Master Theses: Department of Water and Agricultural Resource Management

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Resilience of Nitisols And Ferralsols To Erosion As Influenced By Levels Of Soil Organic Carbon In Tharaka-Nithi County, Kenya
(UoEm, 2025-09) Mercy Kangai Rugendo
Declining soil fertility resulting from nutrient losses due to erosion is a major constraint to agricultural productivity and food security among smallholder farmers in Sub-Saharan Africa (SSA). Managing soil organic carbon (SOC) levels is a promising strategy to mitigate erosion since SOC directly influences soil structure, water retention, infiltration, and nutrient cycling. This study aimed to evaluate the effect of different SOC levels under varying simulated rainfall intensities on water retention, infiltration rates, runoff volume, sediment yield, and nutrient losses in Nitisols and Ferralsols soils found in Tharaka-Nithi County, Kenya. The research was conducted in farmers’ fields located in Chuka and Tharaka-South sub-counties, representing the Nitisols and Ferralsols, respectively. Soil samples were analyzed and categorized into low (1.0 to 1.5), moderate (1.6 to 2.5) and adequate SOC (above 2.5%) content. The experiment was laid out in a split plot design arranged in randomized complete block design, where SOC levels were main plots and rainfall intensities were the sub-plots. Rainfall intensities of 80, 100, and 120 mm/hr were simulated on 1 m² experimental plots fenced with corrugated iron sheets to accurately collect runoff and sediments. Key parameters measured included runoff volume, sediment yield, soil bulk density, hydraulic conductivity, and water retention. Runoff and sediment samples were analyzed for primary and secondary macronutrient concentrations using standardized laboratory methods. The collected data were subjected to analysis of variance (ANOVA) followed by Tukey’s Honest Significant Difference (HSD) test. Pearson correlation analysis was performed to examine the relationship between the different variables of interest. The findings revealed that higher SOC levels significantly reduced runoff volumes and sediment losses across both soil types and all rainfall intensities. Specifically, soils with high SOC exhibited a 40–55% decrease in runoff and a 35–50% reduction in sediment yield compared to low SOC soils. Runoff and sediment volumes were also significantly higher in Ferralsols than in Nitisols. Water retention and infiltration rates improved markedly with increased SOC, indicating enhanced soil physical properties. Nutrient losses, particularly nitrogen and phosphorus, were lower in plots with higher SOC, demonstrating improved nutrient retention capacity. Pearson correlation analysis confirmed a strong positive (r = 0.85) relationship between runoff volume and sediment loss, underscoring the importance of reducing runoff by improving infiltration. The study concluded that enhancing SOC levels is essential in improving soil resilience against erosion, enhancing water availability, and conserving nutrients in Nitisols and Ferralsols. Sustainable agricultural practices such as organic amendments, that build SOC should be promoted to improve soil health and agricultural productivity. These results make a clear practical case: prioritize SOC-building practices (residue retention, organic amendments, cover crops, reduced tillage) to reduce runoff, sediment, and nutrient losses from Nitisols and Ferralsols.
Agro-Morphological, Nutritional and Phytochemical Characterization of Bambara Groundnut Landraces Under Varying Agroecological Conditions in Embu County, Kenya
(UoEm, 2024-07) Mercy Chelangat
Bambara groundnut is an underused leguminous crop in the Fabaceae family that originated from West Africa. Agro-morphological and nutritional diversity studies to determine Bambara groundnut landraces with superior end-user preferred traits are limited. The objective of this study was to determine the agro-morphology, nutritional, and phytochemical profiles of Bambara groundnut landraces grown in Kenya. For two cropping seasons, field experiments were conducted in Embu West (Kangaru), Mbeere North (Ishiara), and Mbeere South (Kiamuringa) sub-counties, in Embu County. Three replicates of the field tests were set up using a Randomized Complete Block Design (RCBD). All the agro-morphological data were collected based on International Plant Genetic Resource Institute (IPGRI) descriptors for Bambara groundnuts. Five Bambara groundnut plants were selected randomly from each plot and tagged for data collection. Both qualitative and quantitative data were organized in a matrix and subjected to cluster and Principal Component Analysis (PCA) to select landraces with superior agro-morphological traits. Using XLSTAT software 2023, analysis of variance (ANOVA) was performed on quantitative data, and the means were separated using Tukey's Honest Significant Difference (HSD) at a 95% confidence level. Pearson correlation was conducted to assess the strength of linear relationships between agro-morphological traits. Phytochemical, nutritional, and compositional analyses were conducted using standard procedures, and the resulting data were subjected to ANOVA, cluster analysis, and PCA. Pearson correlation analysis was also done to determine how the nutritional and phytochemical variables related to one another. Higher yields were obtained in the first season compared to the second in all locations, and there were significant location effects for all quantitative traits. A combined analysis of variance revealed significant differences (P<0.05) in all agro-morphological variables evaluated except for days to first flowering, days to 50% flowering, and plant height. The yields ranged from 0.84–5.01 t ha⁻¹ (Kiamuringa), 0.69–3.14 t ha⁻¹ (Kangaru), and 0.60–2.44 t ha⁻¹ (Ishiara). Yield correlated positively and significantly (P<0.05) with days to first flowering, weight of 100 seeds, days to 50% flowering, and number of seeds per plant. The landraces BS-107, LU-122, LU-121, BS-134, and BS-144 were among the high-yielding landraces identified and can be adopted for cultivation. In the pooled data for both seasons, there were significant variations (P<0.05) in every phytochemical and nutritive trait. The total ash ranged from 3.17 to 4.69%; moisture content from 3.47 to 6.24%; fats from 4.56 to 7.02%; and crude protein from 21.18 to 26.00%. Zinc ranged from 0.06 to 0.42 mg/100g; iron levels from 4.07 to 5.13 mg/100g; potassium from 819.34 to 1,133.80 mg/100g; and sodium from 25.14 to 129.66 mg/100g. The saponin levels ranged from 0.82 to 1.06 mg/100g; tannin from 0.01 to 0.04 mg/g; flavonoids from 4.07 to 8.45 mg/100g; and alkaloids from 0.01 to 0.12 mg/100g. The landraces with high nutritional value, such as BG-125, BS-148, and BS-145, among others, are recommended for adoption by farmers, while those with high levels of phytochemicals, such as BS-104 for flavonoids and MU-137 for saponins, are recommended for exploitation by pharmaceutical and nutraceutical industries. The nutritional value of landraces BS-114, LU-123, and KS-108 should be enhanced by lowering their sodium content levels.
Assessment of fodder conservation in smallholder dairy farming systems in highland and midlands of eastern Kenya
(UoEm, 2025-06-03) Kogo, Thomas Kipchoge
GENERAL ABSTRACT The dairy industry is important for its contribution to the living standard of people, industries, foreign exchange and 4% of the total GDP in Kenya. Productivity of 7.8 liters/cow/day is low and attributed to poor feeding and contribution to high emission of greenhouse gases (GHGs). Fodder scarcity poses a challenge to the achievement of high productivity, while mitigation of fodder scarcity through fodder conservation remains low. Despite common challenges, farms perform differently, in different farm locations with some farms, also called positive deviants (PDs) conserving adequate fodder. In the highlands and midlands of eastern Kenya, information on fodder conservation among smallholder dairy farming systems is limited. The adoption levels and the intensity of fodder conservation technologies including silage and hay, factors affecting the adoption and use of such technologies in (peri-) urban locations and strategies used by PDs in fodder conservation are unknown. Therefore, the study sought to assess fodder conservation technologies among smallholder dairy farming systems in the highlands and midlands of Tharaka-Nithi County, Kenya. Specifically: to determine factors affecting the adoption intensity of fodder conservation. To determine factors of fodder conservation technologies adoption in urban and peri-urban areas. To determine strategies that distinguish PDs from peers (non-PDs) in fodder conservation. A cross-sectional survey was conducted on smallholder dairy farms producing and conserving fodder in Tharaka Nithi County. Multistage sampling procedures were used: purposive sampling of the Sub- counties and locations, random selection of villages and proportional selection of 242 farms through snowball chain referral. The questionnaire was used to collect information, which included: household socio-demographics, husbandry practices, farm characteristics and fodder conservation characteristics. Two towns were chosen purposively to represent urban locations i.e. Chuka (UL, n=68) and peri-urban locations Chogoria (PUL, n=93) in Chuka and Maara Sub-Counties respectively (Total n=161), due to the relatively high number of urban dwellers. Additionally, the PDs (n=24) conserved fodder adequate to last the dry season and had a milk yield of ≥15 kg/cow/day. While non-PDs (n=97) do not qualify for both criterion as farms qualifying for one criteria were discarded. Multiple regression analysis was applied to explain the quantity of fodder conserved. The Multivariate Regression (MVR) model was used to identify and estimate simultaneously the determinants of fodder conservation technologies adoption. Logit regression was used to examine variables that influence the probability of PDs. The study found that most farms were headed by older males who had basic education. Fodder was scarce during the dry season in most farms. Fodder conserved included; silage was conserved in the least number of farms only 26%, but the highest in the quantity of fodder conserved (13 tons); hay was conserved in 40% of the farms, but the quantity conserved was the least (2 tons); crop residue storage was the major conserved fodder by 85% of the farms and the quantity conserved was 5 tons. Quantities of fodder conserved were affected by land size, herd size, duration planned to use conserved fodder, main fodder source during scarcity and the fodder conservation technologies used (silage and hay). Quantities of silage and hay conserved were higher in urban location (UL) than in peri- urban locations (PUL) farms. Crop residue storage was conserved more in non-PD farms, especially in PUL farms. Fodder conserved in UL and PUL was influenced by farm location, land size, herd size, total milk yield per farm, sex, source of fodder during feed scarcity, extension services, period the current stock is expected to last, use of concentrate feeds and breed kept. Access to extension services, milk yield, land size, land under xivfodder, period to use conserved fodder, total herd size, and different combinations of fodder conservation technologies differ between PDs and non-PDs. PDs in fodder conservation are favored by a high level of education, access to extension services, large land, herd size and high milk yield. The study shows knowledge production resources and technology used as important in fodder conservation. Recommended mitigation measures target more education on fodder conservation technologies as well as increasing the adoption of improved fodder production. Knowledge advancement of farmers and policymakers through education and extension increases milk production. Therefore, policymakers can focus on creating enabling policies that promote the adoption of improved technologies as used by PDs to support fodder production and conservation to improve productivity and inform the direction of future research.
Soil carbon stocks and greenhouse gas fluxes quantification in selected smallholder farmers' land utilization types of Siaya county, Kenya
(Esphorn Kibet, 2022-09) Kibet, Esphorn
The up-surging population in sub-Saharan Africa (SSA) has led to the conversion of forests to agricultural land leading to greenhouse gas (GHG) emissions. The resilient land utilization types are key in soil carbon sequestration. There is a vast data gap for the National and regional greenhouse gas (GHG) budget from different smallholders’ land utilization types in Kenya and sub-Saharan Africa (SSA). This study aimed to quantify carbon stock and greenhouse gas fluxes from different land utilization types (LUT) in Siaya. The LUTs considered in the study were agroforestry M (agroforestry with Markhamia lutea), sole sorghum, agroforestry L (agroforestry with Leucaena leucocephalaI), sole maize, and grazing land replicated thrice. Soil samples were collected at a depth of 0-5, 5-10, 10-20, and 20-30cm from different LUTs to determine soil bulk density, organic carbon (SOC) concentration, and carbon stock. PROC ANOVA was used to determine the significant difference in soil bulk density, SOC %, SOC stock. Additionally, GHG data were subjected to analysis of variance (ANOVA) using SAS 9.4 software. Before analysis, the normality of soil GHG fluxes was tested using the Shapiro-Wilk test. DeNitrification-DeComposition (DNDC) model was also used to simulate GHG gases. Soil bulk density varied significantly (p<0.05) across the LUTs and soil depths with a range of 1.30 and 1.60gcm-3 under Agrofestry M and grazing land, respectively, at 0-5cm depth. A significant difference (p<0.0001) in SOC concentration was observed with high SOC concentration under Agroforestry M of 30.14gCkg-1 at 0-5cm depth than all the other treatments and low SOC (8.4g Ckg-1) in sole maize. Soil organic carbon stocks significantly (p<0.0001) varied across LUTs and depths. There was high carbon stock in agroforestry M (19622 kg C ha-1) and grazing land (20069.7kgCha-1) at 0-5 cm. Soil GHG fluxes significantly varied across the LUTs methane p<0.05, Carbon diode p=0.05, and nitrous oxide p=0.05. The cumulative methane fluxes ranged from -0.35 kg CH4-C ha-1 in grazing land highest -1.05 kg CH4-C ha-1 sole maize. Low soil CO2 emissions under sole maize, 6510 kg CO2-C ha-1, and the highest under grazing land were observed, 14401 kg CO2-C ha-1. The results showed the lowest soil N2O fluxes under grazing land, 0.69 kg N2O-Nha-1, and the highest under agroforestry L 2.48 kg N2O-N ha-1. The model showed a high degree of fit in simulating daily soil temperature, soil moisture, and soil N2O emissions. The model depicted good results during simulation of soil moisture; root mean square error (RMSE) <5, 2% < normalized root means square error (nRMSE) <15.54%, 0.86< modelling efficiency (NSE) (NSE) <0.99, 0.03< coefficient of determination (R2) <0.97 and (index of agreement) d < 0.99. Daily soil temperature; 0.08
Characterisation of smallholder farming systems and greenhouse gas emissions simulation from maize cropping system in tharaka-nithi county, kenya
(COLLINS MUIMI MUSAFIRI, 2020-08) MUSAFIRI, COLLINS MUIMI
The influence of soil fertility management technologies on crop production has widely been researched in Tharaka-Nithi County. However, data on their contribution towards national greenhouse gas budget is scanty. This study aimed at characterising smallholder farming systems and simulating greenhouse gas emissions, maize yields, yield scaled nitrous oxide (N2O) emissions and N2O emission factors from different soil fertility management technologies in Tharaka-Nithi County. Three hundred households were interviewed to obtain data for farming systems characterisation and evaluation of socio-economic factors influencing the diversity of farm typologies. Interview schedules were administered using open data kit collect mobile App. Multivariate analysis was done to characterise smallholder farming systems. To evaluate socio-economic factors influencing farm diversity, Chi-square, t-test, and multinomial regression analysis were carried out using the Statistical Package for Social Sciences (SPSS version 23). For calibration and validation of the DeNitrification DeComposition (DNDC) model, a one-year soil greenhouse gas quantification experiment data were used. The data were obtained from a field experiment conducted in Kigogo primary school. It was laid out in randomised complete block design under four soil fertility treatments as control (no external inputs), inorganic fertiliser (NP, 23.23, 120 kg N ha-1 yr-1), animal manure (goat manure, 120 kg N ha-1 yr-1) and animal manure + inorganic fertiliser (120 kg N ha-1 yr-1) replicated thrice. Climate, soil properties, N2O fluxes, maize yields and farm management data were used. The model was evaluated using modelling efficiency, mean error, coefficient of determination, mean absolute error, and root mean square error (RMSE). The experimental data were subjected to Analysis of Variance in SAS 9.4 software and mean separation done using least significance difference at p = 0.05. The results showed six farm types: Type 1, comprising cash crop and hybrid cattle farmers; Type 2, involving food crop farmers; Type 3, composed of coffee-maize farmers; Type 4, consisting of millet-livestock farmers; Type 5, comprising highly diversified farmers, and Type 6, had tobacco farmers. Land size, total tropical livestock unit, the proportion of land and amount of nitrogen applied to different cropping systems were significant in the construction of farm typologies. The DNDC model was fair in simulating daily N2O fluxes (54% ≤ normalized RMSE (nRMSE) ≤ 68% and 0.26 ≤ modelling efficiency (MEi) ≤ 0.49) and good to excellent performance in simulating cumulative annual soil N2O fluxes (6.16 ≤ nRMSE ≤ 12.86 and 0.63 ≤ MEi ≤ 0.86) across soil fertility treatments. The cumulative observed and simulated annual soil N2O fluxes ranged between 0.21±0.01 and 0.38±0.02 kg N2O-N ha-1 yr-1 and 0.20 kg N2O-N ha-1 yr-1 (control) to 0.38 (fertiliser) kg N2O-N ha-1 yr-1. The simulated N2O yield scaled emissions, and emission factors ranged from 0.022 to 0.029 g N Kg -1 grain yield and 0.03 % to 0.14% under manure and fertiliser treatments, respectively. Based on the low observed and simulated emission factors, using the Intergovernmental Panel on Climate Change (IPCC) Tier 1 default factor of 1% overestimates agricultural soils GHG emissions in the Central Highlands of Kenya. Manure and fertiliser combination should be promoted to enhance the three pillars of climate-smart-agriculture (CSA) as food security, climate change mitigation and adaptation.
Effect of Tillage Methods and Nutrient Application Levels on Soil Properties and Soghum and Greengram Yields in Siakago, Embu County, Kenya
(LILY GICUKU NJIRU, 2024-08) Njiru, Lily Gicuku
Declining soil fertility is a significant constraint to sorghum and green gram yields for smallholder farmers in semi-arid regions of Kenya. This research was carried out in Siakago, Embu County, Kenya, with the aim of assessing the efficacy of different tillage methods and inorganic and organic fertilizers for sorghum and green gram production. The research was performed for four consecutive seasons from October 2018 to February 2021 at the Agricultural Technology Development Centre, Siakago in Mbeere North sub-County. In the study, there were a total of 24 different treatments using a randomized full block design with three replicates. The treatments comprised of two different types of tilling, namely conventional and tied ridges, three cropping systems (sole-green grams, sole-sorghum, and green grams + sorghum intercrops) and four soil fertility input regimes (no inputs), (60 kg DAP ha-1 ), (5.0 t ha-1 manure) and a combination of manure and inorganic fertilizer as (2.5 t ha-1 + 30 kg DAP ha-1 ). Soil properties, including organic carbon, nitrogen, phosphorus, potassium, calcium, magnesium, manganese, iron, zinc, and copper, were analyzed before and after the experiment. Crop parameters, such as days to 50% flowering, plant height, leaf chlorophyll content, biomass, and grain yields, were also measured. The treatment effects were analyzed using ANOVA, and a significance level of p ≤0.05 was used to differentiate the treatment means using post hoc Turkey’s HSD test. Differences in treatment means were analyzed using Fisher's test for the test with the least significant difference, which was performed at a significance level of p ≤ 0.05. The results showed that tied ridge tillage practice significantly increased exchangeable phosphorus and magnesium contents. The green gram cropping system registered higher but insignificant nutrient status compared to sole sorghum or sorghum-green gram cropping systems. Organic-based fertility inputs positively affected soil organic carbon, although these increases were not statistically significant. Soil inputs significantly influenced soil carbon concentrations, with the lowest values observed in the control treatment. The study found that sorghum supplied with full-rate inorganic fertilizer had greener leaves and produced 75% higher grain than in the control. The pure farmyard manure treatment produced 45% more grain compared to the control. Tied ridges did not significantly increase yields p ≤ 0.05. Similar trends were observed in green grams. This research emphasizes the significance of applying soil conservation techniques, such as tied-ridging, in conjunction with organic input applications, to improve the availability of multiple nutrients for better crop performance and human nutrition in dryland farming systems.
Quantification of greenhouse gas fluxes from selected cropping systems under on farm conditions in tharaka-nithi, kenya
(Ezekiel Lemarpe Shaankua, 2024-03)
The smallholder cropping systems have an adverse effect on greenhouse gas (GHG) emissions to the ecosystems due to varied contribution to the GHG budgets. Further, the uncertainty on the contribution of an individual anthropogenic trace gas (CH4, CO2, and N2O) to the GHG emissions is rising due to disproportionate concentration contribution. The general objective was to quantify GHG emissions from selected cropping systems and asses N2O dynamics. The specific objectives were to: i) quantify greenhouse gas fluxes (CH4, CO2 and N2O) from selected cropping systems in Tharaka-Nithi County ii) evaluate N2O emissions from smallholders’ cropping systems, and ii) determine the environmental factors, climatic conditions, farm management practices, and soil properties that influence N2O dynamics. The field experiment was undertaken under on-farm conditions, fully managed by farmers for one year (two cropping seasons). For the field experiment, five cropping systems were evaluated: i) sole maize, ii) maize intercropped with beans, iii) coffee, iv) banana, and iv) agroforestry. Gas was sampled using a static chamber arranged linearly in a randomized complete block design replicated thrice per cropping system. Gases were analyzed using gas chromatography (GC) fitted with a 63Ni-electron capture detector (ECD) for N2O and flame ionization detector (FID) for CH4 and CO2 using N as carrier gas. The cumulative soil GHG fluxes ranged from -1.34 kg CH4-N ha-1 yr-1 under agroforestry to -0.77 kg CH4-C ha-1 yr-1 under banana for CH4, 0.30 kg N2O-C ha-1 yr-1 to 1.23 kg N2O-C ha-1 yr-1 for N2O and 5949 kg CO2-C ha-1 yr-1 to 12954 kg CO2-C ha-1 yr-1 for CO2. The maize yields ranged from 0 to 3.38 Mg ha-1 . The nitrous oxide yields scaled emissions ranged from 0.10 to 0.26 g kg-1 maize and 0.68 to 1.30 g kg-1 beans. The review indicated that coffee, tea, maize, and vegetables emit N2O ranging from 1 to 1.9, 0.4 to 3.9, 0.1 to 4.26, and 48 to 113.4 kg N2O-N ha-1 yr-1 , respectively. Precipitation was the key driver of both CO2 and N2O emissions in the study area. The yieldscaled and N2O emissions factors ranged between 0.08 and 67 g N2O-N kg−1 and 0.01 and 4.1% across cropping systems. Soil characteristics, farm management practices, and climatic and environmental conditions are significant drivers that influence N2O emissions across SSA cropping systems. Smallholder farmers in Central Highland of Kenya also contribute to global GHG emissions through cropping systems. These results are within the previous GHG fluxes findings in SSA. Therefore, this forms the baseline for estimating GHG in the agroecosystems in Africa
Utilization of rainwater harvesting technologies among smallholder farmers in murang’a county,
(Francis Irungu Itemo, 2024-08) Francis Irungu,
Water is a critical resource in environmental sustainability, agricultural production as well as for improved livelihoods. Climate variability hinders crop and livestock production in Sub-Saharan African countries. Rainwater harvesting (RWH) is a climate smart agricultural practice to revert this. Rainwater harvesting has been practiced among smallholder farmers for centuries in many parts of the world. Recently, it has gained more attention due to the reported increasing water demand and the need for sustainable water management hence the research was conducted to evaluate the utilization of rainwater harvesting technologies (RWHTs) as a climate smart agricultural practice in Murang’a County, Kenya. Drawing on data from a cross sectional survey of 384 households, our research evaluated the adoption of RWHTs, intensity of crop and livestock enterprises adoption under RWHTs and the determinants for RWH among smallholder farmers in Murang’a County, Kenya. Multistage random sampling and proportionate to size technique was employed to sample farmers in three wards namely: Murarandia, Mugoiri and Wangu. The KOBO kit a phone application was used during data collection. To assess the adoption of RWHTs, descriptive statistics and analysis of variance (ANOVA) were applied. The results found that rooftop water harvesting technology (93a ± 22), infiltration pits (81a ± 21), furrows (68a ± 16), deep ploughing (67a ± 21), terraces (54a ± 14), mulching (51a ± 17), retention ditches (23a ± 18) and water pans (17a ± 5) water harvesting technologies had statitistical significant differences among smallholder farmers (P<0.05), while negarims, water bunds and dams water harvesting technologies were not statistically significant (P<0.05) adopted at a mean ± S.D of 11 ± 4, 6 ± 2 and, 1 ± 1 smallholder farmers, respectively. The findings exhibited that households that practiced livestock production including: dairy cattle farming, goat rearing, sheep farming, beef cattle rearing, pig production, and poultry farming, watered their livestock using rooftop harvested rainwater at a rate of 12%, 10%, 9%, 6%, 3% and 5%, respectively while, 1% practiced aquaculture. Multivariate probit model (MVP) analysis showed that crop enterprises adopted (macadamia, maize, coffee, tea, avocado, fodder, arrowroots, beans, bananas, mangoes and sweet potatoes) among household heads were key crop enterprises that influenced adoption of these RWHTs. The MVP model also pointed out that household head’s access to credit facilities, landownership, age, level of income, education level, gender, family size, source of income, membership to farmers’ groups and access to training services were statistical significant (P<0.05) thus, influenced RWH adoption. Membership to farmers group had merits including: support in farmers’ training, social ties, source of information and source of credit which were also key determinants to RWH adoption. The study recommends relevant stakeholders and policy makers to consider promotion or up scaling of RWHTs for crop and livestock enterprises among household heads in consideration of the determinants influencing adoption rate in Murang’a County.
Qualification of Greenhouse Gas Fluxes from Selected Cropping Systems under on Farm Conditions in Tharaka-Nithi, Kenya
(UoEm, 2024-03) Lamarpe Shaanuka, Ezekiel
The smallholder cropping systems have an adverse effect on greenhouse gas (GHG) emissions to the ecosystems due to varied contribution to the GHG budgets. Further, the uncertainty on the contribution of an individual anthropogenic trace gas (CH4, CO2, and N2O) to the GHG emissions is rising due to disproportionate concentration contribution. The general objective was to quantify GHG emissions from selected cropping systems and asses N2O dynamics. The specific objectives were to: i) quantify greenhouse gas fluxes (CH4, CO2 and N2O) from selected cropping systems in Tharaka-Nithi County ii) evaluate N2O emissions from smallholders’ cropping systems, and ii) determine the environmental factors, climatic conditions, farm management practices, and soil properties that influence N2O dynamics. The field experiment was undertaken under on-farm conditions, fully managed by farmers for one year (two cropping seasons). For the field experiment, five cropping systems were evaluated: i) sole maize, ii) maize intercropped with beans, iii) coffee, iv) banana, and iv) agroforestry. Gas was sampled using a static chamber arranged linearly in a randomized complete block design replicated thrice per cropping system. Gases were analyzed using gas chromatography (GC) fitted with a 63Ni-electron capture detector (ECD) for N2O and flame ionization detector (FID) for CH4 and CO2 using N as carrier gas. The cumulative soil GHG fluxes ranged from -1.34 kg CH4-N ha-1 yr-1 under agroforestry to -0.77 kg CH4-C ha-1 yr-1 under banana for CH4, 0.30 kg N2O-C ha-1 yr-1 to 1.23 kg N2O-C ha-1 yr-1 for N2O and 5949 kg CO2-C ha-1 yr-1 to 12954 kg CO2-C ha-1 yr-1 for CO2. The maize yields ranged from 0 to 3.38 Mg ha-1 . The nitrous oxide yields scaled emissions ranged from 0.10 to 0.26 g kg-1 maize and 0.68 to 1.30 g kg-1 beans. The review indicated that coffee, tea, maize, and vegetables emit N2O ranging from 1 to 1.9, 0.4 to 3.9, 0.1 to 4.26, and 48 to 113.4 kg N2O-N ha-1 yr-1 , respectively. Precipitation was the key driver of both CO2 and N2O emissions in the study area. The yield scaled and N2O emissions factors ranged between 0.08 and 67 g N2O-N kg−1 and 0.01 and 4.1% across cropping systems. Soil characteristics, farm management practices, and climatic and environmental conditions are significant drivers that influence N2O emissions across SSA cropping systems. Smallholder farmers in Central Highland of Kenya also contribute to global GHG emissions through cropping systems. These results are within the previous GHG fluxes findings in SSA. Therefore, this forms the baseline for estimating GHG in the agro-ecosystem in Africa.
Productivity and profitablity of selected cabbage varieties under varying drip schedules in Humic Nitisols of Embu County.2
(2022-08) Onkoba, Stephen Onyiego
The adverse effects of climate change and increasing human population have put pressure on scarce water resources used in crop production. This consequently threatens the food and nutritional security of the growing human population. Vegetables are short season crops that are sensitive to water deficits during growth, leading to low productivity, poor marketability and reduced household incomes. Use of controlled irrigation in production of vegetables is considered a sustainable route for enhancing input use and productivity. This study sought to evaluate the effects of crop variety and drip irrigation schedules on productivity and profitability of cabbage grown in humic nitisols in Embu County, Kenya. The study applied a split plot laid in Randomized Complete Block Design (RCBD) in which the drip irrigation schedules were allocated the main plot and crop varieties were allocated the sub-plot treatments. The test varieties investigated were Riana F1, Gloria F1 and Triperio F1. The four irrigation schedules were arranged as follows: application twice a week as S1, application once a week as S2, application once after every two weeks as S3 and a control (no irrigation at all) as S4. The treatments were replicated three times. Data was collected on the amount of irrigation water used, production cost, yield and income from the cabbages. The data were subjected to Analysis of Variance using SAS version 9.4. Mean separation was done using Fischer's least significant difference at P=0.05. An accounting profit approach was used to assess profitability from the selected irrigation schedules and varieties. The findings revealed that the yields of different cabbage varieties were not significantly different. Irrigation schedule 1 (S1) produced the highest average yield of 65.66 t ha-1 followed by S2 with 52.26 t ha-1 , S3 with 38.75 t ha-1 and S4 with 24.87 t ha-1 . Water use efficiency was significantly different across the four irrigation schedules. The control treatment plots recorded the highest water use efficiency at 70% in season one and 77% in the second season. Irrigation schedule 1 (S1) recorded the lowest water use efficiency of 46% in season one and 49% in season two which indicates that water productivity and efficiency reduced as the amount of water applied increased. In terms of production cost, S1 had the highest production cost ($2,103) but also gave the highest net revenue of $ 5,947 in season one and $ 4,460 in the second season. S4 recorded the least production cost ($1854) and net revenue ($1,575 in season one and $2,011 in season two). There were no significant differences among the three cabbage cultivars assessed in terms of production cost and net revenue in the second season. However, in season one, the cost of production for Triperio F1 variety ($2,019) was significantly different from that of Riana F1 and Gloria F1 cultivars ($1,959) while the latter two cultivars were not statistically different from each other. Net revenue for statistically different between Gloria F1 ($3,853) and Triperio F1 ($3,028) varieties but there were no significant differences between Gloria F1 and Riana F1 as well as Riana F1 and Triperio F1. These findings were significant for quantifying the impact of irrigation scheduling decisions with regard to water management in cabbage farming. The study therefore recommends adoption of irrigation schedule (S1) in order to optimize on cabbage yield reflected by the head weight and better stand count of the three cabbage varieties. There were no significant effects on the test cabbage varieties among the productivity parameters assessed under different irrigation schedules thus farmers may select any of the three cabbage varieties based on other production factors (agronomic variations, customer preference, and marketability)
Characterization and selection Anthracnose and Pythium root rot resistance in common bean landraces grown in Kenya
(UoEm, 2023-08) Misango, Shamir
Common bean (Phaseolus vulgaris L.) production in Kenya has not reached its potential yield due to various abiotic and biotic factors. Anthracnose, caused by Colletotrichum lindemunthianum and root rots caused by Pythium species are major production constraints. Landraces are preferred by farmers in Kenya due to yield stability and tolerance to some stresses. However, there is little information on the genetic diversity of the landraces and the level of resistance to anthracnose and Pythium root rot. The current study therefore focused on the following objectives (i) to characterize common bean landraces in Kenya based on morphological and simple sequence repeat (SSR) variations, (ii) screen for Pythium root rot and anthracnose resistance among Kenyan landraces and (iii) introgress anthracnose and Pythium resistance genes into farmer-preferred landraces. The study landraces were collected from farmers’ fields and local markets in western, central and eastern Kenya. The genetic diversity within the landraces was determined based on morphological data that was obtained from field experiments and simple sequence repeats (SSRs) markers. Commercial genotypes were included as checks in the study. The results showed significant differences (P≤0.05) among the genotypes for days to 50% flowering, days to plant maturity, leaf length, leaf width, number of pods per plant, number of seeds per pod, pod length, plant height, 100 seed weight and seed yield per plot, indicating high variability among the genotypes. In addition, 51 alleles were obtained from a set of 22 SSR markers, with a mean of 2.32 alleles. Through morphological cluster analysis, 4 distinct clusters were identified. The first cluster consisted of 20 large-seeded genotypes, the second cluster included 39 medium-seeded genotypes with a mixture of determinate and semi-determinate growth habits, the third cluster contained six medium-seeded indeterminate genotypes while the fourth cluster comprised of 34 small-seeded genotypes. Molecular analysis grouped the germplasm into three clusters. Cluster 1 was majorly composed of commercial genotypes of all seed sizes. Cluster 2 comprised of medium seeded genotypes while the third cluster comprised a mixture of genotypes with no unique observation within the clusters. Under greenhouse conditions, majority of the landraces were moderately resistant to anthracnose while most of the small seeded landraces were moderately resistant to Pythium root rot. None of the landraces possessed the molecular markers that are linked to anthracnose and Pythium root rot resistances. Three farmer-preferred landraces were selected for introgression of genes that confer resistance to anthracnose and Pythium root rot. The anthracnose differential cultivar, G2333, was used as the donor parent for anthracnose resistance in a marker assisted backcrossing scheme, while KK 8 was used as the donor parent for Pythium root rot resistance. Utilization of molecular markers enabled the development of 99 lines that carried Co 4 gene (anthracnose) and Pyult1 gene (Pythium). The introgression of disease resistance genes in landraces will ultimately enable bean growers achieve greater yields contributing to high income and improvement of their livelihoods. The information that was obtained from characterization of the landraces will inform breeders on suitable parents to use in breeding programs.
Characterization and selection Anthracnose and Pythium root rot resistance in common bean landraces grown in Kenya
(UoEm, 2023-08) Misango, Shamir
Common bean (Phaseolus vulgaris L.) production in Kenya has not reached its potential yield due to various abiotic and biotic factors. Anthracnose, caused by Colletotrichum lindemunthianum and root rots caused by Pythium species are major production constraints. Landraces are preferred by farmers in Kenya due to yield stability and tolerance to some stresses. However, there is little information on the genetic diversity of the landraces and the level of resistance to anthracnose and Pythium root rot. The current study therefore focused on the following objectives (i) to characterize common bean landraces in Kenya based on morphological and simple sequence repeat (SSR) variations, (ii) screen for Pythium root rot and anthracnose resistance among Kenyan landraces and (iii) introgress anthracnose and Pythium resistance genes into farmer-preferred landraces. The study landraces were collected from farmers’ fields and local markets in western, central and eastern Kenya. The genetic diversity within the landraces was determined based on morphological data that was obtained from field experiments and simple sequence repeats (SSRs) markers. Commercial genotypes were included as checks in the study. The results showed significant differences (P≤0.05) among the genotypes for days to 50% flowering, days to plant maturity, leaf length, leaf width, number of pods per plant, number of seeds per pod, pod length, plant height, 100 seed weight and seed yield per plot, indicating high variability among the genotypes. In addition, 51 alleles were obtained from a set of 22 SSR markers, with a mean of 2.32 alleles. Through morphological cluster analysis, 4 distinct clusters were identified. The first cluster consisted of 20 large-seeded genotypes, the second cluster included 39 medium-seeded genotypes with a mixture of determinate and semi-determinate growth habits, the third cluster contained six medium-seeded indeterminate genotypes while the fourth cluster comprised of 34 small-seeded genotypes. Molecular analysis grouped the germplasm into three clusters. Cluster 1 was majorly composed of commercial genotypes of all seed sizes. Cluster 2 comprised of medium seeded genotypes while the third cluster comprised a mixture of genotypes with no unique observation within the clusters. Under greenhouse conditions, majority of the landraces were moderately resistant to anthracnose while most of the small seeded landraces were moderately resistant to Pythium root rot. None of the landraces possessed the molecular markers that are linked to anthracnose and Pythium root rot resistances. Three farmer-preferred landraces were selected for introgression of genes that confer resistance to anthracnose and Pythium root rot. The anthracnose differential cultivar, G2333, was used as the donor parent for anthracnose resistance in a marker assisted backcrossing scheme, while KK 8 was used as the donor parent for Pythium root rot resistance. Utilization of molecular markers enabled the development of 99 lines that carried Co 4 gene (anthracnose) and Pyult1 gene (Pythium). The introgression of disease resistance genes in landraces will ultimately enable bean growers achieve greater yields contributing to high income and improvement of their livelihoods. The information that was obtained from characterization of the landraces will inform breeders on suitable parents to use in breeding programs.
Prevalence and host resistance to Common bean rust Disease In Central and Western Kenya
(UoEm, 2023-08) Wafula, Brian Wekesa
Rust (Uromyces appendiculatus) (Pers.:Pers.) Unger., is among the most destructive pathogens constraining the production of common beans (Phaseolus vulgaris L.) in Kenya. The study's objectives were to (i) determine the prevalence of bean rust in central and western Kenya; (ii) evaluate common bean genotypes for host resistance to rust disease under field and greenhouse conditions; (iii) characterize the Ur gene in a French bean breeding line MU#13; and (iv) identify SSR markers linked to the Ur gene in a French bean breeding line MU#13. A field survey was conducted in 150 farmers’ fields in 5 counties in Kenya from September 2020 to January 2021. During the survey, germplasm and rust isolates were collected for screening in the field and under greenhouse conditions. A total of 77 common bean genotypes were subjected to natural infection under field conditions and inoculated with rust races 29-1, 29-3, 61-1, and 63-1 under greenhouse conditions at the University of Embu. The gene pool affiliation of the genotypes was determined through phaseolin protein marker analysis. Further, F2 populations that were obtained from a cross between a French bean breeding line (MU#13) and 13 known Ur gene sources were screened using bean rust isolates to characterize the Ur gene in MU#13. Bulk segregant analysis (BSA) using 14 SSR primers and the DNA obtained from susceptible parent Amy, MU#13 (resistant parent), and the F2 plants, as well as RILs, was used in the identification of SSRs linked to the Ur gene in MU#13. The collected rust incidence and severity data were subjected to an analysis of variance using GenStat statistical software. The goodness-of-fit of hypothetical ratios in the F2 mapping populations was assessed using the Chi-square test. The findings revealed a resurgence of bean rust, with Bungoma County displaying the highest disease incidence at 71% and a severity rating of 4. On the other hand, Embu County exhibited the lowest incidence at 38% and a severity rating of 2. The common bean cultivar grown, debri management, management of volunteer plants, use of fungicides, and crop spacing significantly (p<0.01) influenced bean rust incidence and severity. However, cropping system, source of seeds, and previous crop did not significantly influence rust prevalence. A significant level of variability was observed among the 77 bean genotypes in their reaction to bean rust. The genotypes KMR 11 (Angaza), Kat X56, UN6-Nakholo, UN2-Darkgreen, Enclave, Manakelly, and MU#13 were the most resistant, while Mexico 222, Widusa, Mitchelite, Amy, Samantha, Julia, GBK-032805, and UN4-Yellow small were the most susceptible to rust. Generally, common bean genotypes of Mesoamerican origin were more resistant to rust as compared to those of Andean origin. The study further revealed a potentially new gene in MU#13. The SSR PV-ctt001, the only informative marker identified through BSA, was loosely linked to the gene, limiting its utility and therefore the need for the development of robust markers tagging the gene. This study provides baseline information for common bean rust occurrence in the two regions in Kenya and resistance sources to aid in the control of the rust disease.
Marker assisted Selection for resistance to bean common Mosaic Necrosis virus In French Bean cultivars in Kenya -
(UoEm, 2023-08) Watare, Grace Wambui
Worldwide, commercial production of French bean (Phaseolus vulgaris L.) is constrained by diseases, key among them being the bean common mosaic virus (BCMV) and bean common mosaic necrosis virus (BCMNV). These potyviruses are the most devastating to common bean farmers and can cause total yield loss under heavy infestation. The objective of this study was to characterize the BCMNV resistance in commercial French bean cultivars and initiate a breeding program against the disease. A set of 32 entries, comprising 27 French bean genotypes together with 5 dry bean varieties were evaluated for resistance under field conditions. All the 29 French bean genotypes showed susceptibility to BCMNV but the 3 dry bean resistant checks (MCM 2001, MCM 5001 and MCM 1015) were resistant to the disease. The French bean cultivars displayed varied reactions to BCMNV pathotypes III and VI under greenhouse conditions ranging from top necrosis, mosaics, mottling, and deformed leaves to stunted growth. In this study, molecular marker SW13 and SBD5 were used to detect the presence of the I gene and the bc-12 gene, respectively. ROC11 and CAPS elF4E that are linked to BCMNV bc-3 gene, were also used to detect specific resistance genes. Molecular analyses showed that only SW13 and elF4E markers were consistent in identifying the presence/absence of the I and bc-3 gene, respectively. The two molecular markers and ROC-11 were successfully utilized in the introgression of bc-3 gene into three commercial French bean cultivars (Amy, Serengeti and Vanilla) in a backcross breeding program involving MCM 2001, MCM 5001 and MCM 1015 as donor parents. From the breeding program, 19 breeding lines combining field resistance against both BCMNV and BCMV were developed. The selected lines were further phenotypically evaluated for quality and yield traits such as pod length, pod quality, pod suture string, pod wall fiber, pod yield and the number of pods per plant. The results confirmed significant maintenance of the yields and quality traits among the 19 selections. The developed breeding lines will be further screened and improved for release as new French bean cultivars thus enabling the production of this valuable vegetable in areas where these potyviruses are prevalent. In addition, the developed lines can be utilized as sources of BCMNV resistance in future breeding programs. Availability of reliable sources of BCMNV resistance within French bean gene pool will simplify the future breeding programs.
Productivity and Profitability of Selected Cabbage Varieties Under Varying Drip Irrigation Schedules in Humic Nitisols of Embu County
(UoEM, 2022-08) Onkoba, Stephen Onyiego
The adverse effects of climate change and increasing human population have put pressure on scarce water resources used in crop production. This consequently threatens the food and nutritional security of the growing human population. Vegetables are short season crops that are sensitive to water deficits during growth, leading to low productivity, poor marketability and reduced household incomes. Use of controlled irrigation in production of vegetables is considered a sustainable route for enhancing input use and productivity. This study sought to evaluate the effects of crop variety and drip irrigation schedules on productivity and profitability of cabbage grown in humic nitisols in Embu County, Kenya. The study applied a split plot laid in Randomized Complete Block Design (RCBD) in which the drip irrigation schedules were allocated the main plot and crop varieties were allocated the sub-plot treatments. The test varieties investigated were Riana F1, Gloria F1 and Triperio F1. The four irrigation schedules were arranged as follows: application twice a week as S1, application once a week as S2, application once after every two weeks as S3 and a control (no irrigation at all) as S4. The treatments were replicated three times. Data was collected on the amount of irrigation water used, production cost, yield and income from the cabbages. The data were subjected to Analysis of Variance using SAS version 9.4. Mean separation was done using Fischer's least significant difference at P=0.05. An accounting profit approach was used to assess profitability from the selected irrigation schedules and varieties. The findings revealed that the yields of different cabbage varieties were not significantly different. Irrigation schedule 1 (S1) produced the highest average yield of 65.66 t ha-1 followed by S2 with 52.26 t ha-1 , S3 with 38.75 t ha-1 and S4 with 24.87 t ha-1 . Water use efficiency was significantly different across the four irrigation schedules. The control treatment plots recorded the highest water use efficiency at 70% in season one and 77% in the second season. Irrigation schedule 1 (S1) recorded the lowest water use efficiency of 46% in season one and 49% in season two which indicates that water productivity and efficiency reduced as the amount of water applied increased. In terms of production cost, S1 had the highest production cost ($2,103) but also gave the highest net revenue of $ 5,947 in season one and $ 4,460 in the second season. S4 recorded the least production cost ($1854) and net revenue ($1,575 in season one and $2,011 in season two). There were no significant differences among the three cabbage cultivars assessed in terms of production cost and net revenue in the second season. However, in season one, the cost of production for Triperio F1 variety ($2,019) was significantly different from that of Riana F1 and Gloria F1 cultivars ($1,959) while the latter two cultivars were not statistically different from each other. Net revenue for statistically different between Gloria F1 ($3,853) and Triperio F1 ($3,028) varieties but there were no significant differences between Gloria F1 and Riana F1 as well as Riana F1 and Triperio F1. These findings were significant for quantifying the impact of irrigation scheduling decisions with regard to water management in cabbage farming. The study therefore recommends adoption of irrigation schedule (S1) in order to optimize on cabbage yield reflected by the head weight and better stand count of the three cabbage varieties. There were no significant effects on the test cabbage varieties among the productivity parameters assessed under different irrigation schedules thus farmers may select any of the three cabbage varieties based on other production factors (agronomic variations, customer preference, and marketability).
Performance of Sorghum Hybrid Lines with Tannin Gene from Crosses between Gadam and Tannin Hard Coat Sorghum Varieties
(University of Embu, 2021-09) Shinda, Cecilia Adhiambo
Sorghum is a major staple food source in many African countries. In Kenya, it is cultivated by small-scale farmers. Gadam sorghum is the common variety mainly grown for brewing, manufacture of animal feeds and sorghum cakes. However, its yield is about 0.8 t ha- which is low compared to international standards. This is exacerbated by birds' that tend to have a preference for it. The use of birds' resistant sorghum varieties containing higher amounts of tannin than Gadam is a strategy to minimize the damage. However, tannin is an anti-nutritional factor that binds proteins together and inhibits many enzymes in in vitro assays reducing their digestibility and efficiency of utilization. Production of hybrids is one way of improving yield through heterosis. The objective of this study was to evaluate the performance of sorghum through hybridization of Gadam sorghum and hard coat tannin sorghum varieties. The study was conducted at the University of Embu research farm. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replicates. Four (4) sorghum varieties namely, Serena, Gadam, Seredo and Kari/Mtama-1 (used as a control due to its low tannin content) were sourced from the KALRO seed unit at Katumani. Sowing of sorghum varieties was staggered over three weeks to synchronize heading time to enable crossing. Development of F1 hybrid lines was done by reciprocal crossing of Gadam and other varieties, using manual emasculation method. Crosses and their reciprocals were used as plant materials while parents were the controls. Data taken was; compatibility between the parents, changes in levels of expression of the tannin gene, grain nutritional levels, heterosis and yield traits compared to their parents. Collected data was subjected to a one-way analysis of variance (ANOVA) using R statistical software. Mean separation was done using Tukey’s Studentized Range (HSD) at 95% confidence level. The cross Gadam x Serena, Serena x Gadam and the parent Gadam exhibited moderate mean plant height values of 99.5 cm, 120.5 cm and 103.3 cm respectively. The cross Gadam x Serena recorded a desirable negative mid-parent heterosis of -19.89 and -16.16 for plant height and days to maturity respectively. All F1 hybrids recorded positive mid parent heterosis for the weight of full panicle, weight of a thousand seeds, number of tillers per plant, number of reproductive tillers and panicle length indicating possible yield improvement of Gadam sorghum through hybridization. The crosses Gadam x Seredo, Seredo x Gadam, Gadam x Serena and Kari/Mtama-1 x Gadam recorded significantly lower grain filling percentages compared to their parents. Both RNA levels and tannin content were observed to be at the maximum at soft dough stage and declined in subsequent stages indicating synchrony between RNA levels and tannin levels. Parents, crosses and reciprocals also differed significantly (p<0.001) for crude protein, fat, crude fibre, ash, carbohydrates, moisture and tannin content with values ranging from 5.323% to 10.390%, 1.691% to 2.299%, 2.230% to 3.520%, 1.215% to 1.360%, 76.790% to 85.677% , 5.433% to 9.667% and 0.034 mg/g to 1.763 mg/g respectively. In conclusion, all the F1 hybrids have positive mid parent heterosis for number of reproductive tillers, number of tillers per plant, panicle length, weight of full panicle, and a thousand seed weight. There is maternal influence on days to heading, flowering and maturity, and a thousand grain weight. The lower grain filling percentage recorded in the F1 hybrids indicates that the parental lines used have a narrow wide compatibility gene. The decline in Tan1 gene after the soft dough stage shows that Tan1 gene expression in sorghum is determined by the level of seed maturity. The F1s showed marginal improvement in crude protein, crude fibre and carbohydrates but need to be evaluated further to determine the influence of hybridization on total nutrition. Also, heterosis can be utilized to improve the growth and yield of sorghum.
Contributions of Anthropogenic Activities to Leaf Litter Decomposition in River Kapingazi, Embu County, Kenya
(University of Embu, 2021-09) Nyambane, Neliah Moraa
Human activities have potential adverse effects on freshwater ecosystems, which sustain a wide range of ecosystem services such as the provision of potable water, nutrient cycling, and a habitat for organisms such as decomposer macro-invertebrates. The effect of these activities with regard to water quality and invertebrates has been established and well documented. However, information on the effect of human activities on leaf litter breakdown as an indicator of river ecosystem integrity is still limited in Kenya. The objectives of the study were: To determine effect of anthropogenic activity on litter decomposition rates of Lantana camara, Eucalyptus grandis and Psidium guajava; to compare leaf litter decomposition rates of the three species and To examine relationships between leaf litter decomposition rates, macro invertebrate shredders and water quality parameters. The study employed the litterbag method where dry leaves enclosed in mesh bags were incubated in the river to measure mass loss decomposition and associated macro invertebrates. Data was collected from September to December 2018.iThe Physicochemical characteristics of water measured in-situ included electrical conductivity (EC), pH, total dissolved solids, dissolved oxygen (DO) concentration and temperature. Further, water discharge, velocity, depth and width were determined. Laboratory analyses were conducted to determine concentration of nitrates, nitrites, total phosphorus and phosphates. Daily mass loss of the collected bags was determined to assess litter decomposition rates. Macro invertebrates identified were classified up to family level and grouped into functional feeding groups. Data was analyzed using R statistical packages. Findings show that site and plant species had a significant effect (p=0.05) on leaf litter decomposition rates. Of the three species, Lantana camara had the fastest decomposition irate while Psidium guajava had the slowest irate of decomposition. Water physicochemical parameters had both positive and negative correlation with leaf litter decomposition rates and no macro invertebrate shredders were observed. It is recommended that future studies should evaluate other human activities (for example, mining and waste water effluents) and effects of leaf litter mixtures on the decomposition process.
Adoption of Selected Climate Smart Agriculture Technologies among Smallholder Farmers in Lower Eastern Kenya
(University of Embu, 2021-09) Muriithi, Lydia Nyawira
Climate change has greatly affected food production and food security. Erratic temperature rises and inconsistent precipitation have greatly influenced productivity of crops and livestock. The impacts have gotten much more pronounced among small scale farmers in Kenya whose farming activities are climate reliant. As a component of climate change adaptation, selecting suitable climate smart agriculture (CSA) technologies that can alleviate these adverse consequences is critical. The study sought to determine the factors affecting adoption of selected climate smart agriculture technologies among smallholder farmers in Lower Eastern Kenya, comprising of Machakos, Kitui and Makueni Counties. A sample of 384 households was obtained using multi-stage sampling procedure. A semi-structured questionnaire designed in an open data kit (ODK) application was used to collect primary data from the sampled smallholder farmers. The main adaptation technologies considered were mixed farming, intercropping, crop rotation, conservation agriculture, agroforestry, crop diversification and water harvesting, in that order. Descriptive statistics (frequency and percentages) were used to analyze socio-economic characteristics. Findings revealed that 54.2% of the respondents were males and 35.7% in their productive years (36-50 years). In addition, the findings revealed that most of the interviewed farmers (97.4%) had observed climate change and the effect on food production. Results of the multinomial regression on socio-economic and climate information pathways revealed a positive impact of gender and education level on uptake of crop rotation (0.7%), agroforestry (0.9%) and crop diversification (0.4%) while reliance on mobile phones (0.9%) and neighbors/friends (0.2%) reduced adoption of water harvesting. Multivariate probit model was employed to analyze socio-economic and institutional factors influencing adoption. The likelihood of adopting mixed farming, intercropping and crop rotation significantly increased (p<0.05) among male-headed households and having adequate access to off-farm income and credit facilities. Further, a Food Consumption Score (FCS) was employed to compare quantity and quality of food consumed among households across the three counties. Kitui County had the highest poor FCS at 80% due to lack of adequate knowledge on proper use of the technology than was the case in Kitui (72.5%) and Makueni (73%) Counties. This study therefore recommends promoting adoption of the disseminated CSA technologies, providing reliable extension services plus accessibility to other essential services, like, fertilizer and seeds markets for realizing increased agricultural production in Lower Eastern Kenya.
Characterization of Smallholder Farming Systems And Greenhouse Gas Emissions Simulation From Maize Cropping System in Tharaka-Nithi County, Kenya
(University of Embu, 2020-12-11) Musafiri, Collins, Muimi
The influence of soil fertility management technologies on crop production has widely been researched in Tharaka-Nithi County. However, data on their contribution towards national greenhouse gas budget is scanty. This study aimed at characterising smallholder farming systems and simulating greenhouse gas emissions, maize yields, yield scaled nitrous oxide (N2O) emissions and N2O emission factors from different soil fertility management technologies in Tharaka-Nithi County. Three hundred households were interviewed to obtain data for farming systems characterisation and evaluation of socioeconomic factors influencing the diversity of farm typologies. Interview schedules were administered using open data kit collect mobile App. Multivariate analysis was done to characterise smallholder farming systems. To evaluate socio-economic factors influencing farm diversity, Chi-square, t-test, and multinomial regression analysis were carried out using the Statistical Package for Social Sciences (SPSS version 23). For calibration and validation of the DeNitrification DeComposition (DNDC) model, a oneyear soil greenhouse gas quantification experiment data were used. The data were obtained from a field experiment conducted in Kigogo primary school. It was laid out in randomised complete block design under four soil fertility treatments as control (no external inputs), inorganic fertiliser (NP, 23.23, 120 kg N ha ), animal manure (goat manure, 120 kg N ha -1 -1 yr -1 ) replicated thrice. Climate, soil properties, N2O fluxes, maize yields and farm management data were used. The model was evaluated using modelling efficiency, mean error, coefficient of determination, mean absolute error, and root mean square error (RMSE). The experimental data were subjected to Analysis of Variance in SAS 9.4 software and mean separation done using least significance difference at p = 0.05. The results showed six farm types: Type 1, comprising cash crop and hybrid cattle farmers; Type 2, involving food crop farmers; Type 3, composed of coffee-maize farmers; Type 4, consisting of millet-livestock farmers; Type 5, comprising highly diversified farmers, and Type 6, had tobacco farmers. Land size, total tropical livestock unit, the proportion of land and amount of nitrogen applied to different cropping systems were significant in the construction of farm typologies. The DNDC model was fair in simulating daily N2O fluxes (54% ≤ normalized RMSE (nRMSE) ≤ 68% and 0.26 ≤ modelling efficiency (MEi) ≤ 0.49) and good to excellent performance in simulating cumulative annual soil N2O fluxes (6.16 ≤ nRMSE ≤ 12.86 and 0.63 ≤ MEi ≤ 0.86) across soil fertility treatments. The cumulative observed and simulated annual soil N2O fluxes ranged between 0.21±0.01 and 0.38±0.02 kg N2O-N ha -1 yr ) and animal manure + inorganic fertiliser (120 kg N ha -1 -1 yr (control) to 0.38 (fertiliser) kg N2O-N ha -1 -1 yr and 0.20 kg N2O-N ha -1 -1 yr . The simulated N2O yield scaled emissions, and emission factors ranged from 0.022 to 0.029 g N Kg -1 -1 yr grain yield and 0.03 % to 0.14% under manure and fertiliser treatments, respectively. Based on the low observed and simulated emission factors, using the Intergovernmental Panel on Climate Change (IPCC) Tier 1 default factor of 1% overestimates agricultural soils GHG emissions in the Central Highlands of Kenya. Manure and fertiliser combination should be promoted to enhance the three pillars of climate-smart-agriculture (CSA) as food security, climate change mitigation and adaptation. -1
Adsorptive Ability of Banana Stalks Biochar in Greywater Remediation for Reuse: A Case of University of Embu, Kenya
(University of Embu, 2020-12-11) Ndung'u, Paul
The global demand for fresh water resources has been increasing over the years due to population growth, urbanization, industrialization, climate change and the global warming effect. The available water resources have reduced over time leaving a water demand deficit. Recycling and reuse of greywater has been touted as one of the strategies to augment the existing water resources. This study characterized the greywater from students’ hostels and prepared biochar from banana stalks for use as an adsorbent in greywater remediation. The study found significant differences in greywater quality based on source, day and time of sampling. The biochar produced through pyrolysis at pyrolytic temperatures of 300 °C, 400 °C and 500 °C showed the presence of hydroxyl and carboxyl surface functional groups responsible for adsorption of target contaminants. The biochars achieved varying percentage reduction of the selected parameters with biochar prepared at temperature 500 °C recording a significantly higher (p≤ 0.05) percentage removal of Na + + and COD at 65.43%, 89.36% and 60.60% when compared to 58.30%, 56.96% and 49.51% for biochar 400 , K C, and 41.13%, 40.36% and 38.31% for biochar 300 °C, respectively. Biochar produced at temperature 300 °C exhibited a significantly higher (p≤ 0.05) reduction of BOD in the greywater of 71.28% as compared to biochars 400 °C and 500 °C which had 66.64% and 61.92% percentage reduction, respectively. Biochar 500 °C was found most suitable for Na ° an COD reduction while Biochar 300 °C most suited the BOD reduction. The results from this study showed that biochar produced from banana stalks can be used as an adsorbent for greywater remediation and the treated water was suitable for consideration in agricultural reuse under the test conditions.

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