Department of Soil Science and Irrigation Management

Permanent URI for this communityhttps://hdl.handle.net/20.500.12504/193

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Soil moisture dynamics under different tillage practices in cassava–sorghum based cropping systems in eastern Uganda
(Elsevier: Ecohydrology & Hydrobiology, 2013) Mulebeke, Robert; Kironchi, Geoffrey; Tenywa, Moses M.
Soil moisture storage in the root zone determines availability of water in crop production, but there is limited attention on water resource management in cassava–sorghum production systems. Soil moisture content was higher under ripping than mouldboard ploughing. Mouldboard ploughed plots had more moisture in the upper (0–10 cm) layer while, the ripped plots accumulated more moisture in the lower (20–40 cm) root zone. Soil surface roughness was stable two months after ploughing. Crop combinations and seasons influenced soil moisture storage over the growing period. The different cropping systems vary in their soil moisture extraction capacities at different growth stages, hence influencing the overall moisture storage and water used in the root zone.
Soil organic carbon and nitrogen decomposition in fecal manure of cattle fed browse/maize silages
(Sustainable Agriculture Research, 2014) Kato, , Habib; Mulebeke, Robert; Bareeba, Felix Budara; Sabiiti, Elly Nyambobo
Soil organic carbon (C) and nitrogen (N) decomposition in fecal manure of cattle fed browses of Calliandra (Calliandra calothyrsus), Gliricidia (Gliricidia sepium) and Leucaena (Leucaena leucocephala) browse/maize silage mixtures and maize (Zea mays) silage alone when applied to the soil were investigated in a pot experiment in comparison to the corresponding silages fed. Maize silage alone had the lowest N and a larger C: N ratio, making it a poor quality compost when applied to the soil, but compared to the browse/maize silage mixtures it had the highest level of soluble N as non-protein nitrogen (NPN) which makes much of its N available for soil microbial decomposition of its organic C. Calliandra browse/maize silage mixture had the highest level of fiber-bound N (ADFN), which reduces N availability for soil microbial decomposition of its organic C in spite of its high N content and a narrower C: N ratio. Fecal manure from maize silage alone had a lower level of N and a wider C: N ratio than fecal manure from the other silages fed which would affect its decomposition in the soil, but it had the lowest level of ADFN and much of its N is made available for soil microbial decomposition of its organic C. Soil samples after 12 weeks of the experiment showed that Calliandra browse/maize silage mixture maintained the highest level of C in the soil, while maize silage alone maintained the lowest level. Also soils treated with fecal manure from the other browse/maize silage mixtures maintained higher levels of C than fecal manure from maize silage alone. Organic C levels were lowest at 8 weeks of the experiment for all treatments and rose to the original levels at 12 weeks which could have been as a result of biotic and hydrologic factors coupled with soil aggregation. Decomposition of organic N followed a similar trend as organic C. The two elements are linked in both plant inputs in the soil and in the eventual soil humic substances. The soils treated with browse/maize silage mixtures maintained C: N ratios that were similar to that of the control soil and higher than those of the fecal manure treatments. Thus, in spite of the added silage materials to the soil, rapid decomposition of organic C could not occur to reflect benefits of adding the silage materials to the soil. Thus, fecal manure, particularly from feeding animals on browse/forage diets is more beneficial in the soil as it would decompose more readily releasing the plant nutrients they contain.
Response of common bean genotypes grown in soil with normal or limited moisture, with special reference to the nutrient phosphorus
(MDPI : Agronomy, 2018-07-30) Namugwanya, Margaret; Tenywa, John Stephen; Otabbong, Erasmus
Drought and phosphorus deficiency in the soil are the major production limitations of common beans (Phaseolus vulgaris L.) in Sub-Saharan Africa. This study measured the yield responses of low phosphorus-tolerant common beans to drought stress. A field experiment was conducted under two drought conditions codenamed, non-drought-stress (NDS) and drought-stress (DS). The former was located at Mukono Zonal Agricultural Research and Development Institute (MUZARDI) in Mukono District, characterised by rainfall of more than 400 mm season−1. The latter was situated at Wabinyonyi in Nakasongola District, characterised by less than 300 mm season−1; both in central Uganda. Treatments included the two study conditions (NDS and DS); and four test bean genotypes, AFR703-1, AFR 708, JESCA, and MCM 2001, against a local check, K131. A water deficit of 156 mm season−1 was observed in the DS site causing a drought intensity index (DII) of 40%. That pattern contrasted considerably in the NDS site where the actual rainfall did not significantly (p > 0.05) vary from the required water by the bean plant. Whereas genotypes AFR703-1 and AFR708 out-yielded the local check in NDS by 213 and 681 kg ha−1, respectively; their grain yield harvested was comparable to the control yield in DS. When grown under DS, low P-tolerant beans, especially the AFR703-1 and AFR708, survived drought stress through faster development by reducing the number of days to flower, reach physiological maturity and develop seeds. AFR703-1 and AFR708 sufficiently withstand drought stress, and are therefore recommended for inclusion in cropping systems that are characteristically constrained by the combined soils’ P deficiency and/or drought.
Effectiveness of group extension methods in promoting high quality cassava flour production among smallholder farmers in Apac district, Uganda
(Kyambogo university (unpublished work), 2018-11) Gobo, Denis
Smallholder farmers of Apac District received advice from extension agents on the production of high quality cassava flour from 2009 to 2015. Despite training, production remained low at 4000kg ha·1 compared to the expected output of 8000kg ha· 1 , which called for an investigation conceived to establish the effectiveness of the group extension methods used in training for high output. A cross sectional survey design was used. Interviews, questionnaires, observations and focused group discussions were used to collect data from a total of 133 respondents consisting of 126 farmers randomly selected from 185 farmers trained. Additionally, seven extension agents completed questionnaires and were interviewed. Using SPSS version 16.0, the data collected was processed to determine frequencies, percentages, cross tabulations and chi-square test. Results show 64% of the famers participated in demonstrations, 73% in field days and 75% in exchange visits. Cross tabulations showed that demonstrations benefited 59% of the farmers in using clean water for processing; field days benefited 65% of the farmers in practicing timely harvesting and exchange visits benefited only 19% in using recommended varieties at planting. The framers whose flour was rejected at sale were: 20% for lack of follow up after training, 14% for reduced training hours and 13% for high speed content delivery. Chi-square showed significant association at O.Ola between farmers participation in demonstrations and knowledge in site selection for cassava production. Most farmers acquired more knowledge from group demonstrations, followed by field days and exchange visits respectively. Methods were effective in practices such as site selection, timely harvesting, use of clean water but not effective in post-harvest handling. Trainers of farmers should keep group size to 6 while combining methods for chipping and post-harvest handling. Time duration and frequency of training should be optimum farmers to produce high quality cassava flour.
Reactions of pineapple cultivars to pineapple heart rot disease in central Uganda
(Elsevier: Crop Protection., 2020-09) Oculi, J.; Bua, B.; Ocwa, A.
Pineapple (Ananas comosus (L.) Merr.) is an important fruit crop in Uganda ranking third as a major fruit crop after banana and citrus globally. However, pineapple production in Uganda is threatened by the recent outbreaks of pineapple heart rot disease (PHRD). Pineapple heart rot disease is the most widespread and devastating disease of pineapple in Uganda and can cause tremendous yield loss. Information on the sources of resistance is still scanty in Uganda. Additionally, no study has been done in Uganda which point out whether variety influences disease severity. Therefore, the objective of this study was to assess the reaction of pineapple cultivars to pineapple heart rot disease in central Uganda. Five cultivars of healthy pineapple suckers were planted in the field in a randomized complete block design (RCBD) to screen for resistance to PHRD. No significant (p > 0.05) difference in PHRD incidence was recorded in week two and week 4 of the experiment. However, there was significant difference (p < 0.001) in incidence of PHRD from week 6 up to week 12 of the experiment. Additionally, PHRD severity varied significantly (p < 0.001) from week 6 up to week 12. Cultivar Smooth Cayenne recorded low severity and is therefore promising. All the five pineapple cultivars were susceptible to PHRD though with varying levels of incidence and severity. Therefore, there is need for additional studies to establish the suitability of Smooth Cayenne as a source of parental donor in breeding for resistance to PHRD.
Review of the land use and climate change impact assessments in semi-arid ecosystems in Africa: Opportunities and challenges
(Water and Environmental Sustainability, 2023-12) Chisadza, Bright; Musinguzi, Simon Peter; Gwate, Onalenna; Malinga, Wayne
Despite the existing literature on climate variability (CV) and land use change (LUC) impact assessments, understanding their effectiveness in semi-arid regions remains challenging. This review aims to assess the effectiveness of CV and LUC impact assessments in guiding adaptation options for smallholder farmers in semi-arid ecosystems and associated challenges and opportunities. We conducted a systematic literature review, primarily using Google Scholar, to examine the impact of LUC and CV in African semi-arid ecosystems. We employed Vos Viewer to analyze the relationships among the identified sources. Our findings reveal that current assessment approaches often fall short in capturing the intricate interactions within semi-arid ecosystems. These assessments frequently emphasize biophysical productivity, employ reductionist modeling methods, and neglect the social, economic, and adaptive aspects of these systems. Our review underscores the importance of integrating CV and LUC in impact assessments. While a majority of studies concentrate on CV adaptation (26%), they often overlook the pivotal role of LUC and their interplay with climate impacts. Only a small fraction (2%) integrates CV and LUC in impact assessments. Assessing the benefits of CV and LUC impact assessments presents mixed results, particularly for smallholder farmers. While global and regional benefits are discernible, quantifying these advantages at the local smallholder farmer level remains challenging due to diversified land use and small-scale operations. This highlights the need for localized studies addressing the specific challenges confronting smallholder farmers in semi-arid regions. To enhance assessments effectiveness, we recommend for more interdisciplinary research and the application of a complex systems approach, integrating GIS and remote sensing.
Uncovering adaptive mechanisms to water deficit in low soil phosphorus tolerant common bean genotypes
(Food Agricultural Sciences and Technology (FAST), 2025-05-12) Namugwanya, Margaret; Taulya, Godfrey; Basamba, Twaha Ali; Tenwya, John Stephen
Water-Deficit and low soil phosphorus (P) are major constraints for common bean (Phaseolus vulgaris L.) cultivation in sub-Saharan Africa (SSA). Tolerant varieties offer cost-effective alternatives to irrigation and fertilizers. This study examines how low soil P-tolerant common bean genotypes adapt to Water-Deficit through leaf morphology, physiology, and root development in greenhouse and field conditions. AFR703-1, AFR708, and K131 were arranged in a completely randomized design under Well-Watered and Water-Deficit conditions, with P applied at 0, 6, and 16 mg P kg⁻¹ soil. In the field, identical genotypes were arranged in a randomized complete block design with P applied at 0, 12, and 32 kg P ha⁻¹ under Well-Watered and Water-Deficit Environments. AFR708 showed a significant (P < 0.001) reduction in RWC (26%) under Water-Deficit without P mitigated by higher P levels, while AFR703-1 and K131 showed no significant difference (P > 0.05) under similar conditions. AFR703-1 and K131 exhibited significantly (P < 0.05) lower specific leaf area in Water-Deficit than Well-Watered conditions, contrasting with AFR708. Similarly, LMR in the studied genotypes decreased (P < 0.001) and with rising P under Water-Deficit, with diverse trends in Well-Watered conditions. AFR703-1 and K131 recorded higher NAR in Water-Deficit than Well-Watered conditions, contrary to AFR708. AFR genotypes decreased significantly (P < 0.001) showed enhanced root development in Water- Deficit, including increased adventitious, tap, and lateral roots, higher total biomass, and finer root length compared to Well-Watered conditions, despite lower grain yields, notably in Nakasongola site. Overall, AFR703-1 holds promise as a breeding parent for enhancing Water-Deficit resilience and P tolerance in common bean production, despite yield reduction under stress conditions.
The effect of Nile perch bait fishery on the reproductive and biometric parameters of Mormyrus Kannume along the upper Victoria Nile
(Kyambogo University(Unpublished work), 2025-09) Mbaho, Eunith
The increased exploitation of Mormyrus Kannume using illegal fishing gear, used as bait to capture Nile perch, poses a threat to its population and could ultimately lead to its extinction. Monitoring of fish reproductive metrics is crucial for assessing population health, informing sustainable management practices, and ensuring the ecological balance of aquatic ecosystems. This study was carried out to; identify the socio-economic factors promoting the use of M. Kannume as a bait in the Nile perch fishery, determine its size at sexual maturity (L50) and sex ratios, and examine its biometric parameters (body length and body weight relationship) along the Upper Victoria Nile. The study was both qualitative and descriptive, where questionnaires were administered to respondents in person along selected landing sites on the Upper Victoria Nile and Lake Victoria. The sex ratio was calculated after identifying the sex of each sample following dissection. The L50 was determined by the maturity logistic ogive curve. The Total Length and body weight were measured using a measuring board and a calibrated weighing scale respectively. The results generated showed that the key socio-economic factors that influence the use of this bait were fishing experience, bait cost, selling price of Nile perch, bait type, and size of the bait. The chi-square test on sex ratio (females: males) showed no significant deviations from the normal indicating a healthy population structure. Size at sexual maturity L50, for males and females was 23 cm and 21 cm respectively indicating that the fish are maturing at a small length probably due to increased fishing pressure. The TL of the fish caught ranged from 10.5 cm to 67.5 cm (mean of 17.62 ± 0.11 cm), and the body weight ranged from 10.84 g to 2548.8 g (mean of 57.54 ± 2.52 g). The b value (LWR exponent) was 2.9 (Male) and 2.8 (female) indicating a negative allometric growth, implying that the fish are in a healthy condition but slightly underweight probably due to stress from fishing pressure. These results demonstrate that M. Kannume is facing reduced size at sexual maturity, and slight decline in the relationship between body length and body weight. These changes are probably due to fishing pressure and use of inappropriate fishing gear which may catch fish before they reach maturity. Captive breeding of M. Kannume is recommended to ease pressure on wild populations and ensure sustainable bait supply. Therefore, this study has highlighted the socio-economic driving factors in the use of M. Kannume as bait. Understanding M. Kannume’s biological data is important in the development of management strategies to address the already caused effects and preserve M. Kannume from extinction in the long run.
Influence of microbial inoculants on water use efficiency and yield in a watermelon in rain-fed cropping
(Kyambogo University(Unpublished work), 2025-10) Mpisa, Isaac
Smallholder rain fed systems in Uganda are often characterized by low productivity of watermelon crop caused by soil moisture deficits, leading to reduced water use efficiency and lower yields, which threaten food security and farmer’s livelihood. The use of microbial inoculants like Plant Growth Promoting Rhizobacteria and Arbuscular Mycorrhizal Fungi could serve as a tool to improve crop tolerance to water stress. This study was set to determine the influence of microbial inoculants on Water Use Efficiency (WUE) and yield in a watermelon in rain-fed cropping. The study was laid out in a Randomized Complete Block Design (RCBD), with four factorial treatments; PGPR, AMF, PGPR+AMF and a Control, where no amendments were added. The experiment was conducted for two consecutive seasons (Aug-Dec/2022 and Marc-Jul/2023). Application of PGPR significantly (P<0.001) increased WUE compared to control. Also AMF significantly increased WUE. However, watermelon crops treated with combined (AMF& PGPR), recorded the highest mean WUE compared with plots treated with rhizobacteria and mycorrhizal fungi only. There are significant differences in the interactions between the season, soil moisture, WUE and PGPR treatments on yield of watermelon crop under rain fed conditions. However, watermelon crop plots treated with PGPR only, demonstrated the highest significant increase on watermelon mean yield compared to control, and plots treated with AMF only and combined (AMF+PGPR). For water use efficiency farmers are recommended to use a combined application of (AMF+PGPR.). Because their application produced the highest mean water use efficiency compared with watermelon plots treated with AMF and PGPR only. For yield, farmers are recommended to use PGPR inoculants at 10kgs per hectare. Because its treatment produced the highest mean yield of watermelon (fruit weight (tons/ha) compared with watermelon plots treated with AMF only and combined (AMF+PGPR). Further research should focus on investigating dosage rates of AMF which is most effective in rain fed watermelon conditions in Uganda.
Potential of using indigenous microorganisms for decomposing coffee and rice crop waste into bio-fertilizer
(Kyambogo University (Unpublised work), 2025-11) Akampa, Caroline
Agricultural waste contributes approximately 140 billion tonnes to global waste annually, much of it rich in nutrients originally absorbed from the soil. Managing this waste sustainably while replenishing soil fertility is critical for long-term agricultural productivity. In Uganda, coffee and rice husks are abundant crop residues but decompose slowly due to their high lignin and cellulose content. This study aimed to evaluate the effectiveness of Indigenous Microorganisms (IMOs) in accelerating the decomposition of coffee and rice husks and improving compost quality. The experiment was conducted at Kyambogo University Farm, Central Uganda, using a Completely Randomized Design (CRD) with four treatment combinations replicated five times. The treatments were; i i) Coffee husks + goat manure (CH+GM), ii ii) Coffee husks + goat manure + IMOs (CH+GM+IMO), iii iii) Rice husks + goat manure (RH+GM), and iv iv) Rice husks + goat manure + IMOs (RH+GM+IMO). Each composting pit contained 25 kg of material mixed at a ratio of 1:0.5 (husks to goat manure) on a dry-weight basis. A culture of beneficial anaerobic and aerobic microorganisms was prepared from leaf litter collected from a forested area adjacent to Kyambogo University Farm so as to ensure the microbes originated from a natural (indigenous) soil ecosystem conducive for microbial diversity and proliferation. Treatments with IMOs received 1 liter of IMO solution, while controls received plain water. Data on temperature, pH, moisture content, organic matter, macronutrients (N, P, K, Ca, Mg), micronutrients, and C/N ratio were collected over a 12-week composting period.

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