Master Theses: Department of Water and Agricultural Resource Management

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Effects of Tillage Method and Sowing Time on Growth, Water Use and Yield of Chickpea (Cicer arietinum L.) in Kenyan Dry
(Egerton University, 2007) Onyari, Charles N.
The need to provide sufficient protein food for an increasing population that is mainly resource poor requires opening up of marginal land for growing appropriate pulsessuch as chickpea. An experiment was carried out at KARI-Naivasha situated at an altitude of 1900 m, characterized with clayey to sandy loam soils in a split plot of randomized complete block design over two seasons (December 29, 2004 to May 26, 2005 and June 21 to November 15, 2007). The objective was to investigate the production of kabuli chickpea in Kenya as affected by tillage methods (main plots) and sowing times (subplots) and the effects of these factors on water use and yield ofthe crop. The overall mean height ranged from 39.7 to 47.7 cm under tillage methods with strip tillage resulting in relatively taller plants than the other tillage methods. Sowing times gave plant heights of 41.5 – 46.4 cm with early sown crops being relatively taller than late sown crop in both seasons. The leaf area index ranged from 2.50 to 3.31 and 4.22 to 5.44 under tillage methods in Season I and II, respectively. The corresponding valuesof LAI in the respective two seasons under sowing times were 2.80 to 3.20 and 3.59 to 5.69. Thecrop took 32.5 to 35.5 days to first flower and 61.8 to 61.4 days to 50% flowering in Season I and II, respectively. The mean time to physiological maturity was 120 days showed significant differences among tillage methods in both seasons. The time to first flower and 50% flowering however had non-significant differences (P<0.05) under both tillage method and sowing time treatments. The aboveground biomass yield of the chickpea varied from 3242.1 to 4231.3 kg ha -1 in Season I and 3035.8 to 4556.1 kg ha -1 in Season II under varying tillage treatments. The sowing time effects on biomass yield showed significant differences in biomass yields ranging between 3784.3 to 4095.0 kg ha -1 and 2938.1 to 4263.2 kg ha -1 in Season I and II, respectively. The grain yields obtained were significantly different (P<0.05) ranging from 1430.6 to 2544.9 kg ha -1 under tillage method effects and 1573.8 to 2235.3 kg ha -1 under sowing time treatment effects in both seasons. Tillage and sowing time effects on grain yield of chickpea were significantly different (P<0.05) only in the second season. In Season I, rains received in the post anthesis period of the chickpea thus causing it to exhibit indeterminate growth habit which resulted in additional yield increments of between 26.2 to 29.8% and 23.3 to 35.0% under various tillage and sowing time treatments, respectively. This gave a final overall mean grain yield of 2058.4 ka ha -1 . The 100-grain weight of the chickpea varied between 36.7 to 40.2 g in both seasons and showed non-significant differences under both factors of study. Infiltration rates were not significant under tillage and sowing times but affected the storage capacity ranging between 450.3 mm for first sowing time in Season II to 488.1 mm for conventional tillage in Season I. The mean seasonal evapotranspiration varied between 300.1 mm to 326.1 mm and showed interaction effects between tillage and sowing times in Season II. The mean biomass based water use efficiency (WUE b) and grain based water use efficiency (WUE g) ranged from 12.09 to 12.21 kg ha-mm -1 and 4.93 to 6.31 kg ha-mm -1 in Season I and II, respectively. The moisture use rate was non-significant with ranges of 2.23 to 2.58 and 2.18 to 2.56 mm/day in Seasons I and II, respectively.
Effects of Tillage Method and Sowing Time on Growth, Water Use and Yield of Chickpea (Cicer arietinum L.) in Kenyan Dry Highlands
(2010) Onyari, Charles N.
The need to provide sufficient protein food for an increasing population that is mainly resource poor requires opening up of marginal land for growing appropriate pulses such as chickpea. An experiment was carried out at KARI-Naivasha situated at an altitude of 1900 m, characterized with clayey to sandy loam soils in a split plot of randomized complete block design over two seasons (December 29, 2004 to May 26, 2005 and June 21 to November 15, 2007). The objective was to investigate the production of kabuli chickpea in Kenya as affected by tillage methods (main plots) and sowing times (subplots) and the effects of these factors on water use and yield of the crop. The overall mean height ranged from 39.7 to 47.7 cm under tillage methods with strip tillage resulting in relatively taller plants than the other tillage methods. Sowing times gave plant heights of 41.5 – 46.4 cm with early sown crops being relatively taller than late sown crop in both seasons. The leaf area index ranged from 2.50 to 3.31 and 4.22 to 5.44 under tillage methods in Season I and II, respectively. The corresponding values of LAI in the respective two seasons under sowing times were 2.80 to 3.20 and 3.59 to 5.69. The crop took 32.5 to 35.5 days to first flower and 61.8 to 61.4 days to 50% flowering in Season I and II, respectively. The mean time to physiological maturity was 120 days showed significant differences among tillage methods in both seasons. The time to first flower and 50% flowering however had non-significant differences (P<0.05) under both tillage method and sowing time treatments. The aboveground biomass yield of the chickpea varied from 3242.1 to 4231.3 kg ha-1 in Season I and 3035.8 to 4556.1 kg ha-1 in Season II under varying tillage treatments. The sowing time effects on biomass yield showed significant differences in biomass yields ranging between 3784.3 to 4095.0 kg ha-1 and 2938.1 to 4263.2 kg ha-1 in Season I and II, respectively. The grain yields obtained were significantly different (P<0.05) ranging from 1430.6 to 2544.9 kg ha-1 under tillage method effects and 1573.8 to 2235.3 kg ha-1 under sowing time treatment effects in both seasons. Tillage and sowing time effects on grain yield of chickpea were significantly different (P<0.05) only in the second season. In Season I, rains received in the post anthesis period of the chickpea thus causing it to exhibit indeterminate growth habit which resulted in additional yield increments of between 26.2 to 29.8% and 23.3 to 35.0% under various tillage and sowing time treatments, respectively. This gave a final overall mean grain yield of 2058.4 ka ha-1. The 100-grain weight of the chickpea varied between 36.7 to 40.2 g in both seasons and showed non-significant differences under both factors of study. Infiltration rates were not significant under tillage and sowing times but affected the storage capacity ranging between 450.3 mm for first sowing time in Season II to 488.1 mm for conventional tillage in Season I. The mean seasonal evapotranspiration varied between 300.1 mm to 326.1 mm and showed interaction effects between tillage and sowing times in Season II. The mean biomass based water use efficiency (WUEb) and grain based water use efficiency (WUEg) ranged from 12.09 to 12.21 kg ha-mm-1 and 4.93 to 6.31 kg ha-mm-1 in Season I and II, respectively. The moisture use rate was non-significant with ranges of 2.23 to 2.58 and 2.18 to 2.56 mm/day in Seasons I and II, respectively.
Effects of Tillage and Mulching on Maize Yield, Soil Water Content and Organic Carbon in Kirige, Tharaka-Nithi County. Kenya
(University of Embu, 2016-09) Njogu, Evelyn W.
Sustainable agricultural production in Kenya requires improvement of yields per unit of land while still conserving soil resources. Besides poor soil nutrient status, water is a limiting factor to crop production in the rain-fed farming systems of central highlands of Kenya. Hence, there is need to address soil water scarcity challenges in order to increase crop production. The objective of the study was to determine the effects of tillage and mulching on maize (Zea Mays. L) yield, soil water content and organic carbon of Humic nitisols in the central highlands of Kenya. The study was conducted in Tharaka-Nithi County, Meru South Sub-County at Kirege for two seasons (long rains 2014 and short rains 2014). Two mulch levels; removal (W) and retention (R) of crop residue were applied randomly to plots measuring 7 m by 7 m under two tillage methods; conventional tillage (CT) and minimum tillage (MT). The treatments arrangement was a split-plot laid down in a randomized complete block design. Data on soil organic carbon, soil moisture, grain and biomass yield was subjected to Analysis of variance (ANOVA) using the mixed model in SAS 9.3. The soil organic carbon content data at the beginning and end of the experiment was subjected to student t-test for pair wise comparisons using the mixed model in SAS 9.3. Difference between treatment means was tested using least significant difference at 5% level of significance. The results showed significant tillage (p=0.0042) and mulching (p=0.0255) singular effect on maize yield. Combining tillage and mulching significantly (p=0.039) increased maize stover and grain yields. Overall, conventional tillage with residue treatment gave the highest increase in stover yield by 72%. Minimum tillage with residue and without residue, increased grain yield by over 50% compared to conventional tillage with and without residue. In the short term, soil water was not significantly influenced singly by tillage and mulching but it was positively influenced by tillage and mulch combination. On average, minimum tillage with residue and without residue increased soil moisture content by 10 and 7%, respectively compared to control, while Conventional tillage with residue and without residue increased moisture by 4 and 3% respectively. Tillage alone significantly (p=0.01) affected soil organic carbon content while mulching alone did not. There was significant (p=0.01) increase in soil organic carbon under minimum tillage as opposed to the reduction under conventional tillage at the 0–0.2 m soil depth. Combining tillage and mulching resulted to higher soil organic carbon content. Minimum tillage with residue, increased soil organic carbon by 0.33% more than minimum tillage alone. Short-term implementation of minimum tillage and mulching under the soil and climate conditions prevailing in Kirege Tharaka-Nithi County enhances maize production while improving soil conditions in terms of soil moisture and organic carbon content.
Integrated Soil Nutrient Management Technologies for Improved Maize (Zea Mays L.) Productivity in Murang’a and Tharaka-Nithi Counties, Kenya
(University of Embu, 2018-09) Otieno, Erick Oduor
Continuous land cultivation without adequate soil nutrients replenishment causes soil fertility decline leading to reduced crop productivity. Significant research on external fertility inputs application rates and type have been carried out under researcher designed and managed conditions in Kenya. But little research on the same has been carried out to evaluate their performances under on-farm smallholder farmers’ conditions. Hence, the study evaluated the decomposition rates (goat manure and Tithonia diversifolia) and performance of selected integrated soil nutrients management technologies on soil nutrients amounts and maize productivity under two tillage methods. On-farm trials were laid out in randomized incomplete block design. There were two control treatments; conventional tillage-control (CON-C) and minimum tillage-control (MIN-C). Each tillage method was combined with different soil fertility inputs. Soil fertility inputs included mineral fertilizer, rock phosphate, crop residue, legume intercrop, goat manure and Tithonia diversifolia. Compared to CON-C, in Meru South, N and K significantly increased under minimum tillage+crop residue+Tithonia diversifolia+goat manure and minimum tillage+crop residue+Tithonia diversifolia+rock phosphate by 100 and 52%, respectively. In Gatanga, nitrogen, phosphorus and potasium significantly increased under minimum tillage+mineral fertilizer, conventional tillage+crop residue+mineral fertilizer+goat manure and minimum tillage+crop residue+goat manure+legume intercrop by 33, 78 and 34%, respectively. The highest decomposition rate constants were 0.024 and 0.015 d-1, and 0.020 and 0.014 d-1 for Tithonia diversifolia and goat manure in Meru South and Gatanga, respectively. Relative to CON-C, minimum tillage+crop residue+Tithonia diversifolia+rock significantly increased maize grain yield by 89 and 91% in Meru South and Gatanga during SR2016 and LR2016, respectively. The selected soil nutrient management technologies were preferred based on the ability to improve soil fertility, crop yield, ease of implementation, availability of inputs and labour and farmer’s age. The study concludes that selected soil nutrients technologies improve soil fertility and maize grain and stover yields thus are likely to be taken up by farmers. Tithonia diversifolia and goat manure can be used to synchronize crop-nutrient release.
Rainfall Characteristics and Effect of Selected Soil Management Practices on Soil Water Productivity in the Central Highlands of Kenya
(University of Embu, 2018-09) Oduor, Nathan Okoth
Water insufficiency due to scarcity, poor distribution and high variability of rainfall in the Central Highlands of Kenya (CHK) and a decline in soil fertility have contributed to a continuous decrease in water productivity. To increase food production to match the growing population, soil management practices that ensure improved water productivity should be embraced. The study, therefore, sought to characterize rainfall and to establish the effects of selected soil management practices on water productivity in Tharaka-Nithi and Murang’a Counties. The field experiments were laid in Meru South sub-County, Tharaka-Nithi County and Gatanga sub-County, Murang’a County. Rainfall characterisation was done in seven Counties in the C; Meru, Embu, Nyeri, Kirinyaga and Kiambu plus the two Counties where the field experiments were laid. Statistical methods and programs used in rainfall characterisation included RAIN software, cumulative departure index (CDI), rainfall anomaly index (RAI), a coefficient of variation (CV), precipitation variability index (PVI), correlation coefficient, root mean square error and scatter plots. The field experiment was laid in a randomised complete block design with tillage and soil inputs as combined treatments. The treatments in each site were: control, sole mineral fertiliser, crop residues plus mineral fertiliser, crop residues plus mineral fertiliser plus animal manure, crop residues plus Tithonia diversifolia plus rock phosphate, crop residues plus animal manure plus legume intercrop, crop residues plus Tithonia diversifolia plus animal manure. The treatment combinations were laid under both conventional and minimum tillage (MT). Test crop was maize (Zea Mays L.), H516. Soil moisture, soil water productivity and soil physical properties (Bulk density, saturated hydraulic conductivity and aggregate stability) under different treatments were subjected to analysis of variance (ANOVA) in SAS 9.3 software. Differences between treatment means were separated using Duncan's Multiple Range Test (DMRT) at p≤0.05. Rainfall analysis showed that rainfall in the CHK was highly variable temporally and spatial though fairly distributed. There was a high frequency of dry spell with high probability (93%) of future occurrence. Satellite and observed rain gauge data showed close agreement at seasonal scale than at daily scale. Satellite estimates can be used to substitute observed rain gauge data. The experimental results showed treatments had significant effect on soil moisture at 0-10 cm, 10-20 cm, 20-30 cm and at 30-40 cm depths (p=0.0001). Treatment under conventional tillage (CT) plus crop residue plus Tithonia diversifolia plus animal manure (CtRTM) had the highest soil moisture. Treatments had a significant effect on soil water productivity at 0-10 cm, 10-20 cm, 20-30 cm and at 30-40 cm depths in Chuka while in Kandara, the significant difference was only at 0-10 cm depth. Treatments under CT plus crop residue plus mineral fertiliser with or without animal manure (CtRFM/ CtRF) had the highest soil water productivity. Treatments had no significant effect on soil bulk density, saturated hydraulic conductivity and aggregate stability in the two sites. The result of the experiment will be used by various stakeholders in agriculture for planning and decision-making purposes regarding water productivity. It will also provide a baseline for further research and development.
Enhancing Soybean Production, Economics and adoption among Smallholder Farmers in the Central Highlands of Kenya
(University of Embu, 2019-08) Murage, Francis M.
Current demand for soybean in Kenya is higher than production. The deficit which is over 95% is filled through importation from neighboring countries. Despite the high demand, adoption and production is low (0.56 to 1.1 t ha-1) against potential yield of 3.0 – 3.6 t ha-1. The low production is associated with low use of fertilizers. Farmers are using mineral fertilizers below recommended rates and they are not using organic fertilizers despite them being readily available. The objectives of the study was therefore to determine the effect of applying organic and inorganic fertilizers singly or in combination on grain yield of soybean, compare economics of soybean under organic and inorganic fertilizers and to determine factors influencing adoption of soybean by smallholder farmers in the central Highlands of Kenya. To achieve these objectives, on-farm experiments were set in Embu County and a survey was carried out in Embu, Meru and Tharaka Nithi Counties. The experiments had six treatments; (tithonia, tithonia plus fertilizer, fertilizer plus manure, fertilizer, manure and a control) arranged in Randomized Complete Block Design (RCBD). The plot sizes measured 6 m × 4.5 m and the main data collected was yield and labour. In the survey, the sample size was 210 farmers. Net benefits, benefit cost ratio and return to labor were used as the economic tools in data analysis. All biophysical data was subjected to analysis of variance (ANOVA). To determine factors influencing adoption of soybean, data was subjected to Cross-tabulation for categorical variables to test for association using Pearson chi-square statistic, the data was also subjected to a binary logistic regression model to predict the factors affecting adoption of soybean in the central highlands of Kenya. Results showed that there was a significant difference in soybean yield among treatments in LR 2016 and SR 2016, (P= <0.0001) and (P= <0.0033) respectively. A combination of manure plus fertilizer and tithonia plus fertilizer recorded a significant higher soybean yield than the control in both seasons. Manure plus fertilizer recorded a significantly higher net benefit and return to labour than the control in both seasons and it is the only treatment that recorded a return to labour of greater than 2.0, which is the minimum acceptable for smallholder farming activities. Out of 210 households interviewed, 41% were adopters while 59% were non-adopters. Total farm size, membership of a farmer group and attendance of training on soybean positively influenced adoption of soybean while age of household head negatively influenced adoption of soybean. The implication of these results is that farmers should be integrating organic and inorganic fertilizer in soybean farming in Embu County. Integration of manure and fertilizer should be advocated for in order to realize maximum economic benefits from soybean farming. Further, the adoption of soybean in the central Highlands of Kenya can be enhanced by targeting young household heads, household heads with bigger farm sizes, encouraging farmers to join farmer groups and increasing trainings on soybean. These findings provide a guide to the extension agents in the Ministry of Agriculture, Livestock and Fisheries (MoALF) in Embu, Meru and Tharaka Nithi Counties. This will help them in designing training manuals for farmers in regard to soybean production and increasing adoption of the crop in these Counties.
Adsorptive Ability of Banana Stalks Biochar in Greywater Remediation for Reuse: A Case of University of Embu, Kenya
(University of Embu, 2020-02) Ndung’u, Paul Waweru
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+, K+ and COD at 65.43%, 89.36% and 60.60% when compared to 58.30%, 56.96% and 49.51% for biochar 400 °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+, K+ 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.
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.
Application of water quality index to assess water quality in river chania, kiambu county, kenya
(UoEm, 2020-10-15) Kasyoka, Geofrey
Human-related activities are known to have deleterious effects on the water quality of aquatic ecosystems globally. However, there is limited information on the impact of similar perturbations in tropical regions, especially the River Chania in Kiambu County, Kenya, which is an important source of water for humans and animals and also provides habitat for a variety of flora and fauna along its length. The aim of this study was to determine the spatial and temporal variations of selected water quality parameters in seven sampling sites along a section of River Chania, to evaluate water quality of the river using Water Quality Index (WQI) and to assess the effect of socio-economic factors on water quality of the river. The study used a longitudinal study design in water sample collection. The sample collection was done between October 2018 and February 2019 to cater to the dry and wet seasons. A paired t-test (p< 0.05) was used to compare the water quality variables collected in both the wet and dry seasons across sites to see if these differed longitudinally down the river. The data were subjected to analysis of variance (ANOVA) using Statistical Analysis Software (SAS) version 9.2 and means separated using LSD at p< 0.05 confidence level. The mean values of the physico-chemical parameters were compared with the World Health Organization (WHO) water quality guidelines. The parameters used to compute WQI were nitrates, Total Dissolved Solids (TDS), potassium, sulphates, chlorides, copper, manganese, pH and total phosphates. The study revealed a decline in water quality from the most upstream site (Site 1) from excellent (WQI=23.17) to poor (WQI=>50) and very poor (WQI=>76) water quality at the two downstream sites during the wet season. On the other hand, the socio-economic factors were assessed using a survey employing cross-sectional survey design. The study observed that the education level of the respondents was a positive and significant predictor of the ability of an individual to identify water quality changes in River Chania in the last 10 years with an associated significance of 0.014. Age, household size, change in household number, gender and household income had no significant correlation with the identification of water quality changes in River Chania in the last 10 years. The study recommends that the riparian zone of River Chania, especially at downstream sites, should be protected from interference by human activities (e.g., deforestation, farming) and human interactions with the river ecosystem should be regulated for sustainable utilization, hence protect the water quality from further deterioration. Further research can be conducted to develop models for predicting water quality of the river over time.
Agro-morphological and nutritional Characterization of horned melon Accessions from selected agro-ecological Zones in kenya
(University of Embu, 2020-10-26) Owino, Marline Hanny
African horned melon (Cucumis metuliferus) is an indigenous crop belonging to the family Cucurbitaceae. The crop has been neglected despite its high potential. Therefore, to conserve the biodiversity of this crop, there is need to promote its domestication and production. However, this can only be realized if its morphology, agronomic and nutritional value is understood. The objective of this study was to determine the agromorphological performance and nutritional composition of horned melon accessions obtained from selected agro-ecological zones in Kenya. The study was conducted at the University of Embu research farm for two cropping seasons; October to January 2018 and March to June 2019. The experiment was laid out in a randomized complete block design with nineteen accessions replicated three times. The accessions were planted in experimental plots measuring 3m x 3m at a spacing of 1m by 1m. Morphological and agronomic characterization was based on modified International Plant Genetic Resource Institute (IPGRI) descriptors for melon. Data was recorded from four plants per plot per replicate. The fruit content of Fe and P were determined using atomic absorption spectrophotometry while Na and K were determined using flame photometry procedure. Vitamin C content was estimated by titrimetric method. Sugar content was determined using a brix refractometer. The qualitative and quantitative data obtained from morphological and agronomic characters were organized in a matrix and subjected to cluster analysis. A dendrogram was then constructed using unweighted pair-group method with arithmetic average. Agronomic and nutritional data was also subjected to analysis of variance using XLSTAT 2019 statistical software and means separated using Students Newmans Keuls test at 95% level of confidence. Significant differences (p<0.05) were observed in all the quantitative traits except the number of branches and main vine length. However, qualitative variations were only observed in fruit shape, rind colour and seed shape. In both seasons, the dendrogram separated into 5 supported clusters with the diversity between classes being 63.82% in the first season and 68.84% in the second season and diversity within classes being 36.18% in the first season and 31.16% in the second season. Accessions from Rongo, Wote, Siakago, Maragua, Oyugis and Meru had the highest fruit number and fruit weight for both season hence they can be more preferred by farmers and consumers. The accessions also varied significantly (p<0.05) in their nutritional composition except the Moisture Content and the Vitamin C. The composition of the mineral contents in the fruits followed the order K > P >Na >Fe .Potassium (K) content ranged from 249.52mg/100g-165.17mg/100g for Kangundo and Embu accessions respectively. Sodium (Na) ranged from 2.27mg/100g- 1.10mg/100g for Mitunguu and Siakago accessions respectively. Phosphorus (P) range was 40.49mg/100g8.76mg/100g for Migori and Machakos accessions respectively. Iron (Fe) ranged from 2.61mg/100g-0.80mg/100g for Kianjokoma and Maragua accessions respectively. The horned melon accessions tested in this study showed a high agro-morphological and nutrition variation. The study recommended the accessions from Kehancha, Embu and Siakago which recorded highest sugar content across seasons to be used by plant breedersto improve on taste which is considered to be bland by some consumers.
Agro-Morphological and Nutritional Characterization of Horned Melon Accessions from Selected Agro-Ecologicalzones in Kenya
(University of Embu, 2020-12)
African horned melon (Cucumis metuliferus) is an indigenous crop belonging to the family Cucurbitaceae. The crop has been neglected despite its high potential. Therefore, to conserve the biodiversity of this crop, there is need to promote its domestication and production. However, this can only be realized if its morphology, agronomic and nutritional value is understood. The objective of this study was to determine the agromorphological performance and nutritional composition of horned melon accessions obtained from selected agro-ecological zones in Kenya. The study was conducted at the University of Embu research farm for two cropping seasons; October to January 2018 and March to June 2019. The experiment was laid out in a randomized complete block design with nineteen accessions replicated three times. The accessions were planted in experimental plots measuring 3m x 3m at a spacing of 1m by 1m. Morphological and agronomic characterization was based on modified International Plant Genetic Resource Institute (IPGRI) descriptors for melon. Data was recorded from four plants per plot per replicate. The fruit content of Fe and P were determined using atomic absorption spectrophotometry while Na and K were determined using flame photometry procedure. Vitamin C content was estimated by titrimetric method. Sugar content was determined using a brix refractometer. The qualitative and quantitative data obtained from morphological and agronomic characters were organized in a matrix and subjected to cluster analysis. A dendrogram was then constructed using unweighted pair-group method with arithmetic average. Agronomic and nutritional data was also subjected to analysis of variance using XLSTAT 2019 statistical software and means separated using Students Newmans Keuls test at 95% level of confidence. Significant differences (p<0.05) were observed in all the quantitative traits except the number of branches and main vine length. However, qualitative variations were only observed in fruit shape, rind colour and seed shape. In both seasons, the dendrogram separated into 5 supported clusters with the diversity between classes being 63.82% in the first season and 68.84% in the second season and diversity within classes being 36.18% in the first season and 31.16% in the second season. Accessions from Rongo, Wote, Siakago, Maragua, Oyugis and Meru had the highest fruit number and fruit weight for both season hence they can be more preferred by farmers and consumers. The accessions also varied significantly
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.
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)
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.
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
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.
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.
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.
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).
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)
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

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