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Browsing by Author "Onyari, Charles N."

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Adoption Determinants of Adapted Climate Smart Agriculture Technologies Among Smallholder Farmers in Machakos, Makueni, and Kitui Counties of Kenya
(2021-04) Muriithi, Lydia N.; Onyari, Charles N.; Mogaka, Hezron R.; Gichimu, Bernard M.; Gatumo, Geoffrey N.; Kwena, Kizito
The study examined the adoption determinants of adapted climate smart agriculture (CSA) technologies among smallholder farmers. A multi-stage sampling procedure was used to select a total sample of 384 households. Percentages and regression were employed in data analysis. The results revealed that 47.4% adapted to climate change using integrated farming system, intercropping, crop rotation and agroforestry. Sex (0.9%), education level (9.2%) significantly influenced adoption of the adaptation strategies. Moreover, information sources such as mobile phones (0.9%), and neighbors/friends (0.2%) negatively affected the adaptation strategies. Future policy should aim at creating more awareness through different information sources and provide local extension services.
Comparing productivity of rice under system of rice intensification and conventional flooding: A switching regression approach
(Academic Journals, 2020-10) Kaloi, Francis Kadipo; Isaboke, Hezron N.; Onyari, Charles N.; Njeru, Lucy K.
This paper examined the factors influencing rice productivity in Mwea Irrigation Scheme using the System of rice intensification (SRI) and conventional flooding (CF). Stratified sampling was used to obtain 364 smallholder rice farmers for interviewing. Data collection was done with the aid of a semistructured questionnaire and analyzed using the Endogenous Switching regression Model (ESRM). The results of ESRM revealed that factors such as household size, access to extension services, involvement in off-farm work, distance from the canal, farm size, labour use, access to credit services and years spent in rice farming were found to be significant in explaining variations in rice productivity. Furthermore, the gross margin analysis showed that the returns of SRI outweigh the returns of CF, thus making SRI more profitable than CF. The study therefore recommends that Kenya government should enhance engagement with development partners to pay attention to all significant factors which are important in making decisions in the two practices of rice production.
Determinants Influencing the Adoption of Rice Intensification System among Smallholders in Mwea Irrigation Scheme, Kenya
(Hindawi, 2021-03) Kaloi, Francis Kadipo; Isaboke, Hezron N.; Onyari, Charles N.; Njeru, Lucy K.
Rice farming has received considerable attention in developing countries and particularly in Kenya due to its impact on smallholders’ income and food security. Irrigated rice is the largest consumer of water, and its sustainability is threatened by water shortage. *is has necessitated the development of alternative irrigation water technologies, such as the system of rice intensification (SRI), which are efficient in water use with improved yields. *is study analyzed the determinants of adoption of SRI in the Mwea Irrigation Scheme where stratified sampling was used to obtain 364 smallholder rice farmers. A semistructured questionnaire was used to collect primary data, which was then analyzed using a binary logistic regression model. *e results showed that age (−0.3%) was significant but with a negative effect on adoption of SRI. Farm size (2.499%), household size (1.895%), distance from the canal (1.354%), off-farm work (3.953%), access to credit services (8.714%), access to extension services (7.809%), and years in rice farming (0.409%) were found positively and significantly influencing factors to the adoption of SRI. *erefore, this study concludes that smallholders attempt to improve rice productivity through adoption of SRI should give a special priority to all significant factors.
Development of a Water Quality Assessment Index for the Chania River, Kenya
(Taylor and Francis, 2020-11) Robert, G. K.; Onyari, Charles N.; Mbaka, J. G.
Human-related activities are known to have deleterious effects on the water quality of aquatic ecosystems, but there is limited information on the impact of these on rivers in tropical regions, such as the Chania River in Kenya. The Chania River is an important source of water for humans and animals and provides habitat for a variety of flora and fauna. This study used a Water Quality Index (WQI) to assess the suitability of the water for human use based on selected physico-chemical parameters (nitrates, Total Dissolved solids (TDS), potassium, sulphates, chlorides, copper, manganese, pH and phosphates). Sample collection was done between October 2018 and February 2019 over the dry and the wet seasons. Generally, the WQI indicated that water quality was fair to good in the dry season (19.67 to 30.10) but fair to poor in the wet season (23.17 to 89.15). It is recommended that the riparian zone of the Chania River be protected from anthropogenic disturbances in the County Kiambu.
Development of a Water Quality Assessment Index for the Chania River, Kenya
(Taylor and Francis, 2020-11) Kasyoka, Robert; Onyari, Charles N.; Mbaka, James G.
Human-related activities are known to have deleterious effects on the water quality of aquatic ecosystems, but there is limited information on the impact of these on rivers in tropical regions, such as the Chania River in Kenya. The Chania River is an important source of water for humans and animals and provides habitat for a variety of flora and fauna. This study used a Water Quality Index (WQI) to assess the suitability of the water for human use based on selected physico-chemical parameters (nitrates, Total Dissolved solids (TDS), potassium, sulphates, chlorides, copper, manganese, pH and phosphates). Sample collection was done between October 2018 and February 2019 over the dry and the wet seasons. Generally, the WQI indicated that water quality was fair to good in the dry season (19.67 to 30.10) but fair to poor in the wet season (23.17 to 89.15). It is recommended that the riparian zone of the Chania River be protected from anthropogenic disturbances in the County Kiambu.
Effect of on-farm testing on adoption of banana production technologies among smallholder farmers in Meru region, Kenya
(Emerald, 2021-08) Kirimi, Florence Kaumi; Onyari, Charles N.; Njeru, Lucy K.; Mogaka, Hezron N.
Purpose – The purpose of this paper is to investigate the effect of on-farm testing on the adoption of banana production technologies among smallholder farmers in the Meru region, Kenya. Design/methodology/approach – The study adopted a pragmatic paradigm and a cross-sectional survey design, sampling 370 and 30 farmers proportionately from 269,499 to 19,303 smallholder banana farmers in Meru and Tharaka-Nithi Counties of Kenya, respectively. Findings – The study revealed that there was an association between belonging to a banana farming testing group and the adoption of banana technology. The study also revealed that most farmers were not interested in adopting banana technologies as they preferred the use of conventional methods, due to unstable market prices, lack of subsidized banana production input, inaccessibility to technological materials, few extension experts and lack of enough demonstrations. Research limitations/implications – Some respondents were not willing to freely offer the information required for this study. This was delimited by assuring the informants of the confidentiality of their responses. Originality/value – The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The agricultural extension service providers will have more light on the underlying issues that need to be considered if meaningful interventions are to be done on various aspects of the banana value chain.
Effect of tillage method and sowing time on phenology, yield and yield components of chickpea (Cicer arietinum L.) under semi-arid conditions in Kenya
(2010) Onyari, Charles N.; Ouma, John; Kibe, A.M.
Objective: To determine the phenology, dry matter yield, grain yield and yield components of chickpea under four tillage methods and three sowing times within a semi-arid area of Kenya. Methodology and results: Field experiments were carried out at the National Animal Husbandry Research Centre, Naivasha, Kenya, between 2005 and 2007. Four tillage methods (Conventional, Strip, Furrow tillage, and double digging) and three sowing times (at onset, one week, two weeks after onset of rains) were evaluated. The experiment was a Randomized Complete Block Design replicated thrice in a split plot treatment design with tillage methods as main plots and sowing times allocated to the subplots. Days to 50% flowering and physiological maturity was 61 and 120 respectively irrespective of tillage method or sowing time in both seasons. Shoot biomass varied from 3242.1 to 4231.3 kg ha-1 in Season 1 and 3035.8 to 4556.1 kg ha-1 in Season 2 under tillage treatments, but, no significant differences in season 1 among sowing times. In season 2, the crop sown 2 weeks after onset of rains had significantly lower biomass yield. Plants in strip tilled plots had 36% more pods than other tillage methods in season I but not in 2. Sowing time had no significant effect on number of pods in season 1 but in season 2; the crop sown 2 weeks after the onset of rains had fewer pods. Grain yield was not influenced by tillage method or sowing times in season 1, but in season 2, strip tillage and sowing at the onset of rains yielded significantly higher grain yield than the other respective treatments. Mean grain yield were 1604kg /ha and 1895.95 kg/ha for season 1 and 2 respectively. Conclusion and application: Tillage methods and sowing times independently influenced growth, biomass development, yield components and grain yield in Kabuli chickpea, Var ICCV 95423 under semi-arid conditions in Kenya. The results were season -dependent. Sowing within two weeks after the onset of rains did not significantly lower biomass and grain yield. Strip tillage was superior to conventional tillage in the parameters measured. The time to 50% flowering and 50% maturity were not affected by tillage methods and sowing times. These results indicate that there is good potential for chickpea production (1.4 to 2.5 tonnes/ha) in this area which could be exploited to diversify grain legume production in Kenya.
Effects of Irrigation and Nitrogen Fertilizer Levels on Water and Nitrogen Use Efficiency and Yield of Drought Tolerant Hybrid Maize (Zea mays L.) in Embu County, Kenya
(2019) Onyari, Charles N.
Food grain shortage in Kenya is attributed to low rainfall and poor distribution in maize growing areas particularly as well as low soil fertility associated mainly with nitrogen deficiency. Use of irrigation water and nitrogen fertilizer is likely to solve this food security challenge. This study was conducted over two seasons covering 2012 and 2013 with the aim of establishing optimal irrigation and nitrogen fertilizer rates for drought tolerant hybrid maize (Zea mays L.), DK8031, grown in furrows to optimize rainfall capture with the objective of simultaneously achieving high water and nitrogen use efficiencies and yields. Four irrigation levels allocated as main plots were given: I119 - only once at sowing with 119 mm; I2 = 238 mm - at sowing and two weeks after sowing (WAS); I357 – at sowing followed by applying at two and six WAS; I476 - at sowing, followed by applying at two, six and ten WAS. These totaled to 119.05, 230.10, 357.15 and 476.2 mm of applied irrigation water, respectively, exclusive of the 542.4 and 780.0 mm seasonal rainfall received in 2012 and 2013. Nitrogen was allocated to the subplots incrementally at N0 = 0, N30 = 30, N60 = 60, N90 = 90 and N120 = 120 kg-N/ha application rates. It was observed that application of irrigation water and nitrogen positively and significantly affected biomass and grain yields as well as the yield components of the DK8031 maize variety. The highest dry matter and grain yields of 13,200 and 4,000 kg/ha were obtained with 476.6 mm applied irrigation water and 120 kg/ha nitrogen rate. The aboveground biomass and grain yields varied from 11.8 to 16.3 and 3.7 to 4.0 t/ha. The highest number of cobs per ha (47,500 to 62,778 cobs/ha), cob length (17.5 to 19.9 cm) and lines per cob (12.9 to 13.4) were achieved at I476N120 treatment combination in both season and increased with additional inputs, implying higher production potential at higher values of irrigation levels and fertilizer rates. The biomass and grain based water use efficiencies decreased with increase in irrigation but increased with increasing nitrogen rates and ranged from 8.2 to 12.8 kg-DM/ha-mm and 4.3 to 4.4 kg-grain/ha-mm in Season I and II, respectively. Linear and quadratic production functions developed predicted yields with high certainties (R2) ranging between 0.60 and 1.00. Optimal yield was obtained with 357 mm supplemental irrigation water and 90 kg-N/ha of application nitrogen. Farmers in Embu can grow the DK8031 maize with at least 238 mm and 357 mm depth of supplemental irrigation at nitrogen rates of 90 and 100 kg/ha to promote productivity of the crop in the October to March and April to September seasons, respectively.
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 Variety, Spacing and Nitrogen Application on Chickpea (Cicer arietinum) Growth and Yield in Embu County, Kenya
(2022-02) Wafula, Judith N.; Mugendi, Fredrick N.; Nthakanio, Paul N.; Mosioma, Jeremiah O.; Onyari, Charles N.
Chickpea is a pulse crop that is rich in proteins and helps in fulfilling the requirement of protein for vegetarian people thus yield maximization needed. This study aimed to determine the effects of spacing, nitrogen rates, and their interactive effects on the growth and productivity of the selected chickpea varieties. Field experiments were conducted at Mwea, Kenya between 2017 and 2018 involving four varieties (Saina K, Mwanza 2, Chaina I and Chaina III) at a spacing of 50x10cm, 50x20cm, and 50x30cm, and starter nitrogen-fertilizer application rates 0kg, 30kg, 60kg, and 90kg ha -1 Starter nitrogen fertilizer . A split-split plot design arranged in a 4x3x4 layout was used in the current study. Data related to plant height, biomass, grain yield, and harvest index were collected and subjected to statistical analysis by GLM in SAS 9.4 computer software. Variations occurred in measured traits like the height of crops (34.8138.00cm), biomass yield (3.31 - 8.08t ha Interactions Yield -1 ), seed yield (0.14 to 1.9t ha -1 ), and percent harvest index (5 - 45%) was reported. Mwanza 2 expressed the highest plant height, biomass, and grain yield. The highest plant biomass was obtained under 50x10cm spacing, while the highest grain yield weight was reported under 50x30cm spacing x 60kg N ha -1 . From the results of the study, it can be concluded that the highest enhanced growth and productivity of chickpea were realized at interactions of Mwanza 2x50x10cmx90kg ha -1 nitrogen rate in the study area.
Evaluating the surface functional groups on banana leaf petioles and the resultant biochar for potential adsorbance
(JMES, 2020) Ndung’u, Paul W.; Mwithiga, Gikuru; Onyari, Charles N.; Muriithi, Genson; Mukono, Simon T.
The presence of surface functional groups is key to the performance of an adsorbent material. The aim of this study was to evaluate the presence of functional groups on banana leaf petiole and on biochar made from banana leaf petiole. These functional groups assist in determining the potential of the material as an adsorbent for pollutants and heavy metals in waste water. Banana leaf petioles were collected from a single plantation and analyzed using the Fourier transform infrared spectroscopy. The material was then pyrolyzed at pyrolytic temperatures of 300°C, 400°C and 500°C, and the resulting biochars were analyzed to identify the surface functional group. The results showed the presence of hydroxyl and carboxyl functional groups on the banana leaf petiole before pyrolysis. The biochars also showed presence of hydroxyl and carboxyl functional groups whose presence and abundance reduced with increase in pyrolytic temperature. The presence of hydroxyl and carboxyl functional groups in a material has been related to its ability to adsorb metals in waste water and thus the banana leaf petiole as well as its resulting biochar would be a promising adsorbent for waste water remediation
Extension-Market Linkages on Banana Commercialisation Among Smallholder Farmers in Meru Region, Kenya
(2022-01) Kirimi, Florence K.; Onyari, Charles N.; Njeru, Lucy K.; Mogaka, Hezron R.
The study examined the effect of extension-market linkages on banana commercialisation among smallholder farmers in the Meru region, Kenya. The study sampled 400 farmers from a target population of 288,802 from the Meru region. The Tobit model was used to analyse the effect of extension-market linkages on banana commercialisation. The results revealed that sources of marketing information (Coef. -0.06) had a negative influence on farmers commercialising banana production. The result showed that the reliability of local extension service providers in enabling farmer’s access to market information (Coef. 0.04) had a positive influence on farmers commercialising banana production. The findings also showed that users of marketing information in the commercialisation banana business (Coef. 0.63) had a positive influence on farmers commercialising banana production. The study concludes that there was an association between extension marketing linkages and banana commercialization among smallholder farmers in Meru region, Kenya. Government should create and implement more policies that will favour and encourage farmers to commercialise bananas. This will help farmers increase their income.
Growth Parameters of DK8031 Maize Variety as Affected by Varying Irrigation and Nitrogen Fertilizer Rates in Embu County, Kenya
(David Publishing, 2015) Onyari, Charles N.; Kibe, Antony M.; Mwonga, Samuel
Determination of crop growth parameters of maize helps assess the performance of the crop for food security. A study was conducted in two seasons covering 2012 and 2013 to establish optimal irrigation and nitrogen fertilizer rates for drought tolerant hybrid maize (Zea mays L.), DK8031 variety, in sandy loam soils using furrow irrigation. Four additive irrigation levels (119.05 mm, 238.10 mm, 357.15 mm and 476.2 mm) were allocated the main plots while five nitrogen fertilizer rates (0 kg/ha, 60, 75 kg/ha, 90 kg/ha and 100 kg/ha) were allocated the sub-plots. Both irrigation and nitrogen fertilizer treatments significantly enhanced crop growth parameters under consideration. Stand count per treatment plot, plant height and number of leaves per ranged from 45-59 plants/plot, 215-238 cm and 14-16 leaves respectively. It was concluded that use of supplementary irrigation and phased nitrogen fertilizer rates for maize growing in areas such as Embu can greatly promote crop growth.
Influence of institutional factors on Sorghum production in Nakuru County, Kenya
(Academe Research Journals, 2012-12) Ogeto, Robert M.; Mshenga, Patience; Cheruiyot, Erick; Onyari, Charles N.
Agriculture in Kenya plays an important role in development as it contributes about 24% of GDP, 75% of industrial raw materials and 60% of export earnings and about 18% of the total formal employment. It also employs about 3.8 million people in farm, livestock production and fishing, while an estimated 4.5 million other people are employed in agriculture-related off-farm activities. Cereals including maize, sorghum, millet, and wheat among others largely constitute the major food items for many households, hence underlining their importance in ensuring food security. In particular, the utility of sorghum is in its climatic adaptability and household as well as industrial use. Hence it is not only a food security crop, but also a major income earner. Despite its utility, there is a remarkably low production of sorghum among Kenyan farmers against food security challenges. This paper provides insights into the institutional characteristics of farmers and how they influence their participation in its production. The institutional factors under study included access to sorghum seed, access to credit, access to contract farming, access to market information and group membership. Simple random and snowball sampling methods were applied in collecting data from 207 farmers using a questionnaire. Data collected was analyzed by the double hurdle model. Only access to seed, access to extension, access to market information and access to group membership were significantly influencing sorghum production in the study area. It was recommended that seed companies should avail improved sorghum varieties and farmers are encouraged to adopt them. There was also need for stakeholders to institutionalize access to extension, contract farming and group membership among farmers.
Inter-seasonal Effects on Selected Maturity Parameters of DK8031 Maize Grown under Varying Irrigation and Nitrogen Levels in Embu County, Kenya
(2017-07) Onyari, Charles N.; Kibe, Antony M.; Mwonga, Samuel
Maize is a staple food and a source of carbohydrates to a large proportion of people in Kenya. The performance of crop plants such as maize depends on a number of factors such as climate, soil characteristics and plant species. The maturity parameters such time to tassel, milk stage, physiological maturity and biological maturity are consequently affected which in turn has an influence on crop performance. A study was carried out at University of Embu Demonstration Farm that lies at 03° 30 ′ S latitude, 37° 30 ′ E longitude, and altitude 1480 m above sea level, soils being Humic Nitisols. To evaluate the effects of seasonal weather variability on maturity parameters of DK8031 maize, a CRBD in a split plot experimental arrangement was set up in which four irrigation levels (I) and five nitrogen fertilizer rates (N) were allocated the main and subplot treatments in two seasons, respectively. The results revealed that the irrigation levels and nitrogen rates significantly (P<0.05) affected the time to reach the 50% tasseling, 50% milk stage and 50% physiological maturity, ranging from 69 to 73, 99 to 107 and 128 to 140 days after planting, respectively. In all cases, Season I (cool and less rainfall, 530.3 mm) crop took longer to reach any the three developmental stages, compared to Season II (warm and more rainfall = 605.6 mm). The time variation in reaching the developmental stages was attributed to the seasonal weather conditions. Farmers can opt to plant their maize crop in Season II to take advantage of the shorter period the crop takes to mature.
Production Functions and Their Use in Predicting Chickpea Biomass Yields When Grown under Varying Tillage and Sowing Dates in Naivasha, Kenya
(Scientific Research Publishing Co., 2007) Kibe, A.M.; Onyari, Charles N.
The use of production functions as tools for analyzing agronomic relationships and crop growth is gaining importance the world over. Their predictive value in crop adaptation trials for specific agro-ecological sites particularly in semi arid lands is of special interest, but little, if any work is being done with this regard in Kenya. A chickpea (Cicer arietinum L.) cultivar, ICCV 95423 was therefore planted under four tillage systems namely, Conventional (CT), Double Digging (DD), Furrow (FT) and Strip Tillage (ST) and under three sowing dates (two weeks apart) at Naivasha. The aim was to develop evapotranspiration and biomass yield (ET-yield) relationships and determining their potential use in analyzing growth (LAI and DM production) of chickpea. Estimated yields (computed) were produced using the 1st season`s (Jan-May `05) functions and validated with the 2nd season (Jun-Oct ‘05) actual yield data sets. The relationships exhibited very high regression correlation coefficients (R2>0.93) indicating the potential reliability of the functions in predicting chickpea yields. Rate of increase in biomass production per hectare millimeter increase in water use was 17.5kg ha-mm 1. Biomass yields estimated from season II ET data were validated and had a reliability of 0.859 and 0.952 when linear and curvilinear functions were fitted, respectively. The January to June crop produced DM at a higher rate of 685.2 kg ha 1 per unit LAI as compared to 309 kg ha 1 LAI -1 for season II crop. Quadratic functions proved able to account for more variations in DM production than linear functions. They can therefore, be used reliably in analyzing and predicting DM production of chickpea in Naivasha. Chickpea has great agronomic potential for use as a food and forage crop in the dry highlands of Kenya.
Productivity of Selected Cabbage Varieties under Varying Drip Irrigation Schedules in Humic Nitisols of Embu County, Kenya
(Hindawi, 2021-05) Onkoba, Stephen O.; Onyari, Charles N.; Gichimu, Bernard M.
Use of controlled irrigation in vegetable production is considered a viable option for optimizing input use and productivity. %is study aimed at assessing the eﬀects of diﬀerent drip irrigation schedules on productivity and proﬁtability of three cabbage varieties grown in humic nitisols of Embu County. %e study was laid out in a split plot design arranged in Randomized Complete Block Design (RCBD). %e drip irrigation schedules were allocated the main plots and crop varieties allocated the subplot treatments. Cabbage test varieties investigated were Riana F1 (V1), Gloria F1 (V2), and Triperio F1 (V3). Irrigation schedule one (S1) involved application of irrigation water twice a week, S2 once a week, and S3 once every two weeks. Soil water content was determined before irrigation and then replenished to ﬁeld capacity using a known volume of water. %e data were subjected to Analysis of Variance using SAS version 9.4. Mean separation was done using Fisher’s least signiﬁcant diﬀerence at 95% level of conﬁdence. %e ﬁndings revealed that the yields and net revenue obtained from diﬀerent cabbage varieties were not signiﬁcantly diﬀerent. However, the cabbage yields and subsequent revenue increased as irrigation frequency increased. %e study recommends adoption of irrigation schedule S1 whose productivity remained high despite the high cost of production.
Sorghum production for food security: A socioeconomic analysis of sorghum production in Nakuru County, Kenya
(Academic Journals, 2013-12-05) Ogeto, Robert M.; Cheruiyot, Erick; Mshenga, Patience; Onyari, Charles N.
Kenya’s Vision 2030 identifies agriculture as one of the key sectors to deliver sustainable economic growth and improved livelihoods for the poor in the rural areas. However, the sector continues to face several endemic and emerging constraints that require special attention. During the first two decades after independence, Kenya’s economy grew at an average rate of 6 percent per year and this was substantially driven by a robust agriculture sector. However, until about five years ago, the overall economy barely grew, partly as a result of a decline in agricultural activities. The agriculture sector continues to face challenges in production due to frequent and prolonged drought hence the need for drought resistant crops like sorghum. The utility of sorghum is in its climatic adaptability and household as well as industrial use. However, there is a remarkably low production as well as consumption among Kenyan communities against the food security challenges. This paper provides insights into the socio-economic characteristics of farmers and the factors that influence their participation in its production. Simple random and snowball sampling methods were applied in collecting data from 207 farmers using a questionnaire. Data collected was analyzed using the double hurdle model. Of the factors under study, only land tenure, gender, farm size and educational level were significantly influencing sorghum production in the study area. It was recommended that more women should be encouraged to participate in sorghum production as it was found that they participated in sorghum production more than men.
Staff Profile - Dr. Charles Andrew Nyambane Onyari
(University of Embu, 2015-07) Onyari, Charles N.
My research interests are in crop growth/yield modeling, soil and water management, soil fertility, dryland farming, biometrics, and environmental impact assessment/audit.

Browsing by Author "Onyari, Charles N."

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