Browsing by Author "Musinguzi, Patrick"
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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 Climate Change Effect on Water Use Efficiency under Selected Soil and Water Conservation Practices in the Ruzizi Catchment, Eastern D.R. Congo(Land, 2022) Bagula, Espoir M.; Majaliwa, Jackson Gilbert M.; Mushagalusa, Gustave N.; Basamba, Twaha A.; Tumuhairwe, John-Baptist; Mondo, Jean-Gomez M.; Musinguzi, Patrick; Mwimangire, Cephas B.; Chuma, Géant B.; Egeru, Anthony; Tenywa, Moses M.Concerns have been raised on the effectiveness and sustainability of Soil and Water Conservation (SWC) practices as adaptation options to climate change and high intra– and inter–annual rainfall variabilities in eastern Democratic Republic of Congo (DRC). This study was conducted in the Ruzizi Plain, a dryland area, to assess the performance of maize (Zea mays L.) under two Representative Concentration Pathways (RCP 4.5 and 8.5) and two SWC practices (tied ridges and conventional tillage). The AgMIP’s Regional Integrated Assessment (RIA) approach was used to simulateWater Use Efficiency (WUE) under the Cropping System Model–Crop Environment Resource Synthesis (CSM–CERES–Maize) of the Decision Support System for Agro–technology Transfer (DSSAT). The model was calibrated using experimental data from nine cropping seasons (2011–2018) and 100 farms. The model sensitivity was assessed as a function of temperature, water, and SWC practices for the same environments. Initial conditions of crop management practices were used as input data for CSM–CERES–Maize. Current climate data were extracted from AgMERRA datasets corrected with local data for the period of 1980 to 2021. Future climate projections (2022–2099) were obtained after downscaling the data from the 29 General Circulation Models (GCMS) of Coupled Model Intercomparison Project 5 (CMIP5) and subsetted to five GCMs based on climate regimes. GCMS results were a strong indicator that climate change in this DRC dryland will result in an increase in average annual temperatures for both RCP 4.5 and 8.5, with the highest increase (3.05 C) under hot/dry conditions for RCP8.5 and the lowest (1.04 C) under cool/dry conditions for RCP 4.5. All the models selected for five climate regimes for 2022–2099 showed no change in the rainfall trends for RCP 4.5 (p > 0.05). The models projected yield declines of 5–25%, with less yield losses under tied ridges as an adaptation practice. The use of efficient SWC practices could therefore be a promising strategy in reducing potential losses from climate change in drylands of eastern DRC.Item Critical soil organic carbon range for optimal crop response to mineral fertiliser nitrogen on a ferralsol(Experimental Agriculture, 2016) Musinguzi, Patrick; Ebanyat, Peter; Tenywa, John Stephen; Basamba, Twaha Ali; Tenywa, Moses Makooma; Mubiru, Drake N.Soil Organic Carbon (SOC) is a major indicator of soil fertility in the tropics and underlies variability in crop response to mineral fertilizers. Critical SOC concentrations that interact positively with N fertilizer for optimal crop yield are less understood. A study was conducted on a Ferralsol in sub-humid Uganda to explore the critical range of SOC concentrations and associated fractions for optimal maize (Zea mays L.) yield response to applied mineral N fertiliser. Maize grain yield response to N rates applied at 0, 25, 50 and 100 kg N ha−1 in 30 fields of low fertility (SOC < 1.2%), medium fertility (SOC = 1.2–1.7%) and high fertility (SOC > 1.7%) was assessed. Soil was physically fractionated into sand-sized (63–2000 µm), silt-sized (2–63 µm) and clay-sized (<2 µm) particles and SOC content determined. Low fertility fields (<1.2% SOC) resulted in the lowest response to N application. Fields with >1.2% SOC registered the highest agronomic efficiency (AE) and grain yield. Non-linear regression models predicted critical SOC for optimal yields to be 2.204% at the 50 kg N ha−1 rate. Overall, models predicted 1.9–2.2% SOC as the critical concentration range for high yields. The critical range of SOC concentrations corresponded to 3.5–5.0 g kg−1 sand-sized C and 9–11 g kg−1 for clay-sized C.Item High viral suppression and low attrition in healthy HIV-infected patients initiated on ART with CD4 above 500 cells/μL in a program setting in Uganda(Afri Health Sci, 2020) Byonanebye, Dathan M.; Semitala, Fred C.; Katende, Jackson; Bakenga, Alex; Arinaitwe, Irene; Kyambadde, Peter; Musinguzi, Patrick; Andia Biraro, Irene; Byakika-Kibwika, Pauline; Kamya, Moses R.The World Health Organization recommends antiretroviral therapy (ART) for all HIV-infected patients at all CD4 counts. However, there are concerns that asymptomatic patients may have poorer viral suppression and high attrition. Objectives: We sought to determine attrition and viral suppression among healthy HIV-infected patients initiated on ART in program settings. Methods: This cross-sectional study enrolled ART-experienced patients attending two PEPFAR-supported, high-volume clinics in Kampala, Uganda. Eligible patients were >18 years and had completed at least six months on ART. Participants were interviewed on socio-demographics, ART history and plasma viral load (VL) determined using Abbott Real-time. Predictors of viral suppression (<75 copies/ml) were determined using multivariate logistic regression.Item Nitrogen-neutrality: a step towards sustainability(Environmental Research Letters, 2014) Leip, Adrian; Leach, Allison; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Tenywa, John Stephen; Mudiope, Joseph; Hutton, Olivia; Cordovil, Claudia M d S; Bekunda, MateeteWe propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference's N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.Item Soil Organic Carbon Thresholds and Nitrogen Management in Tropical Agroecosystems: Concepts and Prospects(concepts and prospects., 2013) Musinguzi, Patrick; Tenywa, John Stephen; Ebanyat, Peter; Tenywa, Moses Makooma; Mubiru, Drake N.; Basamba, Twaha Ali; Leip, AdrianSoil organic carbon (SOC) is a potential soil fertility indicator for regulating nitrogen application in tropical farming systems. However, there are limited studies that have discussed SOC thresholds above or below which crop production could be diminished, or at which no or high response to nitrogen (N) application can be realized. This review explores the drivers of SOC concentration relevant for the establishment of thresholds. We further evaluate existing SOC thresholds for provoking no yield response or significant response to added N fertilizer. Key drivers for SOC concentration relevant in establishing thresholds are mainly climate, topography, texture, and land use management. Soil organic carbon threshold for sustaining soil quality is widely suggested to be about 2% below which deterioration may occur. For added N fertilizer management, specific SOC thresholds seem quite complex and are only valid after assuming other factors are non-limiting. In some soils, SOC levels as low as 0.5% result in fertilizer responses and soils as high as 2% SOC also respond to small N doses. Minimum SOC thresholds can be identified for a given soil type, but maximum thresholds depend on crop N requirements, crop N use efficiency and amount of N applied. However, there seem to exist critical total SOC ranges that could be targeted for optimal indigenous N supply and integrative soil functional benefits. These can be targeted as minimum levels in soil fertility restoration. In all, it is still difficult to establish a single minimum or maximum SOC threshold value that can be universally or regionally acceptedItem Soil organic fractions in cultivated and uncultivated Ferralsols in Uganda(Geoderma Regional, 2015) Musinguzi, Patrick; Tenywa, John Stephen; Ebanyat, Peter; Basamba, Twaha Ali; Tenywa, Moses Makooma; Mubiru, Drake N.; Zinn, Yuri L.Ferralsols are chemically poor soils, with management challenges associated with soil fertility heterogeneity and nitrogen limitations. Proper assessment of soil organic matter fractions can be instrumental in understanding the causes of limited nitrogen supply, and thus addressing soil fertility heterogeneity. A study was conducted in cultivated and uncultivated Ferralsols, in order to assay soil organic carbon (SOC), its particle-size fractions and their influence on soil fertility heterogeneity across small farms in central Uganda. Soil samples were taken from the 0–15 and 15–30 cm depths from 30 cultivated fields classified as of low fertility, medium fertility and high fertility, and from two nearby sites in a native shrubland as references. Soil samples were physically fractionated into sand (2000–63 μm), silt (63–2 μm) and clay (< 2 μm). Total SOC and N were analyzed in bulk samples and each size fraction, and the Carbon Management Index (CMI), a widely used indicator of soil quality, was calculated for each field. The CMI in cultivated soils was far below the 100% in reference soils, reaching 34.7, 40.3 and 87% in low, medium and high fertility fields, respectively. SOC and N concentrations decreased in particle-size separates in the order clay > silt > sand. The SOC pool and N in the clay-sized fraction were correlated to soil fertility indicators. More N was stored in the silt + clay size fractions, a generally more stable pool, than in the more labile sand-sized pool. The SOC pool in sand size fractions was far below in low and medium fertility soils than in a reference uncultivated soil. Thus, the sand-sized pool emerged as the most likely cause of limited N supply in cultivated low-input Ferralsols in Uganda.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.Item Using DSSAT-CENTURY Model to Simulate Soil Organic Carbon Dynamics Under a Low-Input Maize Cropping System(2014) Musinguzi, Patrick; Ebanyat, Peter; Tenywa, John Stephen; Mwanjalolo, Majaliwa; Basamba, Twaha Ali; Tenywa, Moses M; Porter, CherylDecline in Soil Organic Carbon (SOC) below the critical levels is one of the major indicators of soil fertility depletion in Sub-Saharan Africa (SSA), with the main causes being poor management practices coupled with low input use. Measures for monitoring long-term impacts of management on SOC dynamics and its restoration can be critical in enhancing sustainable soil productivity. Crop models have proved to be good tools for understanding the influence of management options on soil and crop productivity. The DSSAT-Century model was applied to simulate the influence of management practices on SOC dynamics. Using long-term datasets from Kabete, Kenya (1976-1996 maize-bean) and Kiboga-Uganda (1980-2010 maize), model calibration and evaluation showed a good fit between simulated and observed values of SOC. On simulating continuous tillage with no fertilization for the 1980-2010 antecedent period and 2010-2060 extrapolated period, the model showed high rates of SOC decline in the newly cultivated soil as compared to a degraded soil. The simulated rate of decline is 2129 kg ha-1 yr-1 for newly cultivated soil and 849 kg ha-1 yr-1 for the continuously cultivated soils. The model was sensitive to initial partitioning of SOC pools, with SOC in previously uncultivated soils declining at a higher rate than that in the cultivated ones. The model confirmed that use of continuous tillage is a major threat to SOC building and soil fertility restoration in the tropics. Adopting conservation agriculture is critical for future generations. Overall, the DSSAT CENTURY model is a potential tool for predicting SOC dynamics in low-input farming systems.