School of Agriculture & Biotechnology

A Review on Challenges and Opportunities in Management of Soils of Arid and Semi-Arid Regions of Kenya

Sat, 01 Jan 2022 00:00:00 GMT

A Review on Challenges and Opportunities in Management of Soils of Arid and Semi-Arid Regions of Kenya Nyuma, Henry Tamba; Churu, Harrison Arid and semi-arid lands occupy currently 88% of arable land mass in Kenya, a region with significant diversity of production systems and economic opportunities. However, these areas are characterised by low and erratic rainfall, hence challenges to agriculture and socioeconomic development in the wake of an increasing population and the impacts of climate change. This review seeks to identify key challenges and opportunities associated with the management of agricultural soils in these arid and semi-arid communities. Arid and semi-arid regions in Kenya are dominated by 10 soil types; Solanchaks, Solonetz, Cambisols, Arenosols, Leptosols, Vertisols, Fluvisols, Phoezems, Calcisols, and Gypsisols. Among the main soil fertility challenges in these soils are moisture stress, high erodibility, and low organic matter content, salinity, and sodium toxicity, the deficiencies of mainly N, P, Zn, and Fe, hence the vulnerability of over 14 million inhabitants to the shocks of low crop and pasture production. Moreover, the adoption of soil conservation practices remains low as existing soil fertility management technologies have been criticized for being too abstract and not providing context and site-specific solutions. Improving soil fertility and moisture levels enhances soil ecosystem functions and food and pasture production in these regions. Encouraging farmers to join soil and water conservation groups, while providing economic incentives, could potentially accelerate the adoption of soil and water practices at the farm level through pulling resources together. Future research to validate a site and context-specific integrated soil fertility improvement technologies for these soils is evitable to enhance soil functions, agricultural production and livelihood at house hold level.

Drivers of Gully Erosion and its Socio- economic and Environmental Effects in a Tropical Semi-arid Environment

Fri, 01 Mar 2024 00:00:00 GMT

Drivers of Gully Erosion and its Socio- economic and Environmental Effects in a Tropical Semi-arid Environment Churu, Harrison; Kamau, Solomon; Ng’etich, Wilson; Magiroi, Keziah; Alkamoi, Bonface; Kebeney, Syphyline; Wamalwa, Fred; Mumo, James Gully erosion is a form of severe land degradation, which is more pronounced in semi-arid and arid environments due to their vulnerable ecosystems. Establishing the causes and effects of gully erosion is therefore fundamental in policy formulation and resource allocation for up-scaling context-specific gully mitigation and rehabilitation measures. Thus, this study aimed at assessing the causes and effects of gully erosion in semi-arid region, in the North-West part of Kenya. A cross-sectional survey, field measurements, laboratory analysis, focus group discussions and key informants’ interviews were used to collect data on drivers and effects of gully erosion. Descriptive statistics and content analysis were used to analyze the data. From the findings, 60 % of the respondents reported deforestation as the main driver of gully erosion. Further, 37 and 34 % of the respondents reported surface runoff and steep slopes, respectively, as major drivers of gully erosion. Soils in the region had a high dispersion ratio, with values of between 0.3 and 0.9, making them highly erodible. About 66 and 55 % of the respondents reported that the major effects of gully erosion were reduction in arable land size and death of livestock due to fatal falls, respectively. Approximately 14 ha of arable land and 1,483,600 Mg of sediment have been lost to gully erosion at the rate of about 2,410 Mg ha-1 over a period of 45 years. The average growth rate and density of gullies in the study site stood at 154 Mg ha-1 yr-1 and 0.7 km km-2, respectively. Four people and about 100 cattle had died due to fatal falls into the deep gullies. Thus, there is an urgent need to rehabilitate existing gullies while mitigating occurrence of new gullies in the study area. This would convert existing badlands into hotspots of biodiversity.

Enhancing Sorghum Productivity in Acidic Soils Through Lime– Fertilizer Synergism: Agronomic, Economic, and Composite Performance Analysis

Sat, 01 Nov 2025 00:00:00 GMT

Enhancing Sorghum Productivity in Acidic Soils Through Lime– Fertilizer Synergism: Agronomic, Economic, and Composite Performance Analysis Rotich, Edwin Kiprono; Oloo, Peter Kisinyo; Opala, Peter Asbon; Odundo, Gudu Samwel Sorghum productivity in Western Kenya is severely constrained by acidic soils, particularly Ferralsols and Acrisols prone to aluminum toxicity and phosphorus fixation. This study assessed the performance of limeintegrated fertilizer treatments under smallholder conditions using a randomized complete block design across three sites. Sorghum grain yield (SGY), agronomic efficiency (AE), nutrient uptake efficiency (NUE), and gross margin (GM) were measured alongside the formulation of a composite Performance Index (PI) designed to simulate both physiological and economic effects. We developed a composite Performance Index to integrate agronomic and economic outcomes, enabling balanced evaluation of lime–fertilizer strategies across acid-prone sites. The PI incorporated weighting scenarios reflecting equal and smallholder-adjusted preferences. Results showed that lime enhanced AE (up to 55%), NUE (up to 34.6%), and SGY ≥ 1.8 t ha⁻¹ across sites, with intermediate fertilizer rates yielding superior performance. GM exceeding $450 ha⁻¹ and benefit–cost ratios over 2.0, demonstrating strong economic viability, Lime + N37.5P13 consistently outperformed other treatments, offering agronomic–economic balance and robust PI ranking across sensitivity models. Radar and contour plots identified optimal combinations and revealed trade-offs between efficiency and yield. These findings support lime as a foundational input rather than a supplemental one, and advocate for context-driven ISFM strategies aligned with smallholder realities. The PI framework offers a flexible and empirically grounded tool for sustainable intensification decisions in acid soil systems.

EVALUATION OF YELLOW MAIZE (Zea mays L) INBRED LINES’ PERFORMANCE AND COMBINING ABILITY USING LINE BY TESTER ANALYSIS IN WESTERN KENYA

Wed, 01 Jan 2025 00:00:00 GMT

EVALUATION OF YELLOW MAIZE (Zea mays L) INBRED LINES’ PERFORMANCE AND COMBINING ABILITY USING LINE BY TESTER ANALYSIS IN WESTERN KENYA SHIUNDU, DANIEL WAMACHE There is need to continuously develop and deploy highly adaptable and productive maize hybrid varieties for use by farmers against the greatly dynamic biotic and abiotic stresses that face production of this crop in the country. The objective of this study was to estimate the hybrid performance and the combining abilities of yellow maize inbred lines and their testcrosses for grain yield and yield-related traits across three locations. Sixty-five yellow maize inbred lines were crossed to two-line testers; Cimmyt maize lines (CML) 486 (Tester A) and 451 (Tester B) using a line by tester design. Resultant a hundred and thirty F1 testcrosses with three check varieties were evaluated on three locations in western Kenya using a 7×19 alpha lattice with two replications. Data on grain yield and yield-related traits was collected. Means and variance components on hybrid performance were computed in META-R version VI and combining ability analysis done using Restricted maximum likelihood (REML). Grain yield means ranged between 12.4T/Ha and 2.8T/Ha with testcross L45×TA producing the highest grain yield mean across sites. High heritability (>60%) was recorded for grain yield and other yield-related traits except for northern leaf blight which was moderate. All yield-related traits in the study except northern leaf blight had significant phenotypic correlations with grain yield. Ear height had the highest positive correlation at 0.7(P<0.001). Across sites Analysis of Variance (ANOVA) revealed highly significant (p<0.001) mean squares for sites, hybrids, line general combining ability (GCA) line GCA by site, hybrid by site, specific combining ability (SCA) as well as SCA by site. L45 had the highest positive GCA for grain yield at 2.7 (p<0.05). L23, L65, L29 and L25 crossed with tester A showed positive significant SCA estimates for grain yield whereas L36×TA had a negative but significant SCA for grain yield at -1.9 (p<0.05). Based on SCA estimates with the testers, the inbred lines grouped into two heterotic groups A and B with 60% and 38.5% of the inbred lines respectively. L45 and other 33 lines that had positive GCA for grain yield could be exploited in the development of high yielding yellow maize hybrids. Testcrosses L45xTA, L47xTA and L35xTB showing equivalent or better performance to the mean of the checks have potential for further evaluation and consideration for release as adaptable and stable superior yielding yellow maize single cross hybrids.

Influence of Planting Materials and Land tenure system on Mango Production in Endo Ward, Elgeyo Marakwet County, Kenya

Sat, 01 Apr 2023 00:00:00 GMT

Influence of Planting Materials and Land tenure system on Mango Production in Endo Ward, Elgeyo Marakwet County, Kenya Kipchumba, Abraham; Odwori, Paul O.; Kebeney, Syphyline Mango (Mangifera indica L.) is Kenya’s third most important fruit in terms of acreage and total production. Mango is grown in Coastal, Eastern, and Central and in Rift valley dominantly in Kerio Valley belt due to favourable environmental conditions. Recent research, however, has reported a decline in mango production in Endo Ward. Therefore, the objective of this study was to determine the factors that affect smallholder mango production in Endo Ward, Elgeyo Marakwet County. A survey was carried out in which a sample population of 281 farmers were chosen from a target population of 937 farmers. A simple random sampling technique was used in selecting the locations and the respondents. Primary data was obtained using questionnaires and interview on key informants. Data collected was analysed using descriptive and inferential statistics. The results indicated that 42.96% of planting materials are obtained by farmers from local private nurseries while 23.47% get from Kerio Valley Development Authority (KVDA) nurseries. Thus, the high cost deterred some farmers from accessing mango planting materials easily hence decline in production. Results also showed that the land tenure system was such that 89.53% of the farmers owned land communally while only 10.47 % owned individual land. This lack of property rights on Land resource did not motivate farmers sufficiently enough to invest optimally in mango production. This study recommends that there is need to assist the farmers to access affordably planting materials and grant tittle deeds to farmers to motivate optimum individual effort.

INFLUENCE OF ENVIRONMENT AND ITS INTERACTION EFFECTSON NEW POTATO [(Solanum tuberosum (L.)] MUTANT LINES

Sun, 01 Jun 2025 00:00:00 GMT

INFLUENCE OF ENVIRONMENT AND ITS INTERACTION EFFECTSON NEW POTATO [(Solanum tuberosum (L.)] MUTANT LINES Muasya, Mutati; Kinyua, Miriam; Chepkoech, Emmy

Soil-Plant Nutrient Dynamics and Fertilizer Use Efficiency in Maize & Desmodium Cropping System

Wed, 01 Oct 2025 00:00:00 GMT

Soil-Plant Nutrient Dynamics and Fertilizer Use Efficiency in Maize & Desmodium Cropping System Odera, Irine Akinyi; Otinga, Abigael Nekesa; Njoroge, Ruth; Mutua, Scholastica Soil fertility decline and inefficient nutrient use remain major challenges limiting maize productivity in the arid and semi-arid lands (ASALs) of Kenya. This study evaluated the effects of integrating farmyard manure (FYM) with inorganic fertilizers on soil properties, nutrient uptake, yield performance, and efficiency indices in sole maize sole desmodium and maize-desmodium intercrop systems under field conditions in Keiyo North. The experiment consisted of six fertilizer substitution ratios (0-0, 25-75, 50-50, 75-25, 100-0, and 0-100% farmyard manure-inorganic N equivalence) arranged in a randomized complete block design with four replications. Soil chemical parameters (NH₄⁺, NO₃⁻, pH, N, P, and C), plant nutrient uptake, and agronomic and recovery efficiencies were assessed. Results showed that combined farmyard manure – inorganic treatments, particularly 25-75 and 75-25, significantly improved soil nutrient status, enhanced N and P uptake, and increased maize and desmodium yields compared to sole applications. Farmyard manure -rich combinations improved moisture retention and microbial activity, sustaining nutrient release, while inorganic fertilizers ensured rapid early growth. Intercropping enhanced biological nitrogen fixation and nutrient recovery, leading to higher agronomic efficiency and resilience under moisture-limited conditions. The findings underscore that partial substitution of inorganic fertilizers with farmyard manure, coupled with maize-desmodium intercropping, offers a sustainable pathway to enhance soil fertility, nutrient use efficiency, and productivity in arid and semi-arid lands farming systems.

Agroforestry adoption and its influence on soil quality under smallholder maize production systems in western Kenya

Tue, 01 Apr 2025 00:00:00 GMT

Agroforestry adoption and its influence on soil quality under smallholder maize production systems in western Kenya Nyum, Henry Tamba; Njoroge, Ruth; Otinga, Abigael Nekesa Agroforestry, a sustainable land use practice, was introduced in western Kenya in the early 1990s as a soil fertility replenishment strategy. Since then, the effect of the practice on soil quality has seldom been evidenced. A study was conducted to assess the impact of agroforestry adoption on soil quality under smallholder maize systems in the region. Soil samples were collected from two land use practices: agroforestry adoption (90) and non-agroforestry adoption (30) at 0–30cm depth from two locations (Busia and Kakamega counties). Results showed variations in soil characteristics between the study locations. Soils in Kakamega contained higher concentrations of soil organic carbon (SOC), exchangeable cations, and micronutrients. On average, agroforestry adoption significantly (P≤0.05) improved soil physicochemical properties. Under agroforestry adoption, bulk density (BD) reduced by 21% (from 1.4 to1.1g cm-3), while (SOC) increased by 75% (0.8–1.4%), P by 80% (3.0–5.4mg kg-1), exchangeable K by 256% (0.3–8.0 cmol kg-1), Ca by 100% (1.0–2.0 cmol kg-1), S by 50% (0.2–0.3mg kg-1), and Cu by 18% (2.8–3.3mg kg-1). Agroforestry adoption significantly increased K and Cu levels above the critical thresholds of 0.4 cmol kg-1 and 1.0mg kg-1, respectively, at both locations. Sesbania sesban and Leucaena leucocephala influenced soil BD, pH and P (4.3.-7.0mg kg -1), exchangeable K (0.4–0.7 cmol kg-1), Mg (0.1–0.2 cmol kg-1), and Mn (13.5–25.2mg kg-1) at both locations, while Calliandra calothyrsus significantly increased SOC in Kakamega only. These findings highlight the significance of agroforestry in soil fertility management. Furthermore, Sesbania proved to be effective in enhancing the characteristics of soils at both sites, hence, the need for its inclusion in agroforestry extension messages. Further studies are needed to understand nutrient release mechanisms from agroforestry biomass and their influence on soil characteristics and maize yield in smallholder farming systems.

Nutrient dynamics and decomposition of agroforestry litter in acidic soils of Uasin Gishu County, Kenya

Tue, 01 Apr 2025 00:00:00 GMT

Nutrient dynamics and decomposition of agroforestry litter in acidic soils of Uasin Gishu County, Kenya Nyuma, Henry; Njoroge, Ruth; Otinga, Abigael Multiple forms of biomass, including litter, herbaceous, and woody biomass emanating from agroforestry systems, have numerous environmental and socioeconomic benefits, including improved soil health, biodiversity, carbon sequestration, and diversified income. These benefits are crucial to sustainable production. Despite agroforestry's significant contribution to sustainable food production, less attention is given to litter mass decomposition and its mechanisms of nutrient release and cycling. A study to assess the influence of agroforestry litter quality on decomposition and nutrient release in acidic soils of Uasin Gishu County, Kenya, was conducted at the University of Eldoret. The hypothesis was that the litter type of three agroforestry species - Gliricidia, Leucaena, and Sesbania - affects the rate of decomposition, nutrient release pattern, and the chemical characteristics of acidic soils. Results from the study revealed a significant (P≤0.05) influence of agroforestry litter type and initial litter quality on the rate of decomposition and nutrient dynamics in the order of Sesbania > Gliricidia > Leucaena. Sesbania showed superior litter quality, recording the highest OC (48.1%), N (25.9 g kg-1 ), and Cu (0.35 ppm), and the lowest concentration of lignin (18.0%), cellulose (24.0%), and the lowest C:N, L:N, L:PP, L:P:N, and L:N:P ratios, hence the highest rate of decomposition (k=0.04). Nutrient release was in the order of Fe=Cu>K>Ca>Mg=Mn>N=Zn>P for Gliricidia, Ca>Cu>K=Mn>P>Zn>N for Leucaena, and Ca>Cu>Mn=Mg>P=K>N>Zn for Sesbania. Although there were no significant differences in nutrients released from the three litter types, Sesbania recorded the fastest release of N, P, Cu, and Mn, contributing about 3.2% SOC, 25.5 kg P ha-1 , and 11.4 kg K ha-1 to the soil. Mean soil enrichment (ER=1.1, 1.5, and 2.5) for SOC, P, and K, respectively, indicates the potential of agroforestry litter mass of Sesbania sesban in nutrient cycling. These findings provide insights into the crucial role of agroforestry litter in the cycling of macro and micronutrients, hence enhancing soil ecosystems and sustainable production. However, further studies involving different litter types in multiple agroecological zones are needed to assess the impacts of other environmental factors on nutrient release mechanisms in acid soils.

BIOASSAY AND RESPONSE OF PYRETHRUM (Chrysanthemum cinareriifolium) GENOTYPES TO PATHOGENIC FUNGI IN KENYA

Wed, 01 Jan 2025 00:00:00 GMT

BIOASSAY AND RESPONSE OF PYRETHRUM (Chrysanthemum cinareriifolium) GENOTYPES TO PATHOGENIC FUNGI IN KENYA RUTO, CHEPKEMOI EMMY Fungal pathogens are a major production constraint to quantity and quality of pyrethrin in Kenya and other parts of the world. Pyrethrin is a natural insecticide that is cheap, environmentally friendly, acts with celerity, less harmful to both animals and humans and also can be used against a wide range of insects and because of the above importance of pyrethrum and the problem of fungal diseases as a constraint to higher production of the crop, this study was carried out with the following objectives; 1) To assess the morphological diversity and frequency of isolation of the major fungal pathogens affecting pyrethrum production in Kenya, 2) To assess the pathogenicity of identified fungal isolates and response of selected genotypes under greenhouse conditions and 3) To determine the efficacy of selected control agents in management of identified fungal pathogens in vitro and therefore, A field visit to major pyrethrum growing zone Nakuru county, was done and infected plant parts with symptoms of fungal infection were sampled and taken to laboratory for analysis. Isolation and identification was done and after identification pathogens with higher isolation frequencies were tested for their pathogenicity and virulence on five pyrethrum genotypes Clone 1 - 4 and P4 in an experiment set in split plot arrangement in CRD with genotypes as main plots and isolates as subplots replicated three times. Data on incidence and severity were scored after inoculation at an interval of 14 days using severity scales. Most virulent pathogens were further selected and taken to the laboratory for testing inhibitory efficacies of selected control agents where a split plot arrangement in CRD was set with isolates as main plots and control agents as sub plots replicated thrice. Agar dilution method and dual culture method were used to test control agents and data on mycelial growth inhibition were scored. Results indicate that there was diversity in fungal pathogens isolated from plants showing symptoms of bud disease, pyrethrum wilt and crown rot disease. There was a significant difference in the pathogenicity and response of selected isolates as p <0.05. All the isolates tested were pathogenic and Clone 4 was more tolerant to most fungi. Botanicals showed promising results as garlic performed well like Carbendazim in the in vitro reactions with the test fungi. Selected Trichoderma species displayed antifungal properties against all the test fungi. These results indicate that fungal pathogens are still a problem in farmers’ fields and available genotypes have varied levels of tolerance which can be exploited in the breeding programs in order to achieve a long-lasting solution to fungal diseases.