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Papers by John Baptist Tumuhairwe

CRC Press eBooks, Apr 18, 2024

Biomass & Bioenergy, Nov 1, 2020

It is important, prior to application of organic wastes to land, that pathogen loads are reduced ... more It is important, prior to application of organic wastes to land, that pathogen loads are reduced sufficiently to minimize dissemination to the wider environment. Anaerobic digestion for biogas production is a low-cost method to reduce pathogens in agricultural wastes that provides the added benefits of energy generation. There have been claims of pathogen reduction following installation of biogas digesters in homesteads in Sub-Saharan Africa. Homestead pathogen levels following installation of the different designs of biogas digester were monitored using faecal indicator organisms within small rural farms in Ethiopia. However, different designs of digesters have registered varying levels of success. Of the three digester designs considered, fixed dome, floating drum and flexible balloon, the fixed dome design achieved the highest reductions in indicator organisms (coliforms, Escherichia coli and Enterococci) from feedstock to digestate; this is likely to be due its longer hydraulic retention time. Households with biogas digesters installed had significantly (p < 0.05) lower levels of coliforms, E. coli and Enterococci detected in the environment inside and outside the house area. However, in the same households, there was a significant (p < 0.05) increase in indicator organisms on the surface and handles of doors, indicating the potential for spread of pathogens on contaminated hands to door handles from handling the animal waste feedstock. This therefore, suggests the need for proper hand washing regimes after handling of feedstocks for biogas digesters.

Springer eBooks, Oct 15, 2007

Crop yields in Uganda are severely limited by declining soil fertility. Nitrogen (N), phosphorus ... more Crop yields in Uganda are severely limited by declining soil fertility. Nitrogen (N), phosphorus (P) and soil organic matter (SOM) are the most limiting factors, yet legume green manures are known to fix N2 and increase SOM. Legume green manure technology has proved suitable for smallholder and subsistence farmers in sub-Saharan Africa. In Uganda, the spread of the technology has so far been concentrated in the central and eastern part of the country. Therefore, this study aimed at scaling out the legume green manure technology in the western semi-arid and cattle corridor zone of Uganda through on-farm researcher-designed, researcher/farmer managed village trials. For this purpose the six legumes namely Crotalaria grahamiana, Crotalaria ochroleuca, Mucuna pruriens, Canavalia ensiformis, Lablab purpureum and Tephrosia vogelli were tested in plot of 10 m by 10 m in a randomized complete block design whereby each farm site represented a replicate. Six months after planting of the legumes, farmers were individually asked to select their preferred species and to name the reasons for their choice. Subsequently, the legume biomass was determined and incorporated in the soil prior to planting maize. C. ensiformis and T. vogelli were the most and least preferred species, respectively, C. ensiformsis yielded the highest (5.2 t ha-1) and T. vogelli the lowest (2.0 t ha-1) biomass. Highest maize grain yields were obtained from plots of M. pruriens (3.5 t ha-1), but they were not significantly different from those of C. ensiformis with 3.4 t ha-1. Incorporation of the natural fallow vegetation led to the lowest maize grain yields (1.9 tha-1).

American Journal of Plant Sciences, 2020

Cowpea (Vigna unguiculata) is an important legume crop in the tropics and subtropical regions of ... more Cowpea (Vigna unguiculata) is an important legume crop in the tropics and subtropical regions of the world. It is mainly grown for its leaves and grains, and to a lesser extent as a fodder crop. Cowpea is considered as the most important food grain legume in the dry savannas of tropical Africa. This study compared the yield of local (Agondire) and improved (SECOW 2W) cowpea varieties grown on an Oxisol. Inorganic P at levels of 0, 10, 20, and 40 kg•ha −1 was tested on each variety with or without rhizobia inoculation. The experiments were set up in a randomized complete block design and replicated thrice during the short and long rains of the 2015/2016 seasons on fifteen fields in Arua district, northern Uganda. Agondire responded significantly (P < 0.05) better than SECOW 2W when high rates of inorganic phosphorus (40 kg P ha −1) were applied. A significant increase of 26.4% and 28.4% in grain yield of Agondire and SECOW 2W, respectively was obtained after inoculation with rhizobia. We concluded that inoculation and P fertilizer application increased the yield of both varieties, but with inoculation, SECOW 2W performs much better at lower P fertilizer rates than Agondire. Therefore, we recommend growing of SECOW 2W under inoculation with 20 kg P ha −1 and an application of 40 kg P ha −1 for Agondire local cowpea variety in northern Uganda.

EGU General Assembly Conference Abstracts, Apr 1, 2019

International Journal of Agriculture Innovations and Research, 2015

Applied Soil Ecology, 2018

Unravelling how earthworms and ants are deterministically structured by abiotic and biotic factor... more Unravelling how earthworms and ants are deterministically structured by abiotic and biotic factors is of utmost relevance in fostering favourable environments for their increased abundance and action, more so in the increasingly degraded agricultural ecosystems of mountainous regions in sub-Saharan Africa. The Mount Elgon region (MER) of Uganda is characterised by mosaics of farmlands dominated by Arabica coffee with variability in inclusion of companion crops and shade trees, and in use of organic and inorganic fertilizers; and elevation. In this paper we explored abundance of soil macrofauna and microclimate patterns in different cropping systems at varying mountain elevations. The study covered 72 coffee fields delineated by 3 elevation categories: low, mid and high; and 4 cropping systems: Coffee monocrop (C), Coffee + annual crop (C + A), coffee + banana (C + B), and coffee + banana + shade trees (C + B + T). Results indicated that ant abundance at high elevation was thrice that of low and was same order of magnitude in unshaded than in banana-and tree-shaded systems. Earthworm abundance followed a different trend, decreasing with altitude except in C + B and C + A systems. Some of these relationships could be explained by ambient temperature, light intensity and soil electrical conductivity in the systems. Earthworms preferred less-illuminated shaded coffee systems at warmer low-mid elevations and soils with relatively high electrical conductivity whereas ants' counts were depressed by such systems, and mostly driven by cooler higher elevations. These results show that agricultural practices at the field scale have notable impact on abundance of macrofauna that provide ecosystem services and need consideration when working towards sustainability.

Journal of Agricultural Science and Food Technology, 2021

A screen house pot study using bio-slurry at the rate of 7.8 t N / ha was conducted at Makerere U... more A screen house pot study using bio-slurry at the rate of 7.8 t N / ha was conducted at Makerere University Agricultural Research Institute (MAURIK) Kabanyolo, Uganda. This was monitored using fecal indicator organisms (coliforms, Escherichia coli and Enterococci) in loamy sand, sandy loam and sandy clay loam texture obtained at the study site within 5litres pots under a Complete Randomized Design under a screenhouse. The different textures significantly (p<0.05) reduced the fecal indicator organisms. Conditions within the loamy sand texture reduced the pathogenic microorganisms within 90 days due to its high sand content. In this soil texture, E. coli and enterococci were reduced to undetectable levels within 90 days unlike the coliforms. Fecal, Bio slurry, coliforms, Escherichia. coli, Enterococci

Agriculture & Food Security

Agricultural intensification continues in Africa in attempts to meet the rising food demands of t... more Agricultural intensification continues in Africa in attempts to meet the rising food demands of the equally rising population. However, most arable lands in the region are characterized by nutrient deficiency and over-reliance on synthetic fertilizers which consequently contributes to increased production costs, environmental pollution, and global warming. Decades of research on plant–rhizobacterial interactions have led to the formulation and commercialization of rhizobacterial biofertilizers globally for sustainable soil and crop health. Nevertheless, this promising technology has not received much attention in Africa and remains largely unexplored due to several constraints. This article discusses the practical applications of rhizobacterial biofertilizers for sustainable crop production in sub-Saharan Africa. The challenges of soil infertility and the use of conventional synthetic fertilizers in crop production in Africa are critically evaluated. An overview of the potential of ...

International Journal of Soil Science, 2016

Frontiers in Soil Science

IntroductionFarming systems influence composition and abundance of microbial communities.Methodol... more IntroductionFarming systems influence composition and abundance of microbial communities.MethodologyA study was conducted using morphotyping and enumeration methods to determine the composition and spore abundance of Arbuscular Mycorrhizal Fungi (AMF) in sweet potato producing regions in eastern Uganda. Sampling was done from fields with crop types (CTs) including legumes (groundnuts, common beans, cowpea, soybeans, green grams), sorghum, sweet potato, and fallowed fields which were used as a control. Three agro-ecological zones (AEZs) i.e., Mt. Elgon High Farmlands (MEHF), Lake Victoria Crescent (LVC), and Southern and Eastern Lake Kyoga Basin (SELKB) were considered.Results and discussionA total of 6 AMF genera comprising of Glomus, Acaulospora, Scutellospora, Entrophospora, Archaeospora, and Gigaspora were isolated from the study sites. Agro-ecological zones had a significant (p<0.05) effect on Entrophospora spp. while crop types had a significant (p<0.05) effect on Gigaspo...

Frontiers in Soil Science

IntroductionFarming systems influence composition and abundance of microbial communities.Methodol... more IntroductionFarming systems influence composition and abundance of microbial communities.MethodologyA study was conducted using morphotyping and enumeration methods to determine the composition and spore abundance of Arbuscular Mycorrhizal Fungi (AMF) in sweet potato producing regions in eastern Uganda. Sampling was done from fields with crop types (CTs) including legumes (groundnuts, common beans, cowpea, soybeans, green grams), sorghum, sweet potato, and fallowed fields which were used as a control. Three agro-ecological zones (AEZs) i.e., Mt. Elgon High Farmlands (MEHF), Lake Victoria Crescent (LVC), and Southern and Eastern Lake Kyoga Basin (SELKB) were considered.Results and discussionA total of 6 AMF genera comprising of Glomus, Acaulospora, Scutellospora, Entrophospora, Archaeospora, and Gigaspora were isolated from the study sites. Agro-ecological zones had a significant (p<0.05) effect on Entrophospora spp. while crop types had a significant (p<0.05) effect on Gigaspo...

With contribution from: African Agricultural Technology Foundation (contact person: David Tarus);... more With contribution from: African Agricultural Technology Foundation (contact person: David Tarus); Ethiopian Institute of Agricultural Research (contact persons: Getahun Mitiku & Tesfaye Shimber),; Kwame Nkrumah University of Science and Technologies in Ghana (contact person: Robert Abaidoo); Egerton University in Kenya (contact person: Nancy Mungai); Institute of Agricultural Research at Ahmadu Bello University in Nigeria (contact person: Ado Yusuf); Sokoine University of Agriculture in Tanzania (contact person: Konsolatha Mhaiki); and Makerere University in Uganda (contact person: John Baptist Tumuhairwe).

Land

Maize (Zea mays L.) productivity is constrained by water shortages in the predominantly rainfed a... more Maize (Zea mays L.) productivity is constrained by water shortages in the predominantly rainfed agriculture of the tropical semi-arid Ruzizi Plain, in the eastern Democratic Republic of Congo (DRC). The region is characterized by a high seasonal and inter-annual rainfall variability and a frequent occurrence of consecutive dry days within growing seasons. Consequently, planning water utilization in rainfed agriculture has become complex, as appropriate soil water conservation (SWC) practices are lacking among most smallholder farmers. Identifying practices that increase water use efficiency (WUE) along the slope gradient is crucial for supporting maize production in the region. In this study, we assessed, for three growing seasons, the effectiveness of two SWC practices (tied ridges and Zai pits) in improving the WUE of two maize varieties along three slope gradients (0–2, 2–8, and 8–15%) in the tropical semi-arid Ruzizi Plain. In this area, rainfall amounts (142–289 mm) were consis...

Journal of Crop Science and Biotechnology, 2017

The high protein content of soybean (Glycine max) seeds results in high nitrogen demand, causing ... more The high protein content of soybean (Glycine max) seeds results in high nitrogen demand, causing a huge nitrogen uptake during plant growth. As a legume crop, soybean can fix atmospheric N through symbiotic associations with Bradyrhizobia and perform well in African nitrogen poor soils. This study aimed at establishing the ability of promiscuous soybean genotypes to fix nitrogen and devise the relationship between nodule scores and amount of nitrogen fixed. Twelve soybean genotypes were inoculated with Bradyrhizobium japonicum Strain USDA 110 (specific) and Bradyrhizobium sp. Strain USDA 3456 (native) and raised in pots in a greenhouse. At the R3.5 growth stage, nodules were scored and xylem sap was extracted, which xylem sap was used to carry out ureide, amino-N, and nitrates assays. The relative abundance of ureide was used to devise the proportion of nitrogen fixed by each genotype. The proportion of nitrogen derived from atmospheric N 2 (Ndfa) ranged from 47.9 to 78.8% under USDA 3456 and from 36.7 to 78.7% under USDA 110. A strong correlation was found between nodule scores, especially nodules' effectiveness, and Ndfa. The genotypes Wondersoya (78.8%), Maksoy 2N (78.4%), Namsoy 3 (78.3%), and Maksoy 3N (75.7%) had high nitrogen-fixing ability in response to USDA 3456. Promiscuous soybean genotypes can fix nitrogen equally under both native and specific Bradyrhizobium types. Nodules' effectiveness can be a good predictor of biological nitrogen fixation. This study highlighted that crop improvement to boost soybean production in Africa should target promiscuous varieties for better yield with less inputs.

CRC Press eBooks, Apr 18, 2024

Biomass & Bioenergy, Nov 1, 2020

It is important, prior to application of organic wastes to land, that pathogen loads are reduced ... more It is important, prior to application of organic wastes to land, that pathogen loads are reduced sufficiently to minimize dissemination to the wider environment. Anaerobic digestion for biogas production is a low-cost method to reduce pathogens in agricultural wastes that provides the added benefits of energy generation. There have been claims of pathogen reduction following installation of biogas digesters in homesteads in Sub-Saharan Africa. Homestead pathogen levels following installation of the different designs of biogas digester were monitored using faecal indicator organisms within small rural farms in Ethiopia. However, different designs of digesters have registered varying levels of success. Of the three digester designs considered, fixed dome, floating drum and flexible balloon, the fixed dome design achieved the highest reductions in indicator organisms (coliforms, Escherichia coli and Enterococci) from feedstock to digestate; this is likely to be due its longer hydraulic retention time. Households with biogas digesters installed had significantly (p < 0.05) lower levels of coliforms, E. coli and Enterococci detected in the environment inside and outside the house area. However, in the same households, there was a significant (p < 0.05) increase in indicator organisms on the surface and handles of doors, indicating the potential for spread of pathogens on contaminated hands to door handles from handling the animal waste feedstock. This therefore, suggests the need for proper hand washing regimes after handling of feedstocks for biogas digesters.

Springer eBooks, Oct 15, 2007

Crop yields in Uganda are severely limited by declining soil fertility. Nitrogen (N), phosphorus ... more Crop yields in Uganda are severely limited by declining soil fertility. Nitrogen (N), phosphorus (P) and soil organic matter (SOM) are the most limiting factors, yet legume green manures are known to fix N2 and increase SOM. Legume green manure technology has proved suitable for smallholder and subsistence farmers in sub-Saharan Africa. In Uganda, the spread of the technology has so far been concentrated in the central and eastern part of the country. Therefore, this study aimed at scaling out the legume green manure technology in the western semi-arid and cattle corridor zone of Uganda through on-farm researcher-designed, researcher/farmer managed village trials. For this purpose the six legumes namely Crotalaria grahamiana, Crotalaria ochroleuca, Mucuna pruriens, Canavalia ensiformis, Lablab purpureum and Tephrosia vogelli were tested in plot of 10 m by 10 m in a randomized complete block design whereby each farm site represented a replicate. Six months after planting of the legumes, farmers were individually asked to select their preferred species and to name the reasons for their choice. Subsequently, the legume biomass was determined and incorporated in the soil prior to planting maize. C. ensiformis and T. vogelli were the most and least preferred species, respectively, C. ensiformsis yielded the highest (5.2 t ha-1) and T. vogelli the lowest (2.0 t ha-1) biomass. Highest maize grain yields were obtained from plots of M. pruriens (3.5 t ha-1), but they were not significantly different from those of C. ensiformis with 3.4 t ha-1. Incorporation of the natural fallow vegetation led to the lowest maize grain yields (1.9 tha-1).

American Journal of Plant Sciences, 2020

Cowpea (Vigna unguiculata) is an important legume crop in the tropics and subtropical regions of ... more Cowpea (Vigna unguiculata) is an important legume crop in the tropics and subtropical regions of the world. It is mainly grown for its leaves and grains, and to a lesser extent as a fodder crop. Cowpea is considered as the most important food grain legume in the dry savannas of tropical Africa. This study compared the yield of local (Agondire) and improved (SECOW 2W) cowpea varieties grown on an Oxisol. Inorganic P at levels of 0, 10, 20, and 40 kg•ha −1 was tested on each variety with or without rhizobia inoculation. The experiments were set up in a randomized complete block design and replicated thrice during the short and long rains of the 2015/2016 seasons on fifteen fields in Arua district, northern Uganda. Agondire responded significantly (P < 0.05) better than SECOW 2W when high rates of inorganic phosphorus (40 kg P ha −1) were applied. A significant increase of 26.4% and 28.4% in grain yield of Agondire and SECOW 2W, respectively was obtained after inoculation with rhizobia. We concluded that inoculation and P fertilizer application increased the yield of both varieties, but with inoculation, SECOW 2W performs much better at lower P fertilizer rates than Agondire. Therefore, we recommend growing of SECOW 2W under inoculation with 20 kg P ha −1 and an application of 40 kg P ha −1 for Agondire local cowpea variety in northern Uganda.

EGU General Assembly Conference Abstracts, Apr 1, 2019

International Journal of Agriculture Innovations and Research, 2015

Applied Soil Ecology, 2018

Unravelling how earthworms and ants are deterministically structured by abiotic and biotic factor... more Unravelling how earthworms and ants are deterministically structured by abiotic and biotic factors is of utmost relevance in fostering favourable environments for their increased abundance and action, more so in the increasingly degraded agricultural ecosystems of mountainous regions in sub-Saharan Africa. The Mount Elgon region (MER) of Uganda is characterised by mosaics of farmlands dominated by Arabica coffee with variability in inclusion of companion crops and shade trees, and in use of organic and inorganic fertilizers; and elevation. In this paper we explored abundance of soil macrofauna and microclimate patterns in different cropping systems at varying mountain elevations. The study covered 72 coffee fields delineated by 3 elevation categories: low, mid and high; and 4 cropping systems: Coffee monocrop (C), Coffee + annual crop (C + A), coffee + banana (C + B), and coffee + banana + shade trees (C + B + T). Results indicated that ant abundance at high elevation was thrice that of low and was same order of magnitude in unshaded than in banana-and tree-shaded systems. Earthworm abundance followed a different trend, decreasing with altitude except in C + B and C + A systems. Some of these relationships could be explained by ambient temperature, light intensity and soil electrical conductivity in the systems. Earthworms preferred less-illuminated shaded coffee systems at warmer low-mid elevations and soils with relatively high electrical conductivity whereas ants' counts were depressed by such systems, and mostly driven by cooler higher elevations. These results show that agricultural practices at the field scale have notable impact on abundance of macrofauna that provide ecosystem services and need consideration when working towards sustainability.

Journal of Agricultural Science and Food Technology, 2021

A screen house pot study using bio-slurry at the rate of 7.8 t N / ha was conducted at Makerere U... more A screen house pot study using bio-slurry at the rate of 7.8 t N / ha was conducted at Makerere University Agricultural Research Institute (MAURIK) Kabanyolo, Uganda. This was monitored using fecal indicator organisms (coliforms, Escherichia coli and Enterococci) in loamy sand, sandy loam and sandy clay loam texture obtained at the study site within 5litres pots under a Complete Randomized Design under a screenhouse. The different textures significantly (p<0.05) reduced the fecal indicator organisms. Conditions within the loamy sand texture reduced the pathogenic microorganisms within 90 days due to its high sand content. In this soil texture, E. coli and enterococci were reduced to undetectable levels within 90 days unlike the coliforms. Fecal, Bio slurry, coliforms, Escherichia. coli, Enterococci

Agriculture & Food Security

Agricultural intensification continues in Africa in attempts to meet the rising food demands of t... more Agricultural intensification continues in Africa in attempts to meet the rising food demands of the equally rising population. However, most arable lands in the region are characterized by nutrient deficiency and over-reliance on synthetic fertilizers which consequently contributes to increased production costs, environmental pollution, and global warming. Decades of research on plant–rhizobacterial interactions have led to the formulation and commercialization of rhizobacterial biofertilizers globally for sustainable soil and crop health. Nevertheless, this promising technology has not received much attention in Africa and remains largely unexplored due to several constraints. This article discusses the practical applications of rhizobacterial biofertilizers for sustainable crop production in sub-Saharan Africa. The challenges of soil infertility and the use of conventional synthetic fertilizers in crop production in Africa are critically evaluated. An overview of the potential of ...

International Journal of Soil Science, 2016

Frontiers in Soil Science

IntroductionFarming systems influence composition and abundance of microbial communities.Methodol... more IntroductionFarming systems influence composition and abundance of microbial communities.MethodologyA study was conducted using morphotyping and enumeration methods to determine the composition and spore abundance of Arbuscular Mycorrhizal Fungi (AMF) in sweet potato producing regions in eastern Uganda. Sampling was done from fields with crop types (CTs) including legumes (groundnuts, common beans, cowpea, soybeans, green grams), sorghum, sweet potato, and fallowed fields which were used as a control. Three agro-ecological zones (AEZs) i.e., Mt. Elgon High Farmlands (MEHF), Lake Victoria Crescent (LVC), and Southern and Eastern Lake Kyoga Basin (SELKB) were considered.Results and discussionA total of 6 AMF genera comprising of Glomus, Acaulospora, Scutellospora, Entrophospora, Archaeospora, and Gigaspora were isolated from the study sites. Agro-ecological zones had a significant (p<0.05) effect on Entrophospora spp. while crop types had a significant (p<0.05) effect on Gigaspo...

Frontiers in Soil Science

IntroductionFarming systems influence composition and abundance of microbial communities.Methodol... more IntroductionFarming systems influence composition and abundance of microbial communities.MethodologyA study was conducted using morphotyping and enumeration methods to determine the composition and spore abundance of Arbuscular Mycorrhizal Fungi (AMF) in sweet potato producing regions in eastern Uganda. Sampling was done from fields with crop types (CTs) including legumes (groundnuts, common beans, cowpea, soybeans, green grams), sorghum, sweet potato, and fallowed fields which were used as a control. Three agro-ecological zones (AEZs) i.e., Mt. Elgon High Farmlands (MEHF), Lake Victoria Crescent (LVC), and Southern and Eastern Lake Kyoga Basin (SELKB) were considered.Results and discussionA total of 6 AMF genera comprising of Glomus, Acaulospora, Scutellospora, Entrophospora, Archaeospora, and Gigaspora were isolated from the study sites. Agro-ecological zones had a significant (p<0.05) effect on Entrophospora spp. while crop types had a significant (p<0.05) effect on Gigaspo...

With contribution from: African Agricultural Technology Foundation (contact person: David Tarus);... more With contribution from: African Agricultural Technology Foundation (contact person: David Tarus); Ethiopian Institute of Agricultural Research (contact persons: Getahun Mitiku & Tesfaye Shimber),; Kwame Nkrumah University of Science and Technologies in Ghana (contact person: Robert Abaidoo); Egerton University in Kenya (contact person: Nancy Mungai); Institute of Agricultural Research at Ahmadu Bello University in Nigeria (contact person: Ado Yusuf); Sokoine University of Agriculture in Tanzania (contact person: Konsolatha Mhaiki); and Makerere University in Uganda (contact person: John Baptist Tumuhairwe).

Land

Maize (Zea mays L.) productivity is constrained by water shortages in the predominantly rainfed a... more Maize (Zea mays L.) productivity is constrained by water shortages in the predominantly rainfed agriculture of the tropical semi-arid Ruzizi Plain, in the eastern Democratic Republic of Congo (DRC). The region is characterized by a high seasonal and inter-annual rainfall variability and a frequent occurrence of consecutive dry days within growing seasons. Consequently, planning water utilization in rainfed agriculture has become complex, as appropriate soil water conservation (SWC) practices are lacking among most smallholder farmers. Identifying practices that increase water use efficiency (WUE) along the slope gradient is crucial for supporting maize production in the region. In this study, we assessed, for three growing seasons, the effectiveness of two SWC practices (tied ridges and Zai pits) in improving the WUE of two maize varieties along three slope gradients (0–2, 2–8, and 8–15%) in the tropical semi-arid Ruzizi Plain. In this area, rainfall amounts (142–289 mm) were consis...

Journal of Crop Science and Biotechnology, 2017

The high protein content of soybean (Glycine max) seeds results in high nitrogen demand, causing ... more The high protein content of soybean (Glycine max) seeds results in high nitrogen demand, causing a huge nitrogen uptake during plant growth. As a legume crop, soybean can fix atmospheric N through symbiotic associations with Bradyrhizobia and perform well in African nitrogen poor soils. This study aimed at establishing the ability of promiscuous soybean genotypes to fix nitrogen and devise the relationship between nodule scores and amount of nitrogen fixed. Twelve soybean genotypes were inoculated with Bradyrhizobium japonicum Strain USDA 110 (specific) and Bradyrhizobium sp. Strain USDA 3456 (native) and raised in pots in a greenhouse. At the R3.5 growth stage, nodules were scored and xylem sap was extracted, which xylem sap was used to carry out ureide, amino-N, and nitrates assays. The relative abundance of ureide was used to devise the proportion of nitrogen fixed by each genotype. The proportion of nitrogen derived from atmospheric N 2 (Ndfa) ranged from 47.9 to 78.8% under USDA 3456 and from 36.7 to 78.7% under USDA 110. A strong correlation was found between nodule scores, especially nodules' effectiveness, and Ndfa. The genotypes Wondersoya (78.8%), Maksoy 2N (78.4%), Namsoy 3 (78.3%), and Maksoy 3N (75.7%) had high nitrogen-fixing ability in response to USDA 3456. Promiscuous soybean genotypes can fix nitrogen equally under both native and specific Bradyrhizobium types. Nodules' effectiveness can be a good predictor of biological nitrogen fixation. This study highlighted that crop improvement to boost soybean production in Africa should target promiscuous varieties for better yield with less inputs.