9 Records out of 22207 Records

The potential of biochar produced from Eichhornia crassipes and Prosopis juliflora to enhance soil water holding capacity of drylands soils

Author: Aller, Deborah

Awarding University: University of Edinburgh, Scotland

Level : MSc

Year: 2012

Holding Libraries: Institute of Commonwealth Studies Library ;

Subject Terms: Biochar ; Evironmental degradation ; Soils ; Eichhornia crassipes ; Prosopis juliflora ; Northern Kenya ;

Abstract:

Environmental degradation, agricultural productivity, food security, fresh water scarcity, and the adaptation to and mitigation of climate change are all significant concerns of the 21st century. Biochar is a highly porous, carbon rich material which is a natural soil amendment being investigated to address these current issues. Expanding agricultural production into dryland environments where sandy soils dominate is highly likely to be of great importance for ensuring future global food security, as population and food demands continue to increase. Sandy soils have little ability to store water, making food production difficult and crop yields an unreliable source of food and income for inhabitants living in these environments. This study looked at the water holding capacity (WHC) and hydrophobicity of Eichhornia crassipes and Prosopis juliflora for use as biochar, to potentially enhance soil moisture storage and thus agricultural productivity, with a particular focus on arid and semi-arid lands (ASALs) and northern Kenya. Both are invasive species found in Kenya which was the reason for their selection for use in this study. Biochar was produced at 350?C, 450?C, and 550?C in a Carbolite furnace and also in a Sampada gasification stove, to mimic traditional kiln char production. Biochar WHC was examined at mixtures of 2%, 5%, and 7%, corresponding to a field application rate of roughly 20 t ha-1, 50 t ha-1, and 70 t ha-1, respectively. Results demonstrated that both biochars increase soil WHC the greatest at a 7% application rate. The greatest hydrophobicity values were apparent at 350?C, with E. crassipes the more hydrophobic of the two. Mercury porosimetry analysis, which compares various characteristics of the pore space in relation to physical properties of the biochar, is consistent with the WHC data, revealing that as the total intruded volume increases the water holding capacity increases. Overall E. crassipes and P. juliflora show potential for use as biochar, but P. juliflora with its greater lignin content, is likely the better choice.

Suitability of water hyacinth Eichhornia crassipes, as a substrate for edible mushroom production

Author: Waturu, Margaret Wangari

Awarding University: Kenyatta University, Kenya

Level : MES

Year: 2007

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Mushrooms/Composting/Eichhornia crassipes/Water hyacinth/Metals ;

Abstract:

Water hyacinth Eichhornia crassipes, can be used in agriculture as compost and mulch for food production. The purpose of this research study was to investigate the suitability of water hyacinth compost in edible mushroom production and track whether heavy metals are transferred into the mushrooms. The study assessed levels of nutrients (Nitrogen and Phosphorus) and some heavy metals: Zinc, Iron, Manganese, Copper, Cadmium and Lead in dam water, water hyacinth compost and determined food safety risks that were anticipated in the mushrooms grown using the compost. Water hyacinth was harvested from Nairobi Dam, cut into small pieces, dried for two weeks and allowed to compost for a month. The compost was sterilized for six hours at 60?C, cooled and packed into sterilized plastic bags. Spawning of the compost was done in a room that was free from contaminants. The spawned bags were then incubated in a darkroom at room temperature. It took 6 weeks for the mushrooms to be ready. The experiment was set up at same conditions as existing method of mushroom growing. In the laboratory samples from water hyacinth and wheat straw composts and mushrooms were dried, ground and analyzed for nutrients (P and N). Heavy metals (Zn, Fe, Mn, Cu, Cd, Pb) were determined by Atomic Absorption Spectrophotometer. The data obtained was subjected to analysis of variance (ANOVA). The results indicated that the overall mean levels of Zinc, Iron, Manganese, Phosphorus and Nitrogen were: 0.181, 1.431, 0.465, 1.38% and 29.2% respectively for mushrooms grown using water hyacinth compost. Mean levels for Zn, Fe, Mn, P and N were 0.123, 1.226, 0.58, 1.79% and 26.67% respectively for mushroom from wheat straw compost (control). Cadmium, Copper and Lead were below detection limit. The results showed that most of the heavy metals; Zn, Fe, and Mn in mushrooms were in concentrations below the World Heath Organization guideline values and hence mushrooms grown using water hyacinth compost are fit for human consumption according to the experimental findings. Iron and Manganese were present in composts in concentrations mostly above the WHO guideline values. Therefore, it is concluded that, with respect to WHO maximum admissible concentration in foods, composts had high Iron and Manganese concentrations but mushrooms grown using the same composts had acceptable levels.

The impact of water hyacinth (Eichhornia crassipes) on the productivity,profitability and species composition of the Lake Victoria fishery,Kenya

Author: Wawire, Noah W O

Awarding University: Moi University, Kenya

Level : PhD

Year: 2005

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Fish/Fishing industry/Lake Victoria, Kenya/Water hyacinth/Eichhornia crassipes/Economics/ ;

Abstract:

One of the sectors gravely hampered by water hyacinth (WH) in Lake Victoria (Kenya) is the fishery sector. This has prompted the need to develop an approach for modeling impacts of WH on fish production. The main objective of this study was to assess the impact of WH on productivity, profitability and fish species composition on the L.Victoriafishery in Kenya. The study area consisted of the Kenya shoreline that covers about 6% of the L. Victoria and was divided into three segments. Both survey as well as time series data were used in this study. Cost Benefit Analysis (CBA) was used to analyze the profitability of fishing with and withoutWH, while Production Functions (PF) were used to establish determinants of fish production using cross sectional data. Error Correction Models (ECM) were used to analyzebeach sample time series data for 1990-2000 to assess the effect of WH, climate and fish prices on the major L. Victoria fisheries. The Vector Auto Regression (VAR) modelswere used to measure the effect of fish price and WH intensity on fish species composition in L. Victoria (1986-2000). The survey results showed that WH critical period(s) ranged between 1996-1999, while fishing costs increased by 35% and decreased net income by 52%. The PFs identified positive significant effects of fishing crew on Nile perch (1% level) and Tilapiines (10% level) on fish catch. Similarly, boat size significantly and positively affected combined catch and Nile perch at 1% level. WH had significant .negative impacts on combined catch and Tilapiines, both at 5% level, and a positive impact on mixed fish spp (1% level). The ECM results also showed significant and negative impact of WH on Tilapiines in Kendu Bay and Dunga beach at 1% level and Uhanya at 5% level. Significant and positive impacts were realized on mixed fish spp. in Kendu Bay (1%) level) and Uhanya beach (5% level), and Nile perch (10% level) in Kendu Bay. In the long run, price had more significant impacts (at 10% level) in most of the fisheries as compared to the rainfall factor. However, there were fewer statistical significant impacts at 10% level in the short run for both factors. Trend analysis in the fish species composition indicated an increase in the mixed Tilapiines and Protopterus, while there was a decline in the Rastrineobola argentea and Mormyrus. Impulse response analysis indicated that a 10% shock in WH led to a decline of fish catch for R. argentea by 1.5% and an increase in Protopterus by 8%, mixed Tilapiines by 10% and Haplochromis by 2%. ( Since the benefits of WH are realized on the less commercial fish species, there is need to develop a suitable surveillance and control system for WH in order to keep this weed below econornic injury levels. The CBA, PF, ECM and VAR models were recommended for impact assessments of WH on L.Victoria fisheries. The choice of the model to be used in a given study will depend on the objectives and data availability.

The biology and impact of Neochetina weevils on water hyacinth, Eichhornia crassipes in Lake Victoria basin, Kenya

Author: Njoka, Stephen Wangai

Awarding University: Moi University, Kenya

Level : DPhil

Year: 2004

Holding Libraries: Moi University Margaret Thatcher Library ; Kenya Agricultural Research Institute Headquarters Library ;

Subject Terms: Lake Victoria, Kenya ; Water hyacinth ; Eichhornia crassipes ; Weevils ; Neochetina bruchi ; Neochetina eichhornia ; Pest control ;

Abstract:

Lake Victoria, like other large Lakes in the world, is a shared resource and forms an international boundary between Kenya, Uganda and Tanzania. It is the second largest fresh water Lake in the world with an area of 69,000 Km2, a convoluted shoreline of 4800 km and a volume of 2,700 km '. The Lake lies in one of the most populous regions in the world, serving as a source of livelihood for some 30 million people in Kenya, Uganda and Tanzania who depend on it for fisheries, transport, power generation, biodiversity conservation, tourism, recreation, agricultural, industrial and domestic needs. Current estimates put the annual fish catch between 400,000 and 500,000 metric tonnes generating some US$300-400 million. In Kenya about 90% of the total fish landed is from this Lake. Its fishery directly employs about 100,000 people but more than 2 million people are involved in other indirect activities. The invasion of this fresh water body by the world's worst aquatic weed, water hyacinth, Eichhornia crassipes in the early 1990s posed a serious challenge to the widely acknowledged Biological Control strategy. In its native range in the Amazonian Brazil, its natural enemies keep the weed in check. The most important of these are two Curculionidae weevils, Neochetina bruchi Hustache and Neochetina eichhorniae Warner. While control has been attained with remarkable success elsewhere in the world using these weevils, no information is available on the biology, population dynamics and their impact on water hyacinth in the Lake Victoria Basin. The studies were therefore undertaken to fill these information gaps. The mean fecundity of the two weevils was recorded as 290 and 237 eggs per female laid over a period of 16 weeks, with an adult longevity of 98 and 112 days for Neochetina bruchi and Nieichhorniae respectively. A two-way analysis of variance showed there was significant difference between the egg laying capacities of the two weevil species (p=0.002). The survival rate of the two species was significantly different (p<0.05) for all life stages except for larvae to pupa. There was no significant interaction between the species and the method of egg setting (p<0.05). These studies were conducted in an open laboratory at KARl, Kibos. The impact of these weevils on water hyacinth was evaluated at 3 satellite ponds each in the riparian districts of Busia, Kisumu and Nyando. The parameters evaluated were fresh weight, number of ramettes, petioles, feeding scars, percent damaged petioles, laminar area and petiole length. The comparative field survival of the weevils was evaluated by recording the number of adults, eggs, larvae and pupae recovered at every site. A sample size of 18 plants was used at every site, with sampling conducted once every month for 12 calendar months at Okana (Kisumu) and Otho (Nyando). Data for Budalangi (Busia) was taken for six months only. The percent damaged petioles were consistently higher with an increase in the number of larvae (the most destructive stage) at all the sites. These weevils are effective Biological Control agents and for maximum results, they should be used synergistically for the control of water hyacinth in the Lake Victoria Basin.

Household welfare impacts of the water hyacinth (Eichhornia crassipes) in the Kenyan Side of Lake Victoria

Author: Mailu, Stephen Kyalo

Awarding University: Moi University, Kenya

Level : MPhil

Year: 2004

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Lake Victoria, Kenya ; Water hyacinth ; Eichhornia crassipes ; Welfare ; Socioeconomic factors ;

Abstract:

Lake Victoria is an important source oflivelihood for not only Kenyans residing next to it but the rest of East Africa and The Great Nile Valley. Nevertheless, Lake Victoria and therefore the livelihood of fishermen residing next to it has been adversely affected by the water hyacinth (Eichhornia crassipes) as reported in many fora. The effects of the hyacinth requires investigation and monitoring in order to forestall any adverse impacts. The first step in such a process will needless to say require an inquiry of whether impacts on household welfare negative or otherwise exist. A study was therefore undertaken aimed at answering the questions: Is the water hyacinth deleterious to household welfare? Is this impact greater for poorer sections of society? After clarifying what is meant by household welfare, an analytical framework is presented and applied to household cross sectional data from five sub-locations adjacent to the Kenyan waters of Lake Victoria. A randomly selected sample of 350 households was interviewed between January 2001 and March 2001 using a questionnaire similar in design to the World Bank's LSMS format. The instrument has the advantage of enabling a comprehensive assessment of many aspects of welfare rather than giving precise numerical values since many day-to-day policy decisions are made with the former, giving a general background of the field on which the policy play. A set of households resident in areas clear of the hyacinth was set out as a control group in this study. Majority of households reported that the hyacinth had deleterious welfare effects and OLS results strongly confirmed this result. Household expenditure (a proxy for income) was consistently larger in non infested areas in the estimated Engel relationship, 'income' coefficients were negative as expected, indicating an inverse relationship between the share of food in household budget and income. Household capital coefficients-human, physical and social all had the expected signs. In addition to these main results, constructed hypothetical markets for hyacinth control indicated non-zero values of willingness to pay, which intuitively means that such households were better off without the hyacinth. The poor, it was revealed do not necessarily suffer more than the non poor. These results have fundamental lessons for research and policy. It is evident that the poor have a lot at stake when faced with such a crisis and therefore, the hyacinth control effort should be concentrated in those areas where the poor live. The importance of education which is a manipulable factor both in the short and longterm and can improve the flexibility of households to the changing economic circumstances that accompany hyacinth invasion is noted. Measures that improve incomes would go a long way in mitigating or lessening the adverse welfare impacts of the water hyacinth. Keywords: Water Hyacinth, Household Income, Household expenditure, Food share

Natural occurrence and potential of pathogenic fungi for integrated management of water hyacinth, Eichhornia crassipes (Mart.) Solms-Laubach : Pontederiaceae, with Neochetina weevils, in Kenya.

Author: Kusewa, Teresia Mwende

Awarding University: Moi University, Kenya

Level : MPhil

Year: 2003

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Water hyacinth/Eichhornia crassipes/Lake Victoria, Kenya/Lake Naivasha, Kenya/Weevils/Neochetina/ ;

Abstract:

Studies were conducted to determine the natural occurrence of pathogenic fungi assciated withwaterhyacinth in Lakes Victoria and Naivasha in Kenya. The aim was to investigate thepotentialof integrating some of the most virulent fungal species identified, with Neochetinaweevilsfor control of the water hyacinth in Lake Victoria. Twosurveyswere conducted to collect, isolate and identify fungi associated with diseased waterhyacinth plants in December 1999 (dry season) and May 2000 (rainy season) at differentsites in Lakes Victoria and Naivasha. A total of 22 fungal species were isolated andsomewere found pathogenic to water hyacinth. In Lake Naivasha, 7 species were isolatedand identified of which 80% were found to be pathogenic. In Lake Victoria, 22 specieswere isolated and identified and 69% were found to be pathogenic on water hyacinth.Two new pathogenic taxa of Fusarium and Alternaria were recorded for the firsttimein the study area. Fungal occurrence was higher during the rainy season recordinga total of 17 species as compared to 12 fungal species recorded during the dry season. Pathogenicitytests against water hyacinth were carried out in the laboratory and screen houseat Muguga to determine the fungi that were virulent on the weed. Alternaria altemataand the new taxon of Fusarium sp. showed the highest mean disease incidence of 50.5% and 40.6% respectively at 2.5% w/v in 0.2% Tween-20 solution, six weeks after infection.Although the disease severity (DS) did not show any significant difference at P=O.OS, the new taxon of Fusarium performed better than other species (DS=27.8%). Boththe disease incidence and severity were gave a strong negative effect on the water hyacinthplant's ability to generate new leaves. Correlation analysis between new leaf turnoverwith disease incidence and disease severity gave correlation co-efficient values of -0.92 and -0.99 respectively. Screenhouse experiments showed that integration of both fungi Alternaria alternata and thenewFusarium sp with Neochetina weevils increased both the disease incidence and x diseaseseverity significantly. Alternaria alternata integrated with Neochetina weevils gave anincreaseof31.1 % in disease incidence and 16.1 % in disease severity. Integrating Fusarium sp. with Neochetina weevils showed an increase of 14.6% in disease incidence and76.0% in disease severity. The action of the fungi and Neochetina weevils was synergisticand this study recommends integration of the two control methods as part of themanagement strategy for water hyacinth in Lake Victoria. xi

The diversity of aquatic macroinvertebretes associated with water hyacinth Eichhornia crassipes (Mart) solm.(Pontederiaceae) in Kenya waters of Lake Victoria.

Author: Muli, Jones Rama

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2003

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Lake Victoria, Kenya ; Invertebrates ; Water Hyacinth ; Eichhornia crassipes ;

Abstract:

ABSTRACT NOT AVAILABLE

Effects of Water hyacinth Eichhornia crassipes Mart. Solms on diversity and abundance of aquatic macro-invertebrates especially disease vectors in Winam gulf, Lake Victoria, Kenya

Author: Munga, Stephen Odhiambo

Awarding University: Moi University, Kenya

Level : MPhil

Year: 2001

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Water hyacinth ; Eichhornia crassipes ; Lake Victoria, Kenya ; Winam Gulf, Lake Victoria, Kenya ; Kusa, Kenya ; Kongou, Kenya ; Mosquitoes ; Anopheles funestus ; Mansonia africana ; Malaria ; Schistosomiasis ;

Abstract:

This study examined species diversity and abundance of aquatic macroinvertebrates especially disease vectors (mosquitoes and snails) for a period of seven months in water hyacinth covered areas and open waters. The objective of the study was to determine the effects of water hyacinth on the diversity and abundance of aquatic macro-invertebrates, especially the disease vectors in Winam Gulf, Lake Victoria, Kenya. The relationships between the changes in physicochemical characteristics of water caused by the weed and species diversity and abundance were also investigated. Aquatic macro-invertebrates were sampled using a D-frame net once every two weeks in water hyacinth covered areas and open waters. Thirty-seven species of aquatic macro-invertebrates belonging to 12 orders were recorded in the two areas during the study period. Overall species diversity and that of mosquitoes and snails were expressed using Shannon-Weaver diversity index and Simpson's diversity index respectively. Comparison of overall species diversity revealed that, areas with water hyacinth cover had a significantly higher species diversity (t51= 37.14, P<O.OS) with mean values of 2.22 ? 0.14 and 0.92 ? 0.21 respectively .. Species abundance was also higher under the hyacinth than in the open waters. Species diversity of mosquitoes was greater under the hyacinth (2.1 ? 0.83) than in the open water (0.23 ? 0.16). Differences in the mean values were significantly different (t51 = IS. S, P<O.OS). Mosquitoes constituted 11.1% of the total organisms recorded under the hyacinth compared to only 4.0% in open waters. Similarly, significantly greater (t51 = 22.9S, P<O.OS) species diversity of snails was recorded under the hyacinth (mean 2.S2 ? 0.44) compared to the open waters (mean 0.69 ? 0.37). Snails contributed 7.4% and 9.4% of the total macro-invertebrates recorded in the open waters and under the hyacinth mat respectively. Water hyacinth-covered areas had lower mean values of temperature, pH, dissolved oxygen and total nitrogen compared to the open waters. However electrical conductivity, total dissolved solids, total suspended solids, total hardness, calcium, magnesium, total phosphorus and ammonia-nitrogen were found to be higher under the hyacinth mat than in the open waters. There was a negative correlation (P<O.OS) between abundance of Biomphalaria pfeifferi and pH (r = -0.75), dissolved oxygen (r = -0.49) and total suspended solids (r = -0.64). Positive significant correlation (P<O.OS)was found between this species and total hardness (r = +0.58). Negative correlation was also found between electrical conductivity, pH and abundance of all species of snails in the water hyacinth mat though this was not significant (P<O.OS). No significant correlation (P<O.OS) was found between all the physico-chemical characteristics and abundance of all species of mosquitoes in the open waters though there was a negative correlation (P<O.OS) between Anopheles funestus and temperature (r = -O.4S) and dissolved oxygen and Mansonia africana (r = -0.44) in the water hyacinth mat. Significant negative and positive correlation (P<O.OS) was also found between some physico-chemical characteristics and abundance of some species of the other aquatic macro-invertebrates. Results of this study indicate that water hyacinth is an important factor in changing the species diversity and abundance of disease vectors. This could have the adverse effects of favoring the prevalence of malaria and schistosomiasis among the communities in Kusa and Kongou beaches. The control and/or management of water hyacinth and the disease vectors in the lake region therefore needs to be urgently addressed.

Identification, pathogencity and disease progress of fungi associated with water hyacinth (Eichornia crassipes (Mart) solms in Kenya.

Author: Kariuki, George Muhia

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 1999

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Flowers and plants/Disease/Water hyacinth/Eichhornia crassipes/Fungi/ ;

Abstract:

ABSTRACT NOT AVAILABLE