Browsing by Author "Muraya, M.M."

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Effects of Agricultural Land Use Practices on Soil Organic Carbon Stocks, Total Nitrogen and Available Phosphorous in Smallholder Farms in Embu County, Kenya
(Asian Journal of Environment & Ecology, 2022-04) Osoro, N.N.; Gathungu, K.; Muraya, M.M.
A study was conducted to determine soil organic carbon stocks (SOCs), total nitrogen (TN) and available phosphorous (AP) changes in agricultural land use practices with a focus on maize and coffee based agricultural systems along Kapingazi river catchment in Embu County. Demarcation was done into four agro-ecological zones (AEZ) following the river downstream; Lower Highland Zone 1 LH1; Upper Midland Zone 1, UM1; Upper Midland Zone 2, UM2; Upper Midland Zone 3, UM3. Soil samples were obtained from two depths of 0-25 cm and 25-50 cm across slope positions. The soil organic carbon stocks were high in LH1 at 58.38 kg/m2 whereas UM3 had least amount at 29.48 kg/m2 . The total nitrogen was higher in LH1 at 0.27% while least at UM3 with 0.07%. The LH1 had higher mean amount of available phosphorous at 19.44 ppm and least at UM3. The coffee agricultural system had more available phosphorous in LH1 at 23.75 ppm whereas maize had more in UM1, UM2 and UM3. The soil organic carbon stocks, available phosphorous and total nitrogen decreased across the AEZ. The Farm Foot Slope sampling point had high soil organic carbon stocks with the lowest amounts in the Farm Summit sampling point at both depths. The concentration of total nitrogen in coffee was high in all slope positions, whereas, available phosphorous was higher in maize. Therefore, it is concluded that topography and agriculture land use and management practices influence soil nutrient status.
Mathematical Modeling of Host - Pest Interactions in Stage-Structured Populations: A Case of False Codling Moth [Thaumatotibia leucotreta]
(Scitech Research Organisation(SRO), 2021-08) Ochwach, J.O.; Okongo, M.O.; Muraya, M.M.
False codling moth (FCM) (Thaumatotibia lucotreta) is a significant pest due to its potential economic impact on many susceptible fruits in most temperate regions of the world. Efforts to control the codling moth in the past mostly relied on the use of broad spectrum insecticide sprays, which has resulted in the development of insecticide resistance, and the disruption of the control of secondary pests. Understanding the dynamic of this pest is of great in importance in order to effectively employ the most effective control strategies. In this study, a mathematical model of host-false codling moth interactions is developed and qualitatively analysed using stability theory of system of differential equations. The basic offspring number with respect to FCM free equilibrium is obtain using next generation matrix. The condition for local and global asymptotic stability of FCM free and coexistence equilibria are established. The model is analysed numerically and graphically represented to justify the analytical results. False codling moth (FCM) (Thaumatotibia lucotreta) is a significant pest due to its potential economic impact on many susceptible fruits in most temperate regions of the world. Efforts to control the codling moth in the past mostly relied on the use of broad spectrum insecticide sprays, which has resulted in the development of insecticide resistance, and the disruption of the control of secondary pests. Understanding the dynamic of this pest is of great in importance in order to effectively employ the most effective control strategies. In this study, a mathematical model of host-false codling moth interactions is developed and qualitatively analysed using stability theory of system of differential equations. The basic offspring number with respect to FCM free equilibrium is obtain using next generation matrix. The condition for local and global asymptotic stability of FCM free and coexistence equilibria are established. The model is analysed numerically and graphically represented to justify the analytical results.
Occurrence of fungal foliar diseases of tomato in different agro-ecological zones of Kirinyaga County, Kenya
(Fundamental and Applied Agriculture, 2022-03) Ogolla, F.O.; Muraya, M.M.; Onyango, B.O.; ; ;
Tomato production is characterized by inconsistent quality and yields due to biotic constraints such as fungal foliar diseases. Information on the occurrence of the diseases in different agro-ecological zones of Kenya is scanty. This study assessed the occurrence of early blight, late blight and Septoria spot diseases in tomato farms in five agro-ecological zones (AEZ) of Kirinyaga County in Kenya (UM2, UM3, UM4, LM3 and LM4) using cross sectional survey method. Macro plots were systematically established diagonally in tomato farms and were used to assess disease incidence and severity. Incidences and severity data were subjected to analysis of variance (ANOVA) using Kruskal Wallis is H test at α = 0.05. Median comparison was performed using Steel Dwass Critchlow Fligner with bonferroni adjustment in Statistical Analysis Software (SAS) version 9.4. Incidences and severity of early blight, late blight and Septoria spot in tomato farms were significantly different (p<0.05) among the villages and agro-ecological zones. Incidence of early blight ranged from 35.7% to 76.65% with severity ranging from 17.15% to 50.87%. The incidence of Septoria spot ranged from 23.56% to 93.42% with severity ranging from 16.67% to 44.44%. The incidence of late blight ranged from 33.33% to 86.63% with severity ranging from16.67% to 33.33%. The incidence of early blight was significantly higher in AEZ UM3 (Median = 75%), the incidence of Septoria spot was significantly higher in AEZ LM4 (Median = 83.33%) while the incidence of late blight was significantly higher in AEZ UM3 (Median= 50%). The severity of early blight was significantly higher in AEZ UM3 (Median = 38.89%), Septoria spot was significantly severe in AEZ LM4 (Median = 40.28%) while late blight was significantly higher in AEZ UM4 (Median = 32.72%). It can be concluded that the incidences and severity of the three foliar fungal diseases of tomato differed in different AEZ of Kirinyaga County. These findings serve as a baseline study and can be used to enlighten farmers on tomato fungal diseases in the area. However, there is a need for studies to evaluate predisposing factors and to determine the economic impact of foliar fungal diseases of tomatoes in Kirinyaga County