Agronomy

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A Soil Tool Kit to Evaluate Soil Properties and Monitor Soil Health Changes in Smallholder Farming Contexts
(Elsevier Publishing Company, 2020-10-15) Nyamasoka-Magonziwa Blessing; Vanek Steven J.; Ojiem John O.; Fonte Steven J.
Smallholder farmers often face challenges in managing soil fertility due to limited inputs and high spatial variability on their farms. While improved knowledge of soil constraints could help them manage limited resources more effectively, formal soil analyses are typically out of reach due to high costs of testing and transport associated with regional analytical laboratories. To address these challenges, we assembled a tool kit that uses minimal reagents and low-cost equipment to provide in-field quantitative data that are comparable to formal laboratory methods. We validated our tool kit measurements against standard analyses conducted at national laboratories on soils collected from 36 smallholder farms in Kenya and 115 farms in Peru. Additionally, in Kenya, we evaluated two legume treatments, involving the incorporation of residues from: 1) Lablab purpureus (lablab), versus 2) Phaseolus vulgaris (common bean). The tool kit measurements that were considered include important indicators of soil health (such as permanganate oxidizable carbon (POXC), available P, pH, particulate organic matter (POM), and aggregate stability) that can influence crop yields and multiple soil functions. POXC and pH measured with the tool kit from Kenyan soils were highly correlated to those measured by a standard laboratory (R2 = 0.77; R2 = 0.56; respectively). The tool kit and standard laboratory available P were less well correlated, but also showed a highly significant positive relationship (R2 = 0.30). Similar patterns were noted for POXC, pH and available P measured in Peruvian soils (R2 = 0.75; R2 = 0.75; R2 = 0.35; respectively). Importantly, the tool kit and standard lab analyses also displayed similar abilities to predict maize grain yield in Kenya. When used to detect soil impacts of incorporating P. vulgaris versus L. purpureus, only POM differed significantly between the two legume treatments, although L. purpureus was slightly higher for most of the beneficial soil health properties. Our findings suggest that the tool kit methods proposed here have broad applicability to smallholder farms for explaining variability in crop yields, assessing soil contexts, and quantifying management-induced changes in soil health.
Adoption, constraints and economic returns of paddy rice under the system of rice intensification in Mwea, Kenya
(Elsevier, 2013-11-01) Ndiiri, J. A.; Mati, B. M.; Home, P. G.; Odongo, B.; Uphoff, N.
A detailed farm survey was conducted in Mwea Irrigation Scheme, Kenya during the 2010/2011 and 2011/2012 main growing seasons to assess the adoption and to quantify the net income advantages of using system of rice intensification (SRI) management over farmer practices (FP) for rice cultivation. Data were collected through questionnaires and structured interviews with farmers who were practicing both SRI and FP methods of rice production on their farms. Under FP, three seedlings aged 28 days are transplanted in respective hills at random spacing. The fields are then flooded with water throughout the growing period. For SRI practice, factors considered as essential were transplanting only one seedling per hill aged 8–15 days with spacing of at least 20cm by 20cm; weeding the crop at least three times at intervals of ten days; and intermittently irrigating the fields. The contributions of using organic manure for fertilization and soil-aeration weed control methods were not considerations in this study since the availability of organic materials and mechanical push-weeders were challenges at the time of study. A total of 40 farmers in 10 units out of the 50 SRI farmers from 18 units of the irrigation scheme were sampled. Benefit–cost relationships were estimated using tabular analysis of all the variable costs and income from production using the survey data. On average, yield under SRI management increased by 1.6t/ha (33%), with seed requirements reduced by 87% and, water savings of 28%. SRI required 9% more labor than FP on average, but this factor of production showed great variability; in three Mwea units, labor costs were reduced by an average of 13%. SRI required 30% more labor for weeding than FP in the first season, but this was reduced to 15% in the second season when push-weeders became available. The results showed SRI giving a higher benefit–cost ratio of 1.76 and 1.88 in the first and second seasons, respectively, compared to 1.3 and 1.35 for FP. The results indicated that SRI practices of planting younger seedlings, with wider spacing and intermittent irrigation, lead to increased paddy rice yields with concomitant rise in the income accruing to farmers. Possibly further increases in net benefit could come with enhanced availability of mechanical weeders and using organic material for fertilization. Up-scaling of SRI in Mwea can be expected to help achieve greater national and household food security
Aflatoxin Contamination of Maize and Groundnut in Burundi: Distribution of Contamination, Identification of Causal Agents and Potential Biocontrol Genotypes of Aspergillus Flavus
(Frontiers, 2023) Nsabiyumva Gedeon; Muteg Charity K; Wagacha John M; Mohamed Asha B; Njeru Nancy K; Niyuhire Marie C; Joseph Atehnkeng; Njukwe Emmanuel; Cotty Peter J; OrtegaBeltran Alejandro; Bandyopadhyay Ranajit
Aflatoxin contamination of the staples maize and groundnut is a concern for health and economic impacts across sub-Saharan Africa. The current study (i) determined aflatoxin levels in maize and groundnut collected at harvest in Burundi, (ii) characterized populations of Aspergillus section Flavi associated with the two crops, and (iii) assessed aflatoxin-producing potentials among the recovered fungi. A total of 120 groundnut and 380 maize samples were collected at harvest from eight and 16 provinces, respectively. Most of the groundnut (93%) and maize (87%) contained aflatoxin below the European Union threshold, 4 μg/kg. Morphological characterization of the recovered Aspergillus section Flavi fungi revealed that the L-morphotype of A. flavus was the predominant species. Aflatoxin production potentials of the L-morphotype isolates were evaluated in maize fermentations. Some isolates produced over 137,000 μg/kg aflatoxin B1. Thus, despite the relatively low aflatoxin levels at harvest, the association of both crops with highly toxigenic fungi poses significant risk of post-harvest aflatoxin contamination and suggests measures to mitigate aflatoxin contamination in Burundi should be developed. Over 55% of the L-morphotype A. flavus did not produce aflatoxins. These atoxigenic L-morphotype fungi were characterized using molecular markers. Several atoxigenic genotypes were detected across the country and could be used as biocontrol agents. The results from the current study hold promise for developing aflatoxin management strategies centered on biocontrol for use in Burundi to reduce aflatoxin contamination throughout the value chain.
Aflatoxin Contamination of Maize and Groundnut in Burundi: Distribution of Contamination, Identification of Causal Agents and Potential Biocontrol Genotypes of Aspergillus Flavus
(Frontier, 2023) Nsabiyumva Gedeon; Mutegi Charity K; Wagacha John M; Mohamed Asha B; Njeru Nancy K; Ndayihanzamaso Privat; Niyuhire Marie C; Joseph Atehnkeng; Njukwe Emmanuel; Callicott Kenneth A; Cotty Peter J; Ortega-Beltran Alejandro; Bandyopadhyay Ranajit
Aflatoxin contamination of the staples maize and groundnut is a concern for health and economic impacts across sub-Saharan Africa. The current study (i) determined aflatoxin levels in maize and groundnut collected at harvest in Burundi, (ii) characterized populations of Aspergillus section Flavi associated with the two crops, and (iii) assessed aflatoxin-producing potentials among the recovered fungi. A total of 120 groundnut and 380 maize samples were collected at harvest from eight and 16 provinces, respectively. Most of the groundnut (93%) and maize (87%) contained aflatoxin below the European Union threshold, 4 μg/kg. Morphological characterization of the recovered Aspergillus section Flavi fungi revealed that the L-morphotype of A. flavus was the predominant species. Aflatoxin production potentials of the L-morphotype isolates were evaluated in maize fermentations. Some isolates produced over 137,000 μg/kg aflatoxin B1. Thus, despite the relatively low aflatoxin levels at harvest, the association of both crops with highly toxigenic fungi poses significant risk of post-harvest aflatoxin contamination and suggests measures to mitigate aflatoxin contamination in Burundi should be developed. Over 55% of the L-morphotype A. flavus did not produce aflatoxins. These atoxigenic L-morphotype fungi were characterized using molecular markers. Several atoxigenic genotypes were detected across the country and could be used as biocontrol agents. The results from the current study hold promise for developing aflatoxin management strategies centered on biocontrol for use in Burundi to reduce aflatoxin contamination throughout the value chain.
Agricultural Climate Atlas for Kajiado and Kiambu Counties, Kenya
(springer, 2021-11-04) Matsaba, Emmanuel Ochola; van Selm, Merlijn; Wesonga, John Mwibanda; Goosen, Hasse; Coninx, Ingrid; Koomen, Irene
Crop production in Kenya takes place mostly under rain-fed conditions, with weather fluctuations having a high impact on productivity. Significant changes in the climate are expected between now and the end of the century, while many smallholder farmers are ill-equipped to cope with climate-related risks. These challenges are exacerbated by the fact that agricultural investment decisions and policy aspects for systemic adaptation require long-term planning. Therefore, there is a need to know what kind of climate change to expect. A climate atlas was developed as an interactive and user-oriented tool to provide a first insight into the projected impact of climate change on the agricultural sector in Kajiado and Kiambu Counties in Kenya. The information is provided on a web-based platform and is easy to access by farmers, farmer organizations, agri-food businesses, policymakers, and investors for climate decisions and planning. The information results from downscaling global climate change models to the Kenyan context, combined with the local agricultural sector’s vulnerability information. Via graphs and interactive maps, projected climate impacts are presented. The climate atlas also comprises an expert tool that allows exploration of climate impacts for a tailored situation to evaluate particular crops and/or varieties’ suitability in a specific location. The climate atlas is critical for starting a dialogue on the climate challenges that affect the two counties. Results can be translated into investment portfolios for climate-proofing agribusinesses and accelerating investments due to the potential to mitigate climate-related risks.
Assessing Sensory Characteristics and Consumer Preference of Legume-Cereal-Root Based Porridges in Nandi County
(Journal of Food Quality, 2019-06-18) Gitau Peninah W.; Kunyanga Catherine N.; Abong’ George O.; Ojiem John O.; Muthomi James W.
Previously, porridge has been cereal based, consumed as a beverage or weaning food. Malnutrition among children has necessitated inclusion of legumes and roots in an e ort to boost nutrient density. erefore, the current study aimed at identifying the most acceptable porridge based on di erent food ingredient combination. Composite porridge our included legumes (soybean, groundnut, and lablab), cereals ( nger millet, sorghum, maize, and wheat), pseudocereals (pumpkin seed, buckwheat, and amaranth seed), and roots (cassava and arrowroot). New composite porridge ours were formulated using Nutrisurvey linear programming software. Di erent composite ours formulated to target either school-going children or a family setup were subjected to sensory analysis and the consumer preference test. Eight new formulations were developed. Buckwheat, wheat, and arrowroot were eliminated, maize and lablab content (%) were reduced, and cassava and nger were increased in the new formulations. A total of 149 participants composed of men (30.9%) and women (69.1%) aged between 11 and >60 yrs were interviewed. Newly formulated porridges were more preferred to the previous porridge formulations on color (40–54.2%), smell (40–52.4%), taste (41.5–47.5%), texture (58.3%), viscosity (35.4–45.8%), and overall acceptability (35–54.2%). e most cited reason for liking or disliking a particular porridge was taste (38.9%) and texture (32.2%), respectively. However, all the sensory attributes positively correlated with overall acceptability. Increased nger millet and cassava proportions in the newly formulated composite porridge our highly in uenced their high acceptability. us, consumer acceptability of new products is key for their adoption.
Biomass Yield and Quality of Fodder from Selected Varieties Of Lablab (Lablab Purpureus L) In Nandi South Sub-County of Kenya
(Online Journal of Animal and Feed Research, 2021) Wangila Anthony Juma; Gachuiri Charles Karuku; Muthomi James Wanjohi; Ojiem John Okeyo
Low quality feeds is the main challenge ailing livestock production among the small-scale farmers in the tropics. Cheaper sources of alternative high quality fodder supplements are needed to improve livestock productivity. The objective of this study was to determine biomass yield and quality of fodder from selected lablab varieties. Eight lablab varieties namely, DL1002, Ngwara Nyeupe, Echo-Cream, Black-Rongai, Eldo-KtCream, Eldo-Kt-Black1, Brown Rongai and Eldo-Kt-Black2 were established in three sites of Nandi south sub county, Kenya. Randomized complete block design was used at farm level with four replications per site. Data on biomass yield, chemical composition and in vitro-dry matter digestibility of the eight lablab forages was collected. Biomass yield differed significantly among the lablab varieties ranging from 5.6-12.6 t DM/ha across the three sites. Highest biomass yield was recorded for Brown Rongai (12.6 t DM/ha) and lowest with DL1002 (5.6 t DM/ha). Crude protein (CP) content varied significantly between varieties with sites ranging from 19.6- 23.9 g/100g. Highest CP was recorded with Eldo-Kt-Cream and Black Rongai (23.9 g/100g and 23.7 g/100g) across the three sites. For all the varieties, Neutral detergent fibre (NDF) ranged from 44.4-48.6 g/100g, acid detergent fibre (ADF) 31.6-35.7 g/100g and acid detergent lignin (ADL) 9.0-11.9 g/100g across the three sites. Highest NDF was recorded with DL1002 (48.6 g/100g), ADF with Eldoret-Kitale-Black2 (35.9 g/100g) and acid detergent lignin with DL1002 (11.7 g/100g). In vitro dry matter digestibility (IVDMD) varied significantly between varieties and sites ranging from 67.6-75.7 g/100g between the varieties across the three sites. Eldo-Kt-cream and Black Rongai had the highest IVDMD (75.7 and 74.4 g/100g) across the three sites. Eldoret-Kitale-Cream and Black Rongai varieties had better dry matter yield, crude protein and low fibre fractions compared to the other varieties signifying their potential to be recommended as supplement to low quality fodder by small-scale farmers.
Chapter 17 - Drought preparedness and livestock management strategies by pastoralists in semi-arid lands: Laikipia North, Kenya
(Elsevier, 2019-01-01) Ndiritu, S. Wagura
Drought is a major threat to people's food security and livelihoods in arid and semi-arid lands in drought-prone developing countries. The traditional responses to drought management have been largely reactive. The purpose of this study is to investigate the determinants of the choice behind the various livestock management of pastoralists in Laikipia North, Kenya, as a proxy for understanding their preparedness to cope with future droughts. Households in this semi-arid area ranked drought as the most important climate shock because it was the principal cause of the loss of their livestock. Using a multivariate probit model, the study revealed that access to private ranch grazing increased the adoption of modern livestock management strategies in the study area. The study also found that early warnings of drought allowed for better water management, adoption of improved species/breeds, and early selling of livestock or destocking as strategies to enhance livestock management. Another finding was that, as distance to market increased, pastoralists' market participation decreased, driving them to stick to traditional livestock management practices, which in turn exacerbated the households' exposure to climate shocks. Thus, improving access to markets could play a significant role in improving pastoralists' livelihoods and their traditional livelihood systems within the framework of climate change. In addition, although early warning system (EWS) is not well known in Laikipia North, there is a need for well-managed EWSs to enable households to act early on an announced drought. Since the main source of early warning information after government channels was community leaders, targeting such leaders with this information could reach many households and help them prepare adequately for climate shocks especially, severe droughts.
Characterization of kitchen and municipal organic waste for biogas production: Effect of parameters
(Elsevier, 2023-05-01) Mrosso, Register; Mecha, Achisa C.; Kiplagat, Joseph
Globally, the production of municipal solid waste is rising annually because of consumerism and the urbanization process. In the past few years, different researchers have explored strategies for generating biogas from various organic wastes. In this study, kitchen waste and municipal solid waste were characterized by several physical-chemical parameters. Ten of these substrates were mono-digested for biogas production in batch reactors where cabbage showed a 96.36 ± 1.73% volatile solid and biogas yield of 800 ± 8.8 mL within 10 days, while cooked rice had an 83.00 ± 1.49% volatile solid, and a biogas yield of 2821 ± 31.03 mL within 28 days. The CN ratio for cabbage and cooked rice waste was 13.9 and 30.9 respectively, whereas their pH values were 6.2 and 7.2. Based on the characterization and biogas yields attained, cooked rice waste could be mono-digested for biogas production and no published work showed a high yield as the current study while the other substrates require co-digestion to improve the biogas yield.
Classification of drying methods for macadamia nuts based on the glcm texture parameters
(JKUAT, 2022-03-14) Njuguna, Simon N.; Ondimu, Stephen; Kenji, Glaston M.
Texture is an important feature in the definition of the external appearance of a material. In this study, Gray-level cooccurrence matrix (GLCM) was used in the analysis of image texture without the destruction of the two varieties of macadamia nuts , KRG-15 and MRG-20, that are dried using seven different methods. Using the Imagej software, four GLCM features were computed in order to define the effect on drying methods on quality of the two varieties. These GLCM features were contrast, Angular Second Moment (ASM), homogeneity and correlation. The aim ofthis study was to investigate the influence of drying methods on the quality of macadamia nuts for the two varieties: - KRG-15 and MRG-20 with reference to texture quality. The highest classification accuracy of 77% was attained for correctly identifying influence of drying method at direction at angle of 0˚ and displacement, d=1. Solar tent drying method produces superior quality macadamia nuts for both varieties comparable to drying methods; with GLCM feature values (contrast, Homogeneity, Correlation and ASM) of 8,179, 0.048, 0.798 and 0.009 respectively for KRG-15 and 10.238, 0.789, 0.007 and 0.047 respectively for MRG-20. Combination drying of solar tent and Microwave dryingproduce the least quality,
Comparative Analysis of Crop Yields of Selected Crops (Maize, Rice and Kales) before and after The Introduction of Irrigation Technologies in Kimira-Oluch Irrigation Schemes, Homa Bay County, Kenya
(East African Scholars Publisher, Kenya, 2020-11) Makone Samson M.; Maobe Samson N.; Basweti Evans A.; Bunyatta David K.
Kenyan’s economy is heavily dependent on agriculture which contributes greatly to gross domestic products (GDP). Nearly 80% of the country’s population resides in the rural areas and are engaged directly in agricultural activities which account for over 75% of the total agricultural output. In addition, the sector contributes to food security, employment opportunities and income generation as well as nutritional balance to the farming families. It is therefore enough to say, agriculture still remains the backbone of the country’s economy because of what it offers. Kenya has a huge potential of water resources including rivers, lakes and dams for the development of irrigation systems however, the country still continues to import food especially maize despite having ability to feed its own citizens. To solve the paradox of food insecurity, irrigation technologies need to in place. This paper therefore tries to compares the yields before and after the introduction of irrigation technologies in Kenya, precisely in Kimira-Oluch irrigation scheme using a paired t-test to determine whether there is statistically significant difference between productions level per unit area of selected crops (Maize, Rice and Kales) for participants of rainfed (before irrigation) and irrigated agriculture participants. From the results it was observed that, calculated value (observed) of t was found to be -0.5150 which was in the acceptance region and thus, we accept H0 and conclude that the difference in yields before irrigation (rainfed agriculture) and after irrigation (irrigated agriculture) is insignificance hence we can infer that irrigation technologies is not applied effectively in Kimira-Oluch thus resulting to a low yields. This is a clear indication that most of the factors of production such as irrigation waters and land are underutilized. The study will assist the policy makers and irrigation stakeholder to shift focus on innovations or technologies that can benefit both irrigation participants and non-irrigation participant.
Control of Black Rot Disease in Cabbage by Integration of Mulching, Pruning and Hot Water Treatment of Seeds
(Plant Pathology & Quarantine, 2019-01) G.J Ombuna; B.J Nyangeri; S.N Maobe
Black rot disease of cabbage caused by Xanthomonas campestris pv. campestris has been a major hindering factor to cabbage production in Kisii County, Kenya. The conventional technique for controlling this disease has been the use of chemicals. However, this method of control has not been effective as the disease is seed borne. In addition, most chemicals pollute the environment and make it unconducive for the survival of other important organisms such as decomposers. In this paper, the integration of hot water treatment of seeds, mulching, pruning and plant debris management was considered as an approach that can effectively manage this disease. To achieve this objective, seeds of Gloria Hybrid cabbage were inoculated with a bacterial suspension of X. campestris pv. campestris isolated from leaf segments obtained from plant leaves with characteristics symptoms of black rot disease. A portion of the inoculated seeds were treated with hot water at 50oC for 25 minutes and later planted in the field to evaluate the effects of mulching, pruning and plant debris management on black rot disease. Another portion of the inoculated seeds were not treated with hot water and were planted to serve as a control. Disease was scored on a scale of 1–9 based on the length of the V-shaped lesions developed on the margin of plant leaves. The results obtained show that integration of hot water treatment of seeds, mulching, pruning and plant debris management led to 76.1% less black rot disease and a 78.3% increase in marketable yields. Hence such treatment is recommended as the best approach to manage black rot disease of cabbage in the field.
Dissemination of climate smart agricultural knowledge through farmer field schools (FFS): analyzing the application CAS knowledge by smallholder farmers
(Emerald Insight, 2023-01-01) Gichuki, Castro; Osewe, Maurice; Ndiritu, S. Wagura
Purpose The purpose of this paper is to investigate the effects of climate smart agriculture knowledge transfers. As well as to examine the application of climate-smart agricultural (CSA) knowledge such as conservation agriculture, irrigation systems, integrated soil fertility management, bioenergy and agroforestry by smallholder farmers in Kenya. Design/methodology/approach The study applied comparative research methodology to compare climate smart agriculture knowledge application between smallholder participants in farmer field schools (FFS) and no FFS participation. This study used household data from 759 randomly selected rural agricultural households in three counties in Kenya. The study applied multivariate probit model to estimate CSA knowledge application by farmers who participated in field trainings and non-FFS participation farmers. Findings This study established that climate smart agriculture knowledge transfer through FFS increases farmers’ application of critical aspects of climate smart agriculture knowledge practices such as irrigation system, conservation agriculture and soil and water conservation. Such aspects have been noted as effective interventions against adverse climate change effects such as persistent droughts and flooding and soil infertility. Further findings illustrated that farmers who received CSA knowledge transfers applied agricultural insurance to mitigate rising climatic risks on their farms. Knowledge transfer interventions targeting affordability through subsidizing agricultural insurance are probable and more cost-effective measures that can be used to reduce smallholder farmers’ exposure to climate change-related risks. Originality/value This study provides information that was previously unknown about climate smart agriculture knowledge transfers and application among farmers who participated in field trainings and non-FFS participation farmers by using empirical data.
Drought responses and adaptation strategies to climate change by pastoralists in the semi-arid area, Laikipia County, Kenya
(Springer Link, 2021-04-01) Ndiritu, S. Wagura
This study was undertaken in Laikipia County, Kenya, to identify factors influencing the choices of strategies by pastoralists to adapt to climate change. The study particularly evaluates the role of perceived climate extremes (frequency of dry spells and droughts), early warning information, and access to private ranch grazing, in determining response decisions to climate change. Besides, we test if households jointly adopt climate change adaptation strategies. The primary data collected from 440 sample households was analyzed using the multivariate probit (MVP) model. In the MVP model, we consider the following measures: increased mobility (distance & frequency), storage/purchase of fodder, change in water management, partial shift to other livelihoods, and herd management. The results reveal that these adaptation strategies are jointly adopted by pastoralists as complements and substitutes. From the empirical result, the perceived increase in the number of dry spells and drought, access to early warning information, access to private ranch grazing, main market distance from homesteads, and the highest level of education in the household are the key determinants of the choices of adaptation strategies to cope with drought and climate change. From a policy perspective, this research contributes to the ongoing debate on best practices by addressing climate change-related challenges in semi-arid land management. Therefore, there is a need for early warning institutions to increase their visibility in the semi-arid areas by exploring effective methods of delivering climate risk information in good time. Improving access to market and private ranch grazing should be promoted in the Kenyan semi-arid areas. Given that pastoralists’ perceptions of climate change and climate risk is a decisive variable in adaptation decision-making, there is need to improve the understanding of pastoralists’ changing climatic conditions. Furthermore, since the results indicate that mobility and storage of fodder are substitutes, the adoption of hay production could become a key production strategy for pastoralists which will increase the competitiveness of their livestock in the market and increase milk production.
Effect of Biological Control Antagonists Adsorbed on Chitosan Immobilized Silica Nanocomposite on Ralstonia solanacearum and Growth of Tomato Seedlings
(SCIENCEDOMAIN international, 2016-01-11) Gatahi Dennis; Wanyika Harrison; Kihurani Agnes; Gatebe Erastus
Background: Biological control holds promise in managing bacterial wilt disease. However, its efficacy is limited by harsh environmental conditions when applied without use of suitable carrier materials. Aim: The study entailed synthesis of nanocarrier materials for biological control agents (BCAs) using Chitosan and silica nanocomposites. Site and Duration: The experiments were carried out at Jomo Kenyatta University of Agriculture and Technology for a period of two years June 2013 to June 2015. Methodology: The experiments were conducted using a completely randomized design with three replications. Deacetylation, functionalization and immobilization of chitin on mesoporous silica nanoparticles (MSN) to form chitosan immobilized silica nanocomposites (CISNC) gel was done. Results: This resulted in formation of chitosan nanoparticles and CISNC with crystallite sizes of 2.8 and 4.4 nm respectively. BCAs were adsorbed on CISNC gel. Characterization of the bio- nanocomposites showed that they had physisorption properties thus, ideal carriers for BCAs. CISNC gel had the highest significant (P=.05) sorption properties with 75% and 65% adsorption and desorption respectively of BCAs. Efficacy trials were done by in vitro pathogen inhibition and greenhouse bioassays using tomato seedlings. Adsorption of BCAs on CISNC gel significantly (P=.05) increased inhibition efficacy of BCAs on R. solanacearum from 50 to 70%. This was attributed to the antibacterial effect of the individual substances and the overall synergy acquired. Further, BCA-CISNC gel forms a film around root hairs, initiates fast wound healing mechanism and induce prophylactic effect on tomato seedlings challenged with R. solanacearum pathogen, decreasing wilting incidences from 45 to 25%. Additionally, BCA-CISNC complex significantly (P=.05) increased tomato seed germination from 70 to 80% and growth rate from 12 to 15% due to enhanced water utilization efficiency, induced phytohormones and nutritional benefit. BCAs also aided faster nutrient release, absorption and utilization by tomato plants. Conclusion: Therefore, adsorption of bacterial, fungal and phage biocontrol agents on CISNC gel, a complex hitherto not reported to have been used in R. solanacearum disease control, enhanced microbial efficacy against the pathogen and increased tomato productivity.
Effect of Incorporating Lablab Biomass in Soils on Root Rot Disease Complex and Yield of Beans Intercropped with Maize
(International Journal of AgriScience, 2014-12) Muthomi J. W.; Mugambi, I. K.; Ojiem J.; Chemining’wa G. N.; Nderitu J. H.
Root rot is a major constraint to bean production in western Kenya causing poor crop stand and high yield losses. The disease is caused by a complex different pathogens which together exhibit synergistic effects. The pathogens survive in soils as resting spores and options of managing the disease are limited This study evaluated the effectiveness of incorporating lablab biomass in managing root rot of beans in maize intercrop system. The experimental treatments evaluated were incorporation of lablab biomass over the whole plot, biomass placed between rows of beans, biomass removed from the plot plus application of inorganic fertilizer and biomass removed from the plot without fertilizer application. In each experimental treatment, four bean varieties KK8, KK15, KK072 (tolerant to root rot) and GLP2 (susceptible to root rot) were planted intercropped with maize. The experiment was carried out at two agro-ecologically and soil fertility diverse sites. Incidence of root rot and chafer grub was determined at early growth stages while biomass and yield of both maize and beans were determined at harvest. Incorporation of lablab biomass increased soil carbon and nitrogen content but reduced both pH and cation exchange capacity. However, it reduced root rot incidence for the root tolerant bean varieties at the low soil fertility site but increased chafer grub incidence. Bean stem bases from the high soil fertility site had higher incidences of infection with Fusarium oxysporum while Fusarium solani and Macrophomina phaseolina were more prevalent in the low soil fertility site. Addition of lablab biomass significantly increased both bean biomass and seed yields in both low and high soil fertility sites. The positive effect on yield was more pronounced at the low soil fertility site. The study indicated that addition of lablab biomass to soils is beneficial in managing root rot of beans and improving crop yields in low soil fertility areas. The use of green manure soil amendments is an ecologically sustainable way of increasing bean yield for small scale farmers.
Effect of Lablab Green Manure on Population of Soil Microorganisms and Establishment of Common Bean (Phaseolus vulgaris L.)
(American Journal of Agricultural Science, 2018-11-05) Okumu Oliver Otieno; Muthomi James; Ojiem John; Narla Rama; Nderitu John
Green manures improve soil health and fertility but application of undecomposed lablab residues lead to low crop establishment. The study was carried out to determine the effect of green manure on microbial population and establishment of bean crop. Bean varieties were planted on plots each treated with lablab green manure at one ton ha-1 over whole plots and in rows, DAP fertilizer was applied at 75 kg/ha. Data was collected on microbial population, crop emergence, root rot incidence and severity, and yield. Green manure incorporation increased soil organic carbon, nitrogen, phosphorus and potassium but reduced germination percentage by about 35% and increased incidences of root rot by 30% compared to plots without green manure. The population of root rot pathogens was significantly higher in plots treated with green manure two weeks after emergence while the population of saprophytic fungi was low. Plots treated with lablab green manure reduced grain and biomass yields by 25%. Green manure increases soil nutrients directly and improves crop establishment after decomposition. Results of the study revealed a considerable increase in the population of root rot pathogens with corresponding decrease in the population of antagonistic fungi thus the poor emergence and crop establishment can be associated with increase in population of root rot pathogens and stress experienced by seeds during decomposition.
Effect of Legume Extracts on Germination, Seedling Health of Beans (Phaseolus vulgaris L.) and Soil Microorganisms
(International Journal of Plant & Soil Science, 2019-05-10) Okumu Oliver Otieno; Muthomi James Wanjohi; Ojiem John; Narla Rama; Nderitu John Huria
Application of undecomposed green manure has been reported to cause poor emergence and establishment of common beans in the field. Therefore, to understand the mechanisms’ contributing to the poor crop establishment, the effect of extracts from fresh and decomposed legume green manures on bean seed germination, fungal mycelial growth, spore germination and germ tube elongation were evaluated. The extracts were prepared in either ethanol or distilled water. Data was collected on percentage seed germination, seedling length, mycelial radial growth, spore germination and germ tube elongation. Ethanol extracts from fresh lablab inhibited bean germination by 56%, increased mean germination time to 8 days, and decreased germination index while ethanol extracts of groundnut and beans caused highest inhibition in bean shoot length and reduced biomass. Ethanol extracts from fresh green manures significantly inhibited fungal mycelia growth while the aqueous extracts from beans, groundnuts and soybean had significant level of antifungal activity while aqueous lablab extracts stimulated mycelial. Aqueous extract of lablab and soybean enhanced spore germination by over 70% with more pronounced effect on germ tube length and number of germ tubes by 8.0% and 13% respectively. The study comparatively reveals that the extract of lablab was inhibitory to common bean germination compared to other legume extracts and also stimulated the growth of root rot pathogens that may have resulted in poor establishment of beans.
Effect Of Phosphorus Fortified Compost on Growth and Yield of Maize (Zea Mays L.) And Lablab (Lablab Purpureus L.) Intercropped Maize in Acidic Soils of Western Kenya
(African Journal of Agricultural Research, 2021-02) Orandi Jairus; Mwonga Samuel; Ojiem John; Lauren Julie
Effect of phytase application on micronutrient status of plant-based foods
(ios journals, 2022) Anuro J.B; Ogutu F.O; Okumu T.M
Abstract Plant-based foods constitute an important source of carbohydrates, protein, dietary fiber and vitamins. They are also associated with anti-nutrients, whose presence result in low bioavailabity of several micronutrients causing metabolic disorders related to the nutritional factors. Of prime concern for human nutrition and health management is phytic acid. In this review the effect of phytase application on micronutrient content and bioavailability of plant-based foods was critically analyzed. PubMed and Google scholar databases were searched for articles using phytase, phytase application in cereals, plant-based foods, micronutrients and deficiency as keywords. A total of 105 articles were obtained out of which 39 were included in the review. Results indicate that application of exogenous phytase to plant-b

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