Journal Articles

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

2022-01-01T00:00:00Z

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

2024-03-01T00:00:00Z

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

2025-11-01T00:00:00Z

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.

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

2025-10-01T00:00:00Z

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.

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

2025-04-01T00:00:00Z

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.

Response of Rice Beans (Vigna umbellata) to Different Phosphate Fertilizer Rates, Sources and Cropping Systems Established in Western Kenya

2025-09-01T00:00:00Z

Response of Rice Beans (Vigna umbellata) to Different Phosphate Fertilizer Rates, Sources and Cropping Systems Established in Western Kenya Migaya, Erick Omondi; Njoroge, Ruth; Otinga, Abigael N.; Kisinyo, Peter Oloo Rice bean despite being an underutilized crop is a multipurpose legume crop with a potential of improving food security in western Kenya. Acidic soils with low phosphate and organic carbon levels limit its production. We investigated effects of four phosphate fertilizer levels and cropping systems on soils, agronomy and yield components of rice beans in Kaimosi Friends University College (KAFUCO), Rongo University and Siaya Agricultural Training Centre (ATC) farms in Vihiga, Migori, and Siaya Counties in western Kenya in the short rains of 2020 and long rains of 2021. The experiment consisted of twelve treatments replicated three times per site in a split-plot in a randomized complete block design (RCBD). The main plots comprised of three cropping systems(monocrop, conventional and MBILI (Managing Beneficial Interactions in Legume Intercrops)) while the subplots were made up of four phosphate fertilizer levels (without fertilizer (control), inorganic fertilizer (26P+22N kg ha-1 ), pure organic (5P+22N kg ha-1 ) and combined organic and inorganic fertilizers at half rates (15.5P+22N kg ha-1 ). Soil analysis demonstrated that the soils had low P and % organic carbon in all the sites. There were no significant differences in Olsen P at p = .05 in all the sites. In Kaimosi, the average number of pods produced per plant was highest in the mono cropping systems (90) for treatments with mixed organic and inorganic phosphate fertilizers. Treatments with required phosphate fertilizers had the least number of days to flowering (about 75). However, days to 75% flowering in both seasons showed no significant differences in Kaimosi University and Siaya ATC farms with significant differences exhibited in Rongo University farm between the cropping systems at p= .05. The highest average rice beans yields were recorded in Rongo university farm (1.8 ton ha-1 ) for the treatments with mixed organic and inorganic fertilizers in the mono cropping systems. The phosphorus agronomic efficiency was highest in treatments with pure organic matter. The partial factor productivity of phosphorus was highest in the mono cropping systems. There were significant differences in harvest indices, partial factor productivity and phosphorus agronomic efficiency in all the three sites 1.8 ton ha-1 . The study therefore has recommended that phosphate fertilizers are important in the rice beans production for improved yields to be realized.

Aerobic Composting of Antibioticcontaminated Manure: Degradation Processes and Their Effects on Greenhouse Gas Emissions

2025-07-01T00:00:00Z

Aerobic Composting of Antibioticcontaminated Manure: Degradation Processes and Their Effects on Greenhouse Gas Emissions Arusey, Chebet; Kebeney, Syphyline; Ngetich, Wilson Introduction:The widespread use of antibiotics in livestock production results in significant excretion of unmetabolized residues in manure, posing risks such as the emergence of antibiotic-resistant bacteria(ARB), antibiotic resistance genes (ARGs), and elevated greenhouse gas (GHG) emissions. Composting has emerged as a promising strategy to mitigate these risks.Aims:This review formed a foundation for manure incubation regarding the fate and effects of three antibiotics –Tylosin, Enrofloxacin, and Oxytetracycline on manure GHG ammonia (NH3)missions, and fertilizer quality. It synthesizes existing evidence on antibiotic degradation during composting, highlighting the influence of composting conditions,additives,and their effects on greenhouse gas emissions. Methods:A comprehensive literature search was done following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Systematic searches were performed in threedatabases: Web of Science, PubMed, and Scopus, for original articles using a combination of Query terms and an established inclusion and exclusion criteria.Results:The 66 studies that met the criteria were from 21 countries. Outcomes show that composting conditions (temperature, aeration, moisture), additive types (e.g., biochar, zeolite), and microbial inoculants play critical roles in antibiotic degradation and GHG emission dynamics. Thermophilic composting promotes degradation of labile antibiotics, while persistent compounds may require extended treatment. Overall, the review identified that physicochemical and microbial processes drive antibiotic degradation, suggesting that specific additives enhance these pathways, influencing GHG emissions. Conclusion:Composting is a viable strategy for managing antibiotic-laden manure and calls for further research into advanced treatments, bioaugmentation, and integration with other waste management technologies.

Arbuscular Mycorrhizal Fungi Enhance P Uptake and Use Efficiency of Wheat (Triticum aestivum L.) in Ferralsols: A Study at Uasin Gishu County, Kenya

2025-01-01T00:00:00Z

Arbuscular Mycorrhizal Fungi Enhance P Uptake and Use Efficiency of Wheat (Triticum aestivum L.) in Ferralsols: A Study at Uasin Gishu County, Kenya Njoki, Anne; Njoroge, Ruth; Ndungu-Magiroi, Keziah; Kamau, Solomon; Churu, Harrison Deficiency of macro and micronutrients is a major challenge to sustainable wheat production. Integrating biostimulants such as Arbuscular Mycorrhizal Fungi (AMF) and inorganic fertilisers has been shown to enhance wheat production by optimising their mutual benefits. However, integration of AMF and micronutrients has not been prioritised, especially in low-input systems. Thus, a twoseason field study was conducted at the University of Eldoret farm, Uasin Gishu County, Kenya, to evaluate the integrated effect of AMF concoctions with phosphorus (P) and copper (Cu) fertilisers on nutrient uptake, use efficiency, and productivity in wheat. The different levels of P, Cu, and AMF were combined. The treatments were laid out in a Randomised Complete Block Design (RCBD) and replicated three times. Two levels of AMF (0 and 60 L ha-1 ) were applied with three levels of P: 0 kg, 8.8 kg, and 17.6 kg ha-1 , and three levels of Cu: 0 kg, 5 kg, and 10 kg ha-1 . Generalised linear models (GLM) were used to test the effects of AMF and fertiliser type on soil chemical properties and crop performance indices. Two- and three-way interactions between the three factors were also tested. Results show that AMF did not have significant impact on soil available P, while available Cu increased by 32% - 40% compared to the control. AMF also enhanced P and Cu uptake by 27 - 30% and 24 - 38%, respectively. Furthermore, AMF increased P and Cu use efficiency by about 15 - 31% and 18 - 35% above the plots without AMF, respectively. Co-application of P at 8.8 kg ha-1 and 60 L AMF ha-1 recorded the highest wheat grain yield of 2.84 and 4.72 Mg ha-1 during the 2018 and 2019 long rain seasons, respectively. The study shows that the use of AMF could play a significant role in reducing the amount of inorganic P fertilisers while increasing wheat grain yield. This study recommends co-application of 60 L AMF and 8.8 kg P ha-1 for improving P nutrition and grain yield in wheat.

Findings from a survey in Western Kenya to determine the soil fertility replenishment technologies adoption rates

2019-01-01T00:00:00Z

Findings from a survey in Western Kenya to determine the soil fertility replenishment technologies adoption rates Mong’are, Peris Oroko; et. al... A survey on adoption levels of the existing soil nitrogen replenishing technologies amongst farmers in three counties in western Kenya was carried out in June 2011. Three farmer associations were Angurai Farmers Development Project (AFDEP), Bungoma Small-Scale Farmers Forum (BUSSFFO) and Mwangaza Farmer Group (MFAGRO). During the survey 223 farmers were interviewed with roughly a half of the households surveyed being members of farmer associations (FAs) and the other half being non-members, who acted as the control. Stratified random sampling technique was used. A repeated measures Analysis of Variance (RM – ANOVA) showed that various soil nitrogen replenishment technologies were adopted to various degrees, F (4.39, 855.43) =23.36, p<.001). The findings of this study indicated that the available technologies most extensively used in the study area were the use of inorganic fertilisers (DAP), planting of improved legumes processing, Lab lab, Push Pull, and Super 2 Package. In second place, were technologies such as seed inoculation, foliar feed use, top dressing fertiliser (CAN) and use of improved legumes. The least used technologies were found to be Ua Kayongo (IR seed), MBILI intercropping, fortified compost, and use of Farm yard manure and liming. The results also indicated that generally, adoption of technologies was higher amongst farmer association members compared with non-members regardless of the county. Bungoma County had significantly highest level of technology adoption level compared to both Busia and Vihiga. Adoption of soil technologies was also found to be positively correlated with farmers’ educational level but inversely related with their age.

The Role of Sorghum Legume Intercroping System in Improving Soil Productivity on Small Holder Farmers in Western Kenya

2022-01-01T00:00:00Z

The Role of Sorghum Legume Intercroping System in Improving Soil Productivity on Small Holder Farmers in Western Kenya Barasa, Josephine Declining crops yield in the smallholder farmers cropping systems of sub-Saharan African (SSA) present the need to develop more sustainable production systems. Depletion of essential plant nutrients from the soils have been cited as the main contributing factors due to continues cultivation of cereal crops without application of organic/ inorganic fertilizers. Field experiments to evaluate effect of phosphorus (P) fertilizers, organic and integration of legumes in sorghum cropping systems on soil, available nitrogen (N) and P, were conducted in Busia County of Kenya during the short (SRS) and long rain seasons (LRS) of 2016 and LRS of 2017 respectively. The experiments comprised either soybean, common bean groundnut or sesame grown with sorghum. The design was a split plot in a randomized complete block design. Main plots were fertilizer inputs; Mavuno, FYM or their combination. Subplots comprised of the legume intercrops mentioned above. Application of Mavuno, FYM or their combination resulted in significantly higher legume, sesame crop yields above the control in the second season. Legume crops due to their N-fixation, litter fall and mineralization made availability of P and N. possible. Application of Mavuno, FYM or their combination gave comparable results with respect to the intercrop yields. Since FYM and (Mavuno+FYM) is cheaper than Mavuno, growing either soybean, common bean groundnut or sesame intercropping system with sorghum with application of the above is recommended for improved legume grain yields and soil fertility improvement.