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Soil nematode communities as influenced by fertility management practices, growth and yield of common beans (Var. Mwitemania) in Tharaka Nithi, Kenya
(Chuka University, 2025-10) Muraki, Margaret Wairimu
Common bean yield is relatively low due to soil infertility, diseases, and pests such as plant-parasitic nematodes (PPNs), as well as unfavorable climatic conditions, among other factors. PPNs have been reported to cause yield losses of up to 60% while free living nematodes (FLN) contribute positively to soil health. The study's general objective was to evaluate the effect of fertility management practices on soil nematode communities and the yield of common beans in Tharaka Nithi County. The treatments included NPK (23.23.0), Trichoderma harzianum (45g/20 litres), farmyard manure (10 ton/ha), and a control (with no amendment), which were laid out in a randomized complete block design (RCBD) and replicated three times. Soil samples were taken from the field before bean sowing, at flowering, and after harvesting common beans in each trial. Nematodes were extracted from 200ml of soil and 5g of roots using Modified Baermann technique. Data were collected on bean growth every two weeks and on yield components. Meanwhile, nematode numbers were counted,and species diversity and evenness were calculated per plot. The data values obtained were subjected to analysis of variance using R version 4.5.0, and significant means were separated using the Least Significant Difference Test at α = 0.05. Results
showed that in both trials, Farmyard manure increased FLN in soil (941) and showed a significant difference (p<0.05) from all other treatments and compared to the control, which reduced FLN in soil (110). The control treatment had the highest population of PPNs in soil (773) and showed a significant difference (p < 0.05) from the other treatments, while Trichoderma harzianum reduced the PPN population (123) in the soil. Control treatment increased Shannon diversity (1.68), Simpson’s diversity (0.78), and evenness (0.9) of PPNs as compared to Trichoderma harzianum, which reduced Shannon diversity (1.03), Simpson’s diversity (0.49), and evenness (0.85). Trichoderma harzianum increased the Shannon diversity (1.35), Simpson’s diversity (0.7), and evenness (0.84) of FLN compared to the control, which reduced the Shannon diversity (0.85), Simpson’s diversity (0.54), and evenness (0.77). The NPK (23.23.0) treatment had the highest growth response which recorded the highest values across four intervals of data collection on height (85.80 cm), number of leaves (72.5), branches (23.54), pods (25.34) seeds (169.39), biomass (1211.72 kg/ha), and grain yield (4592.60 kg/ha), and showed significant difference (p<0.05) from other treatments while control had the reduced growth response of height (39.08 cm),
number of leaves(19.25), branches (5.75), pods (5.87) seeds (32.67), biomass (193.24 kg/ha), and grain yield (586.42 kg/ha). Trichoderma harzianum had the highest number of nodules (50.5) and showed a significant difference from other treatments,while NPK (23.23.0) had the least (2.9). The NPK treatment increased PPNs in roots (46) and showed a significant difference (p < 0.05) from other treatments compared to Trichoderma harzianum, which reduced PPNs (2.5) in roots. Farmyard manure and Trichoderma harzianum emerged as promising strategies for managing PPNs while promoting beneficial nematodes to enhance common bean yields and soil health. Continuous assessment of nematode communities over multiple growing seasons is crucial for understanding the long-term effects of various soil amendments on diversity and crop productivity
Ab initio defect engineering and green synthesis of ca-mg Codoped titania and zirconia for photocatalytic Applications
(Chuka University, 2025-10) Mbae, Jane Kathure
The growing demand for long-term solutions to environmental pollution and energy concerns has sparked interest in photocatalysts that work efficiently in visible light. In particular, TiO2 and ZrO2 photocatalysts have shown great potential in photocatalytic degradation and disinfection applications. However, traditional TiO2 and ZrO2photocatalysts feature metastable phases that are better photocatalysts, large bandgaps, low solar energy utilization, and rapid charge carrier recombination, limiting their usefulness. This study addresses these limitations by investigating Ca-Mg codoping as a defect engineering strategy for improving the photocatalytic performance of TiO2 and ZrO2. The primary objectives were to determine the phase stability of Ca-Mg codoped TiO2 and ZrO2 polymorphs using Density Functional Theory (DFT), to evaluate the effects of oxygen vacancies on their electronic structures, to establish optimal dopant
concentrations for visible light activation, to green synthesize and characterize the predicted visible-active materials, to assess photocatalytic activity via Rhodamine B degradation under visible light and to evaluate antibacterial performance against E. coli and S. aureus. In this study, a combined ab initio and experimental approach was undertaken. Density Functional Theory (DFT) method was used to simulate the codoped polymorphs at different doping levels. Optimal codoped systems found suitable for visible light photocatalysis were green synthesized and characterized using XRD, ICP-MS and UV-VIS spectroscopy. The photocatalytic properties of the synthesized materials were evaluated by degradation of Rhodamine B (RhB) under
visible light and the disinfection capability was tested against Escherichia coli and Staphylococcus aureus bacteria strains. The results yielded reasonable agreement between experimental and theoretical results, as well as a better understanding of the system. DFT results showed that Ca-Mg codoping stabilizes the anatase phase in TiO2 by increasing the c/a ratio and induces tetragonalization in monoclinic ZrO2 through lattice distortions and oxygen vacancy formation. Defective oxygen vacancy Localized mid-gap states were discovered in Ca-Mg codoped TiO2 and ZrO2 systems. These states served as trapping sites for the photogenerated charge carriers and significantly decreased the energy band, improving visible light absorption. Experimentally, the
green synthesized codoped materials revealed smaller crystallite sizes (5.567 nm for TiO2 and 8.647 nm for ZrO2) and narrower bandgaps (1.92 eV and 2.4 eV, for TiO2 and ZrO2 respectively). Codoped TiO2 degraded 99.3% of Rhodamine B in 120 minutes and completely inactivated S. aureus under visible light in 60 minutes. RhB degradation % for 5 cycles of codoped TiO2 and ZrO2 nanoparticles have remarkable stability and reusability, which is the key reason for their widespread use in photocatalytic degradation of dyes. Based on these findings, Ca-Mg codoping is recommended as an economical, non-toxic and effective strategy for tuning the structural and electronic properties of TiO2 and ZrO2 to enhance visible-light photocatalysis. Future work should
focus on advancing the green synthesis technique and testing against a larger spectrum of contaminants and microbial strains to further establish its environmental application.
Effect of strategic innovations on the performance of savings and credit cooperative societies in Nairobi city county, Kenya
(Chuka University, 2025-10) Bundi, Moses Kimanthi
Strategic innovation is crucial for long-term success. Savings and Credit Cooperatives (SACCOs) in Kenya are instrumental in Gross domestic product (GDP) growth and uplifting the livelihoods of the people through job creation, poverty eradication by enhancing financial inclusion. Despite having a huge potential for growth, SACCOs in Nairobi City County have witnessed a decline in performance. While most of the SACCOs in Nairobi City County have started adopting various innovations, it is apparent from the performance that they are yet to harness well on these innovation strategies to improve their performance. Strategic innovation is a strategic management tool that can influence organizational performance, enhance competitiveness, adaptability and long-term sustainability. Anchored in the strategic management perspective, this study examined the effect of strategic innovations on performance of SACCOs in Nairobi City County. The specific objectives were to examine the effect of product innovation, process innovation and marketing innovation on performance and the moderating effect of SACCO size on the relationship between strategic innovation and performance. This study was anchored on Schumpeter theory of innovation, dynamic capability theory and resource based view. Descriptive research design was adopted with a population of 177 SACCOs in Nairobi City County. The study adopted a census technique and the respondents were 177 chief executive officers or their equivalent in the SACCOs. Data was collected using a closed-ended questionnaire and a data collection sheet. Data was analyzed using descriptive and inferential statistics and with the aid of Statistical Package of Social Sciences version 28.0. Cronbach’s alpha was used to test reliability. Construct validity was tested using regression analysis. The content validity was done through research supervisors who checked if the research instrument captures all the relevant aspects to answer the research questions. The pilot study involved 18 respondents from 18 SACCOs in Kiambu County which constitute ten percent of the targeted chief executive officers. Simple and multiple regression analysis was done to establish the relationship between variables. Correlation analysis was used to test the strength of the relationship between variables. Data was presented using tables and figures. T-test and F- test was used to test hypothesis at 5% significance level. The results of the study indicate that product innovation was statistically insignificant (β=-0.051, P-value=0.541>0.05). The results of the study indicate that process innovation and marketing innovation were statistically significant (β=0.634, P-value=0.000<0.05, β=0.548, P-value=0.000<0.05) respectively. The results of the study indicate that the interaction effect between strategic innovation and SACCO size was statistically significant (β=0.279, Pvalue=0.016<0.05). Savings and Credit Cooperatives are encouraged to adopt modern technologies and efficient systems that streamline operations, reduce costs, and improve service delivery. SACCOs should strengthen marketing efforts by embracing digital platforms, targeted campaigns, and member engagement strategies to increase visibility and attract new members. SACCO managers should continuously improve internal operations by adopting technology-driven process innovations such as automated loan processing systems, mobile banking applications, and real-time data management tools. Furthermore, policy makers should develop and implement flexible guidelines that support digital transformation, such as e-banking, automated loan systems, and electronic record management, without imposing excessive compliance burdens.
Selected determinants of individual demand for Education and student participation in public day Secondary schools, Mwala sub-county, Kenya
(Chuka University, 2025-10) Mbithi Annabel Wanza
Student participation in classroom and co-curricular activities is crucial for improving educational outcomes. This participation is influenced by individual demand for education, which includes parental income, the direct and indirect costs of schooling, and students' employment expectations. While these factors are acknowledged as important, empirical evidence regarding how individual demand for education influences student involvement, especially in rural areas like Mwala Sub-County, Machakos County, is limited. This thesis evaluated the determinants of individual demand for education and student participation in classroom and co-curricular activities within public day secondary schools in Mwala Sub-County. The research adopted a descriptive survey research design and was anchored under Human Capital and Expectancy-Value theories. The target population comprised 1,879 Form Three students, 117 class teachers, and 39 school principals from 39 public day secondary schools. The data was collected from a sample of 320 students, 36 class teachers, and 12 school principals from 12 randomly selected schools. Data were collected through structured questionnaires for students and class teachers and interview guides for principals. A pilot was done to establish the feasibility of the study. Validity was ensured through consultation with the experts of the Department of Education. Reliability was estimated using Cronbach's alpha, and the included values (ranging from 0.768 to 0.979) were obtained, surpassing the threshold of 0.7. Hence, the instruments were reliable for data collection. Data analysis utilized descriptive statistics, Pearson correlation, and ordered logistic regression using SPSS version 30. Interview data were thematically analyzed. The findings revealed that 75% of students took notes, 74.4% participated in sports, and only 38.4% participated in academic competitions, suggesting the need for greater encouragement in academic-focused activities. The findings revealed a significant positive correlation between parents' disposable income and student participation in classroom and co-curricular activities (r = 0.215, p = 0.000 for students; r = 0.531, p = 0.001 for class teachers). The ordered logistic regression further confirmed that lower disposable income limits student participation (β = 0.339, p = 0.008 for students; β = 2.702, p = 0.002 for class teachers). The cost of education was also a major issue, with 34.4% of students missing school due to unaffordable fees. Similarly, the cost of education was found to limit participation, with significant correlations (r = 0.415, p = 0.000 for students; r = 0.790, p = 0.000 for class teachers) and ordered logistic regression results (β = 0.357, p = 0.003 for students; β = 5.950, p = 0.000 for class teachers). Employment expectations strongly motivated participation, with students having higher career aspirations showing more participation. Employment expectations showed a strong positive correlation with participation (r = 0.689, p = 0.000 for students; r = 0.842, p = 0.000 for class teachers), with significant coefficients (β = 1.614, p = 0.000 for students; β = 8.112, p = 0.000 for class teachers), highlighting career aspirations as a key factor motivating par. These findings emphasize that career expectations are the most critical factor influencing student participation. The study concluded that parental disposable income, the cost of education, and students' career expectations significantly influence their participation in both classroom and co-curricular activities. The research recommends that parents, class teachers, principals, and policymakers from the Ministry of Education take targeted actions to enhance student participation in both academic and co-curricular activities.
Effect of integrated cattle manure and phosphatic fertilizer application on orange fleshed sweet potato yield and quality
(Chuka University, 2026-10) Mwangi, Stephen Kahora
Sweet potato (Ipomoea batatas L.) is a highly nutritious and a resilient crop with significant potential to enhance food security and reduce poverty in Kenya. However, its production has declined in recent years due to poor agronomic practices, particularly inadequate soil fertility management. Phosphorus deficiency remains a major constraint, as most farmers rarely apply phosphatic fertilizers, and research on optimal combinations of fertilizer and manure application to maximize yield and quality is limited. The objective of this study was to evaluate the effects of combined application of different levels of cattle manure and phosphorus (P) fertilizer on the yield and quality of orange-fleshed sweet potato, variety Vita. The study was conducted at two sites, Wambugu Agricultural Training Farm in Nyeri County and Kibirigwi Irrigation Scheme in Kirinyaga County. A 3 × 3 factorial experiment laid out in a Randomized Complete Block Design with three replications was used. The treatments were; cattle manure at 0 t/ha, 1.5 t/ha, and 2.5 t/ha, and phosphorus-based inorganic fertilizer (TSP) at 0 kg/ha, 50 kg/ha, and 75 kg/ha. Treatments were applied at planting. Data were collected on vine length, number of branches per plant, number of leaves, days to 70% maturity, tuber diameter, length, weight, and proximate analyses for quality determinants including dry matter content, vitamin A, and ash content. The results revealed significant differences (p < 0.05) in vine length, vine girth, number of branches, and leaf area index across treatments. Growth parameters improved progressively with increasing manure and TSP application, with the combination of 2.5 t/ha manure + 75 kg/ha TSP (T3S3) consistently producing the most vigorous plants. Vine girth under T3S3 reached 4.823 cm by 112 DAS, significantly higher than 2.507 cm under the control (T1S1). In terms of yield performance, root yields ranged from 1.07–1.09 t/ha in the control to 3.00–3.10 t/ha under T3S3, representing nearly a threefold increase. Intermediate treatments, such as 1.5 t/ha manure + 50 kg/ha TSP, also showed substantial yield improvement, underscoring the synergistic effect between organic and inorganic nutrient sources. Across sites, yields were consistently higher under integrated treatments, with greater responsiveness observed at Kibirigwi (nutrient-deficient soils) compared to Wambugu (moderately fertile soils). Nutritional analysis indicated that integrated treatments enhanced root quality, with significant increases in β-carotene, vitamin C, and crude protein compared to the control. The highest β-carotene content (10.03 mg/100 g) was recorded under T3S3, compared to 3.47 mg/100 g under the control. Similarly, T3S3 produced the highest dry matter and vitamin C concentrations, demonstrating that nutrient supplementation not only enhances yield but also improves the nutritional value of OFSP, thereby contributing to food and nutrition security. These findings confirm that integrated nutrient management enhances both agronomic and economic outcomes. Integrated application of cattle manure and TSP significantly improved sweet potato growth, yield and nutritional quality. The combination of 2.5 t/ha manure and 75 kg/ha TSP (T3S3) proved most effective across both sites, validating the superiority of integrated over sole nutrient applications. Farmers are encouraged to adopt integrated use of cattle manure and TSP for sustainable sweet potato production. Extension programs should promote awareness of the agronomic, nutritional, and economic benefits of integrated nutrient management. Future studies should assess long-term impacts on soil health, as well as adaptability of the approach across diverse agro-ecological zones to refine site-specific recommendations