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Search Results: 1 - 10 of 6104 matches for " Chris Shisanya "
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Analysis of the Key Challenges Facing Potato Farmers in Oljoro-Orok Division, Kenya  [PDF]
Amon Mwangi Karanja, Chris Shisanya, George Makokha
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.510088
Abstract:

The objective of this study was to evaluate the key challenges facing potato production in Oljoro-Orok division. Primary data were obtained from randomly selected farmers through questionnaires. Purposive sampling was used to select 300 farmers in the division. Proportionate sampling was used to select the sample of farmers in each of the four locations. The data collected were analyzed using descriptive statistics namely frequencies, percentages and means with the aid of Statistical Package for Social Science (SPSS) version 17.0 and a SWOT matrix computed. Rainfall variations, lack of clean seeds and crop diseases have been found to be the major challenges facing potato production in the division. 45% of the respondents see rainfall variation as the main cause of decreased potato yields, 33% lack of clean seeds and 6% crop diseases. The study found that farmers use crop diversification and off season approaches to adapt to rainfall variability. The study recommends adaptation measure to be applied to cope with rainfall variation. Such measures include irrigation using water available in Jacob, Terracin and Kivindo dams during dry spelt. A lot of emphases on the use of certified seeds should be done by the agriculture field officers to caution farmers from planting the same potatoes they harvested in the previous harvest.

Yield and Nitrogen Fixation Response by Drought Tolerant Tepary Bean (Phaseolus acutifolius A. Gray var. latifolius) in Sole and Maize Intercrop Systems in Semi-Arid Southeast Kenya
Chris A. Shisanya
Journal of Food Technology , 2013,
Abstract: Tepary Bean (TB), a drought tolerant bean variety has become popular among poor small-scale farmers in semi-arid Kenya, where it is predominantly intercropped with maize. The nitrogen fixation and yield of intercropping tepary bean-maize in comparison to sole crops as affected by nitrogen fertiliser application and inoculation were investigated during two successive growing seasons. Experimental design was randomised complete block with eight treatments: TB sole crop not inoculated with Rhizobium (R3254) and without N fertilizer (N), TB sole crop not inoculated with R3254 with or without N, TB sole crop inoculated with R3254 without N, TB with maize intercrop not inoculated with R3254 with or without N and maize sole crop with or without N. Each treatment was replicated four times. Significant differences (p#0.05) were observed in total plant dry between inoculated and uninoculated treatments at both 21 and 42 Days after Emergence (DAE). TB yields were significantly reduced in uninoculated intercrop. Inoculated TB treatments had significantly higher seed dry weights and yields ha compared to uninoculated. Intercropping TB and maize suppresses the yield of the -1 former under semi-arid conditions. Inoculating TB with Rhizobium strain R3254 was infective, effective and significantly improved TB yields in sole and intercrop. Soil analysis after the two cropping seasons indicated enhancement of soil N in sole TB plots above pre-planting levels. Maize plots exhibited a decline in soil N. Total N concentration in plant tissues was significantly enhanced in treatment R3254. There was a marked increase in soil P in all treatment plots following amendment.
Temperature Cooling and Warming Rates in Three Different Built Environments within Nairobi City, Kenya
George Lukoye Makokha,Chris Allan Shisanya
Advances in Meteorology , 2010, DOI: 10.1155/2010/686214
Abstract: Urban canyon, urban park, and suburban surface air temperature data for hot-wet, hot-dry, cool-dry, and warm-wet periods in Nairobi city were analyzed to detect differences in the cooling and warming rates. Measurement of temperature for thirty continuous days was done at each of the three sites for each of the above periods. The cooling and warming rates were computed on an hourly basis beginning at 6.00 P.M., the approximate time of sunset. The results of the study showed that the largest cooling and warming rates were generally experienced during the hot-dry period while the lowest during the cool-dry period. Cooling and warming rates were also found to be the highest at the suburban site and the lowest at the urban canyon site. The differences in the conditions of the built environment at the three sites could explain the cause of the differential cooling and warming rates. The study recommends proper planning of the built environment to ameliorate the problem of excessive nocturnal heat loads within the built environment.
Trends in Mean Annual Minimum and Maximum Near Surface Temperature in Nairobi City, Kenya
George Lukoye Makokha,Chris A. Shisanya
Advances in Meteorology , 2010, DOI: 10.1155/2010/676041
Abstract: This paper examines the long-term urban modification of mean annual conditions of near surface temperature in Nairobi City. Data from four weather stations situated in Nairobi were collected from the Kenya Meteorological Department for the period from 1966 to 1999 inclusive. The data included mean annual maximum and minimum temperatures, and was first subjected to homogeneity test before analysis. Both linear regression and Mann-Kendall rank test were used to discern the mean annual trends. Results show that the change of temperature over the thirty-four years study period is higher for minimum temperature than maximum temperature. The warming trends began earlier and are more significant at the urban stations than is the case at the sub-urban stations, an indication of the spread of urbanisation from the built-up Central Business District (CBD) to the suburbs. The established significant warming trends in minimum temperature, which are likely to reach higher proportions in future, pose serious challenges on climate and urban planning of the city. In particular the effect of increased minimum temperature on human physiological comfort, building and urban design, wind circulation and air pollution needs to be incorporated in future urban planning programmes of the city.
Trends in Mean Annual Minimum and Maximum Near Surface Temperature in Nairobi City, Kenya
George Lukoye Makokha,Chris A. Shisanya
Advances in Meteorology , 2010, DOI: 10.1155/2010/676041
Abstract: This paper examines the long-term urban modification of mean annual conditions of near surface temperature in Nairobi City. Data from four weather stations situated in Nairobi were collected from the Kenya Meteorological Department for the period from 1966 to 1999 inclusive. The data included mean annual maximum and minimum temperatures, and was first subjected to homogeneity test before analysis. Both linear regression and Mann-Kendall rank test were used to discern the mean annual trends. Results show that the change of temperature over the thirty-four years study period is higher for minimum temperature than maximum temperature. The warming trends began earlier and are more significant at the urban stations than is the case at the sub-urban stations, an indication of the spread of urbanisation from the built-up Central Business District (CBD) to the suburbs. The established significant warming trends in minimum temperature, which are likely to reach higher proportions in future, pose serious challenges on climate and urban planning of the city. In particular the effect of increased minimum temperature on human physiological comfort, building and urban design, wind circulation and air pollution needs to be incorporated in future urban planning programmes of the city. 1. Introduction The concentration of socioeconomic activities in urban areas can be attributed to rapid expansion of industrialisation and urbanisation. In developing countries, unplanned and fast urbanisation in cities has caused environmental problems including increase in energy consumption, alteration of the local climate, and higher amounts of air pollution [1]. One of the consequences of these problems is a consistent rise in surface temperature within the urban environment [2–4]. Such noticeable surface temperature rise in urban environment is known as the “urban heat island”. The heat island effect is the basic climatic response to urbanisation, and it begins being noticed in small to medium size cities with a population of less than 100,000 inhabitants [5–7]. Nairobi’s population has increased from 120,000 when the first census was conducted in 1948 to 2, 137,570 in the 1999 population census [8]. The city’s growth rate of about seven percent per annum is one of the fastest city growth in Africa and is projected to grow faster in future [9]. The factors causing the increase in urban temperatures are outlined by Todhunter [10] and Oke [11]. The largest increase in temperatures occurs during calm and cloudless nights [12]. During windy periods, the urban-rural temperature
Temperature Cooling and Warming Rates in Three Different Built Environments within Nairobi City, Kenya
George Lukoye Makokha,Chris Allan Shisanya
Advances in Meteorology , 2010, DOI: 10.1155/2010/686214
Abstract: Urban canyon, urban park, and suburban surface air temperature data for hot-wet, hot-dry, cool-dry, and warm-wet periods in Nairobi city were analyzed to detect differences in the cooling and warming rates. Measurement of temperature for thirty continuous days was done at each of the three sites for each of the above periods. The cooling and warming rates were computed on an hourly basis beginning at 6.00 P.M., the approximate time of sunset. The results of the study showed that the largest cooling and warming rates were generally experienced during the hot-dry period while the lowest during the cool-dry period. Cooling and warming rates were also found to be the highest at the suburban site and the lowest at the urban canyon site. The differences in the conditions of the built environment at the three sites could explain the cause of the differential cooling and warming rates. The study recommends proper planning of the built environment to ameliorate the problem of excessive nocturnal heat loads within the built environment. 1. Introduction Urban geometry is one of the major factors leading to the modification of urban climate. Specifically, urban geometry that relates to the urban canopy layer (UCL) influences aspects such as increased substrate heat storage due to greater thermal admittance of surface materials and decreased latent heat fluxes arising from the replacement of soil and vegetated surfaces with impervious material [1–5]. It also leads to increase in solar radiation absorption due to lower albedo of urban materials and reduced wind speeds caused by the aerodynamically rougher urban fabric [6]. There is also the release of anthropogenic heat from domestic, commercial, industrial and transport energy sources and increased atmospheric radiation absorption from green house gases [4, 6, 7]. This paper examines the thermal behaviour of both the urban and suburban landscapes as a possible cause of the differences in the urban heat island within Nairobi city. The study proposes that the structure and composition of the urban canopy as well as the density of the built-up environment are significant factors in explaining the intensity of the modification of urban climate. 2. Study Area The study was carried out in the larger Nairobi area including the city centre, extending from longitude 1°15’S to 1°25’S and latitude 36°40’E and 37°05’E. The area extends from the Kikuyu highlands in the west to the Athi-Kapiti plains in east, covering approximately 690 square kilometers (Figure 1). Nairobi has a diversified physical environment, with altitude
Determinants of Agricultural Production in Kenya under Climate Change  [PDF]
Ifeanyi N. Nwachukwu, Chris A. Shisanya
Open Access Library Journal (OALib Journal) , 2017, DOI: 10.4236/oalib.1103583
Abstract:
Climate change has been described as the most significant environmental threat of the 21st century with vast impact mostly on agriculture, altering food production processes. As an important sector in the Kenyan economy, agriculture continues to dominate other sectors despite its declining contribution to real GDP. Given that the performance of the agricultural sector is determined by a large number of factors, the need to articulate this study has become imperative in view of the climate phenomenon. Therefore, the study examined the determinants of agricultural production in Kenya under climate change with specific interests in assessing the trend of climate variables and growth rate of agricultural production within 1970-2012 periods; estimating factors influencing agricultural production and deducing policy implications from the findings. Data used were secondary and include value of agricultural production, livestock, machines, fertilizer, agricultural land, labour, annual precipitation and temperature over the study period. These were obtained from databases hosted by the Food and Agriculture Organization (FAOSTAT), the World Bank and United Nations Development Programme (UNDP). Data analysis was done using trend analysis, log quadratic trend equation and multiple regression model. The trend results show that precipitation pattern traced out high amplitude decadal variability with the forecast showing off a slightly upward trend. In temperature, the inter-annual variability observed was wide with a forecast of a slight increase up to 2020. In terms of growth analysis, the log quadratic equation indicates that agricultural production posted a compound growth rate of 3.252% during the period while production was determined by the quantum of labour, livestock, agricultural land, precipitation and its squared term. The implication is that precipitation both on the short and long run affected agricultural production. It is recommended that ecosystem based and technologically driven adaptation measures be taken to address climate change effects on agricultural production.
Assessing Tree Species Dominance along an Agro Ecological Gradient in the Mau Forest Complex, Kenya  [PDF]
Mwangi James Kinyanjui, Chris A. Shisanya, Ondimu Ken Nyabuti, Wargute Patrick Waqo, Merceline Awuor Ojwala
Open Journal of Ecology (OJE) , 2014, DOI: 10.4236/oje.2014.411056
Abstract:

Species relative dominance by basal area was assessed along an agro ecological gradient in the Mau Forest Complex (MFC). Trees were recorded per species and diameter at breast height (D1.3) for size class D1.3 ≥ 10 cm in 60 quarter hectare plots distributed in 7 agro ecological zones (AEZ) namely LH1, LH2, LH3, LH4, UH0, UH1 and UH2. Basal area per species was used to calculate species relative dominance i.e. the proportion of basal area by a species to the total basal area of the AEZ. Species associations were analysed as the group of highly ranked species in each AEZ. Sorensons similarity index was used to calculate the proportion of similar species among AEZ. Analysis of variance compared basal area among AEZ and Tukey’s multiple comparison test used to identify specific AEZ with differences. Tabernaemontana stapfiana (Britten) was ranked first in LH1, UH1 and UH0 with relative dominance values of 22.66%, 22.89% and 30.73% respectively. It was however not recorded in any other AEZs. Dombeya goetzenii (K. Schum) occurred in 6 of the 7 AEZs but had moderate dominance values in each of the 6 AEZs. The sum of dominance values per species in all AEZs indicated no species mono-dominance and different species dominated at different AEZs. Co-dominance resulted in species associations like Tabernaemontana-Allophylus-Eke-bergia-

Sustainable Water Resources Management for Food Security in Kenya: Case of Bwathonaro Catchment  [PDF]
Chris A. Shisanya, Simon M. Onywere, Joy A. Obando
Open Access Library Journal (OALib Journal) , 2017, DOI: 10.4236/oalib.1103524
Abstract:
Food security is important in Kenya today. Bwathonaro sub-catchment in Tana catchment is experiencing food insecurity and severe water related challenges due to high population pressure and over-reliance on irrigated agriculture for livelihood. Bwathonaro river supports irrigated agriculture, which is a major source of livelihood for people in the watershed. These challenges include: water pollution, inappropriate solid waste disposal, illegal water abstraction and/or over-abstraction of water, inefficient irrigation practices, encroachment on and drainage of wetlands as well as inappropriate use of agrochemicals in wetlands. The specific objectives of the study were to 1) document current status of water resource use; 2) propose a strategy for enhancing subsistence food crop farming within the existing khat (miraa) farming system; 3) promote efficient irrigation systems that reduce water use conflict and enhance equitable distribution, and 4) work with community to improve water quality and quantity. The study adopted a four-pronged approach in the data collection procedures, namely: socio-economic surveys, participatory approaches, biophysical data and geospatial tools. Results showed that water use conflicts are persistent in the catchment. However, one Water Resource User Association (WRUA)-BWARUA, has shown consistent progress towards managing water resources for food security. The WRUA has undertaken a number of activities including ensuring that water abstractors observe permit conditions, undertaking surveillance of polluters, awareness creation on protection of wetlands, springs and river banks among other activities in the catchment. The impact of these activities has been positive and includes: reduction of conflict over water, reduction in pollution, more water flowing downstream and more water availability in the catchment for diverse uses including irrigation for agriculture, livestock and wildlife. Such practices could be used in other sub-catchments of Kenya as showcases to facilitate the sustainable use of scarce water resources for the benefit of all stakeholders.
Population Levels of Indigenous Bradyrhizobia Nodulating Promiscuous Soybean in two Kenyan Soils of the Semi-arid and Semi-humid Agroecological Zones
John M. Maingi,Nkanata M. Gitonga,Chris A. Shisanya,Berthold Hornetz
Journal of Agriculture and Rural Development in the Tropics and Subtropics , 2006,
Abstract: Soybeans grown in Africa have been selected to nodulate effectively with indigenous Bradyrhizobium spp. populations since Bradyrhizobium japonicum populations are considered absent or in very low numbers in African soils. The major objective of this study was to estimate total population of Bradyrhizobia specific to soybean in two agro-ecologically different study sites, Kiboko in Makueni District, Southeast Kenya (semi-arid to arid conditions) and Kaguru in Meru District, East Kenya (semi-humid climate) . The population of the indigenous rhizobia specific to soybeans was determined using the Most Probable Number (MPN) plant infection technique. In these experiments, the total Bradyrhizobia populations, the population sizes of taxonomically defined slow-growing Bradyrhizobia specific to soybean and the population sizes of Bradyrhizobia spp. specific to tropical Glycine Cross (TGx) varieties were determined for the two study sites. Cowpea, Vigna unguiculata, cultivar Ken Kunde I was used to estimate the total Bradyrhizobia spp. population. Clark soybean, Glycine max, was used to estimate the population sizes of taxonomically defined slow-growing Bradyrhizobia spp. specific to soybean while a TGx genotype, SB12-TGx1869-31E was used to determine the population sizes of Bradyrhizobia spp. specific to TGx varieties. The results of the MPN counts indicated that the total Bradyrhizobia population in Kiboko was between 2.59x104 and 1.89x105. The population size of taxonomically defined slowgrowing Bradyrhizobia in Kiboko was between 2.59x102 and 1.89x103 cells per gram of soil sample while the approximate Bradyrhizobia population specific to TGx genotype was between 7.81x102 and 5.67x103 cells per gram of soil. In Kaguru, the approximate total Bradyrhizobia population was between 1.04x102 and 7.56x103 cells per gram of soil. The population size of taxonomically defined slow-growing Bradyrhizobia was between 1.33x102 and 9.72x102 cells per gram of soil while the approximate Bradyrhizobia population specific toTGx genotype was between 2.37x102 and 1.73x103 per gram of soil. These populations were adequate to give satisfactory results on nodulation and nitrogen fixation in the two study sites.
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