Browsing by Author "Majengo, Collins Otieno"

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Assessing the Long-Term Changes in Selected Meteorological Parameters over the North-Rift, Kenya: A Regional Climatology Perspective
(Hydrology, 2024-12-03) Makokha, John Wanjala; Masayi, Nelly Nambande; Barasa, Peter; Ikoha, Peters Anselemo; Konje, Martha Muthoni; Mutonyi, Jonathan; Okello, Victor Samuel; Wechuli, Alice Nambiro; Majengo, Collins Otieno; Khamala, Geoffrey Wanjala
Understanding long-term trends in climatic variables is essential for assessing climate change impacts on regional ecosystems and human livelihoods. A regional analysis of climatic variables over some domains is inevitable due to their geographical location and importance to the agricultural sector. Due to the aforementioned demands, the current study analyzes, trends in precipitation (from Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS)), and minimum and maximum temperatures (from TerraClimate) over the North-Rift region of Kenya for over thirty (30) years using satellite data. The seasonal decomposition analysis was performed for each variable to explore the trends and residual components. The findings by the current study indicate that most counties, have experienced enhance precipitation which corresponds to a declining diurnal temperature from 2019 onwards. The seasonality component reveals repeated patterns or variations occurring at steady intervals within each region's data, hence suggesting a distinct regional seasonal trend in the selected meteorological parameters over time. Basically, all counties have reported a relatively constant variability in both maximum and minimum temperatures during the study period except from 2017 onwards where significant variability in the two properties is recorded. In conclusion, the foregoing results that the selected climatic variables exhibit significant spatiotemporal and interannual variability
Characterization of Biochar Produced from Locally Available Agricultural Waste Resources for Soil Enhancement in Western Kenya
(AgroEnvironmental Sustainability, 2025-06-15) Majengo, Collins Otieno; Mutonyi, Jonathan; Kundu, Caroline Agamala; Muyekho, Francis Namasake
Valorization of agricultural waste offers a circular pathway to mitigate the intertwined crises of climate change, pollution, and biodiversity loss. Slow pyrolysis provides an effective route for transforming biomass into biochar, a porous carbonaceous material that can condition degraded soils. We quantified the physicochemical attributes of biochar produced from three contrasting residues that dominate western Kenya’s agroecosystems: coffee husk (CH), sugarcane bagasse (SB), and wood sawdust (WS). Each feedstock was air-dried for 72 h, pyrolyzed in a sealed metal kiln at 350 °C for 60 min, and cooled under an inert atmosphere. Yields averaged 37 % for CH, 32 % for SB, and 28 % for WS. Resultant biochars displayed high pH (8.4–9.2), surface area (145–275 m² g⁻¹), and cation-exchange capacity up to 92 cmol c kg⁻¹, indicating liming and nutrient-retention potential. Elemental analysis revealed increasing aromaticity (H/C < 0.35) and carbon stability with decreasing O/C ratios. Bulk density followed the order WS > SB > CH, whereas porosity exhibited the opposite pattern, reflecting structural differences in the biomasses. The correlation of ash alkalinity with calcium and magnesium contents suggested that feedstock mineralogy largely governs biochar buffering capacity. On the basis of these metrics, CH biochar emerged as the most suitable amendment for acidic Ferralsols, whereas WS biochar may serve better in sandy Arenosols requiring structural improvement. The findings supply evidence that can guide county-level policies seeking to couple waste reduction with soil fertility restoration through biochar adoption within smallholder systems.
Interaction between Biochar Sources and Phosphorus Rates on Maize Growth and Yields in Acrisols and Ferralsols of Bungoma County, Western Kenya
(International Journal of Plant & Soil Science, 2025-06-25) Majengo, Collins Otieno; Muyekho N. Francis; Kundu A. Caroline; Mutonyi Jonathan
Large proportion of phosphate fertilizer applied to acrisols and ferralsols soils reacts with aluminum (Al) and iron (Fe) to become unavailable for plant uptake. Biochar has been proposed to increase the bioavailability of phosphorus and other nutrients in the soil. The study aimed to increase maize production in low phosphorus (P) soils by evaluating the availability of phosphorus (P) in soils amended with different sources of biochar mixed with different rates of phosphorus in Acrisols and Ferralsols. Biochars were produced from three sources of feedstock: sugarcane bagasse (SB) from Butali sugar factory, wood sawdust (WS) from sawmills within Kakamega town and coffee husk (CH) from Kimukung’i coffee factory in Bungoma county. The feedstocks were pyrolysed using fabricated kilns at Kalro Kakamega. The agronomic evaluation of the fertilizers was carried out in two successive seasons of long rains and short rains of 2023 on maize crops Zea mays l.) In Kibabii site (Acrisols) and Chwele site (Ferralsols) field experiment using a split plot design with three replications. Biochar sources formed the main plots and the subplots were assigned phosphorus (P) rates. The treatments consisted of three sources of biochar (wood sawdust (WS), sugarcane bagasse (SB), coffee husk (CH) and three fertilizer use recommendation project (FURP) phosphorus (P) rates (0, 13, and 26 kg P/ha) on two soil types (Acrisols and Ferralsols). Treatments were applied simultaneously in plots measuring 2.5 m x 4.5 m in all the sites. Maize hybrid 513 at seed rate of 125 kg /ha was planted at a spacing of 75 cm x 25 cm giving a maize population of 53,333 per hectare. Nitrogen fertilizer was applied at the rate of 75kg/ha-1 Nitrogen in two split applications of 35 kg/ha-1 Nitrogen at planting and 40 kg/ha-1 Nitrogen as topdressing at mid vegetative stage per season. Phosphorus rates and biochar sources interactions on maize grain yields were significant differences (P≤0.05). Maize stover and grain yields in Kibabii and Chwele was significantly high under a combination of coffee husks biochar with 26 kg/ha-1 phosphorus treatment. The study concludes that the interaction of biochar sources and phosphorus (P) rates was highly significant in Ferralsols soils and not significant in Acrisols soils. This may be due to chelation of sesquioxides in ferralsols which enhances fixed phosphorus release thereby leading to improved crop development
Using Digital Tools to Assess Soil Variables in Selected Counties in North Rift, Kenya
(AgroEnvironmental Sustainability, 2025-03-15) Mutonyi, Jonathan; Masayi, Nelly Nambande; Majengo, Collins Otieno; Konje, Martha Muthoni; Makokha, John Wanjala
The need for techniques and instruments that enable rapid soil testing has gained attention in the face of climate change and environmental degradation. This could improve efficiency and productivity by providing real-time, high-quality, and accessible data for decision-making. This study used GPS tools to visualize, analyze, and gather essential field information and applied Near Infra-Red Spectrometry to assess soil parameters and recommend corrective action for sustainable livelihood in five Counties in North Rift Kenya. Soil reaction varied from 5.5 in Kaptega, Transnzoia, to 7.8 in Kospir, Turkana counties. Low soil pH and CEC were recorded in parts of Nandi and Transnzoia counties. Soils from the dryland ecologies in Turkana, W. Pokot, and Samburu were predominantly alkaline. Total organic Carbon was generally low in the dryland ecologies of Samburu and Turkana. Low soil fertility was generally indicated in Samburu, Turkana, and W. Pokot. This was attributable to the low organic carbon levels and low precipitation, which may have negatively influenced soil microbial activity. Sustainable farming practices such as crop rotation, mulching, mixed farming, cover cropping, and minimum/conservation tillage are recommended in areas where crop cultivation is feasible. Amelioration of soils with agricultural lime and organic matter is highly recommended in the affected areas within the agropastoral counties for improved production to guarantee food security and sustainable livelihoods