Studies have consistently reported laboratory rates to be in orders of magnitude faster than the natural weathering rates (White, 2009). These discrepancies have mainly been attributed to (i) changes in fluid composition (ii) changes in primary mineral surfaces (reactive sites) and (iii) the formation of secondary phases; that could slow natural weathering rates. It is indeed difficult to measure the interactive effect of the intrinsic factors (e.g. mineral composition, surface area) and extrinsic factors (e.g. solution composition, climate, bioturbation) occurring at the natural setting, in the laboratory experiments. A modeling approach could be useful in this case. A number of geochemical models (e.g. PHREEQC, EQ3/EQ6) already exist and are capable of estimating mineral dissolution / precipitation rates as a function of time and mineral mass. However most of these approaches assume a constant surface area in a given volume of water (White, 2009). This assumption may become invalid especially at long time scales. One of the widely used weathering models is the PROFILE model (Sverdrup and Warfvinge, 1993). The PROFILE model takes into account the mineral composition, solution composition and surface area in determining dissolution / precipitation rates. However there is less coupling with other processes (e.g. physical weathering, clay migration, bioturbation) which could directly or indirectly influence dissolution / precipitation rates.We propose in this study a coupling between chemical weathering mechanism (defined as a function of reactive area, solution composition, temperature, mineral composition) and the physical weathering module in the SoilGen model which calculates the evolution of particle size (used for surface area calculation) as influenced by temperature gradients. The solution composition in the SoilGen model is also influenced by other processes such as atmospheric inputs, organic matter decomposition, cation exchange, secondary mineral formation and leaching. We then apply this coupled mechanism on a case study involving 3 loess soil profiles to analyze the sensitivity of mineral weathering rates to physical weathering. Initial results show some sensitivity but not that dramatic. The less sensitivity was attributed to dominance of resistant primary minerals (> 70% quartz). Scenarios with different sets of mineralogy will be tested and sensitivity results in terms of silicate mineral dissolution rates and CO2-consumption will be presented in the conference.Item 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 MajaliwaSustainable 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.