Western Kenya (western + kenya)

Distribution by Scientific Domains

Selected Abstracts

Economic analysis of different options in integrated pest and soil fertility management in maize systems of Western Kenya

Hugo De Groote
Abstract The major biotic constraints to the production of maize, the major staple food in Western Kenya, are field pests such as,Striga,and stem borers, and low soil fertility. To counter these constraints, new cropping systems have been developed, including "push-pull," rotations with promiscuous soybean varieties and green manure crops, and imidazolinone resistant- (IR-) maize. To analyze the technical and economic performance of these technologies, both with and without fertilizer, on-farm researcher-managed long-term trials were implemented over six seasons in two sites each in Vihiga and Siaya districts of Western Kenya. The economic results, based on marginal analysis using a multioutput, multiperiod model, show that the new cropping systems with fodder intercropping (push-pull) or soybean rotations were highly profitable. Push-pull is more profitable but requires a relatively high initial investment cost. Green manure rotation, IR-maize, and fertilizer all increased yields, but these investments were generally not justified by their increased revenue. We argue that research on rotation and cropping systems to tackle pest and soil fertility problems in Africa deserve more attention. This will require increased collaboration between agronomists and economists to set up long-term experiments with new cropping systems to develop proper economic models. [source]

Becoming "One Who Treats": A Case Study of a Luo Healer and Her Grandson in Western Kenya

Ruth Prince
Using a case study of a healer and her grandson, this article shows how learning to heal is embedded in the close relationship of reciprocity and care between grandmother and grandchild in Luo society. Through shared daily life with his grandmother, the child develops social sense, respect, and compassion for people, as well as practical skills. By showing that learning to heal is not only embedded in everyday practice and in social relations, but is also a moral and emotional process, this article contributes to sociocultural theories of learning and to ethnographic accounts of childhood in Africa. [source]

Front and Back Covers, Volume 24, Number 6.

December 200
Front cover caption, volume 24 issue 6 Front cover A television newscaster reports from a prayer meeting organized in support of Barack Obama on the eve of the US election in Kogelo, Western Kenya. Foreign and local journalists descended on this small village which is home to Mama Sarah, Obama's paternal step-grandmother. As this picture was taken, religious and cultural leaders, schoolchildren and local politicians were praying for the success of their ,son', although they were also careful to offer up prayers for John McCain. The newscaster stands in front of a painting by local artist Joachim Onyango Ndalo, famous for his colourful portrayals of historical events, African presidents and other world leaders. The painting shows Obama surrounded by political figures, including Colin Powell, Bill Clinton and the British queen. In January of this year Ndalo was forced to flee from his home in Western Kenya to Uganda during the violence that followed Kenya's contested elections between the Party of National Unity (PNU), led by President Kibaki, and the Orange Democratic Movement (ODM), the opposition party led by Raila Odinga. Although pro-Odinga, the artist was branded a traitor by some members of his community for accepting a commission to paint Stanley Livondo, a Kibaki supporter and opponent of Odinga for the Langata parliamentary seat. Ndalo's workshop and paintings were destroyed. He has since returned home and plans to send his painting to America as a gift to Obama for his inauguration. Back cover caption, volume 24 issue 6 FINANCIAL CRISIS: The financial crisis unfolding since September this year has wiped out savings and threatens livelihoods across the world. Future generations will have to pay for the nationalization of gigantic debts that we never thought we had. This crisis, the worst of its kind since the Great Depression, demands an overhaul of the world's financial system. What might anthropologists contribute, beyond our insight into the world's informal economies and peasant markets? In this issue, Keith Hart and Horacio Ortiz argue that the breakdown of the economists' intellectual hegemony demands a new approach to money more sensitive to its social dimensions and to redistributive justice. A fresh reading of Mauss and Polanyi would be one good place to start. Stephen Gudeman, in his diary of witnessing the financial markets in October, argues for the relevance of anthropological concepts such as ,spheres of exchange', a realm of people, relationships and materials that cuts across market processes and lies beyond the economic vision of Wall Street and Washington, but should be represented in policy-making. Anthropologists have produced many detailed examples of how communities make use of markets within economies. Now, as the world searches for a new system of governance, is the time for anthropologists to make their voices heard. Perhaps a President's Council of Anthropological Advisors might complement the existing Council of Economic Advisors. What better time for such a proposal than the election of a new US president with roots in Hawaii, Kansas, Indonesia and Kenya, whose mother was herself an anthropologist? [source]

Nutrient constraints to tropical agroecosystem productivity in long-term degrading soils

Abstract Soil degradation is one of the most serious threats to sustainable crop production in many tropical agroecosystems where extensification rather than intensification of agriculture has occurred. In the highlands of western Kenya, we investigated soil nitrogen (N) and phosphorus (P) constraints to maize productivity across a cultivation chronosequence in which land-use history ranged from recent conversion from primary forest to 100 years in continuous cropping. Nutrient treatments included a range of N and P fertilizer rates applied separately and in combination. Maize productivity without fertilizer was used as a proxy measure for indigenous soil fertility (ISF). Soil pools of mineral nitrogen, strongly bound P and plant-available P decreased by 82%, 31% and 36%, and P adsorption capacity increased by 51% after 100 years of continuous cultivation. For the long rainy season (LR), grain yield without fertilizer declined rapidly as cultivation age increased from 0 to 25 years and then gradually declined to a yield of 1.6 Mg ha,1, which was maintained as time under cultivation increased from 60 to 100 years. LR grain yield in the old conversions was only 24% of the average young conversion grain yield (6.4 Mg ha,1). Application of either N or P alone significantly increased grain yield in both the LR and short rainy (SR) seasons, but only application of 120 kg N ha,1 on the old conversion increased yield by >1 Mg ha,1. In both SR and LR, there was a greater average yield increment response to N and P when applied together (ranging from 1 to 3.8 Mg ha,1 for the LR), with the greatest responses on the old conversions. The benefit,cost ratio (BCR) for applying 120 kg N ha,1 alone was <1 except on the old conversions, while BCRs were>1 for applying 25 kg P ha,1 alone at all levels of conversion for both seasons. Application of both N (120 kg N ha,1) and P (25 kg P ha,1) on the old conversions resulted in the greatest BCRs. This study clearly indicates that maize productivity responses to N and P fertilizer are significantly affected by the age of cultivation and its influence on ISF, but that loss of productivity can be restored rapidly when these limiting nutrients are applied. Management strategies should consider ISF and economic factors to determine optimal N and P input requirements for achieving and sustaining profitable crop production on degraded soils. [source]

Managing interdisciplinary health research,theoretical and practical aspects

Jens Aagaard-Hansen
Abstract Interdisciplinary health research can offer valuable evidence for health care managers. However, there are specific challenges regarding the management of such projects. Based on 7 years of experience from a project in western Kenya, the authors point to the need for a sufficient time horizon, a high level of communication, equity between the disciplines and the identification of appropriate evaluation criteria as issues to be considered. The theoretical framework of Rosenfield was modified to comply with the complexities of field management. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Disturbance indicators and population decline of logged species in Mt. Elgon Forest, Kenya

Joseph Hitimana
Abstract Mount (Mt) Elgon forest in western Kenya is important for biodiversity, environmental protection and socio-economic development. Characterizing forest conditions is essential for evaluation of sustainable management and conservation activities. This paper covers findings of a study which determined and analysed indicators useful in monitoring disturbance levels in the Mt Elgon Forest. A systematic survey was carried out and covered 305 plots of 0.02 ha and 250 smaller nested regeneration plots along 10 belt transects that were distributed in five blocks within the moist lower montane forest type. Collected and analysed data include types of disturbance, tree species composition, abundance and logged species. Correlation breakdown among disturbance types revealed that, paths were indicators of the number of tree harvesting sites (rs =1.00, P < 0.01) and of de-vegetated areas through grass harvesting (rs = 0.90, P = 0.04). Solanum mauritianum Scop. was an indicator of old-charcoal production sites. Logging targeted 13 tree species and harvested trees with diameter at breast height above 20 cm. The most exploited species were Olea capensis L. and Deinbolia kilimandscharica Taub. All exploited species had low regeneration but tree regeneration was not an effective indicator of logging. Résumé La forêt du Mont Elgon, dans l'ouest du Kenya, est importante pour sa biodiversité, pour la protection de l'environnement et pour le développement socioéconomique. Il est essentiel de bien définir les caractéristiques de ses conditions pour pouvoir évaluer les activités de gestion durable et de conservation. Cet article reprend les résultats d'une étude qui a déterminé et analysé des indicateurs intéressants pour pouvoir suivre le niveau de perturbation dans la forêt du Mont Elgon. Une étude systématique fut menée, qui a couvert 305 parcelles de 0,02 ha et 250 plus petites parcelles de régénération incluses le long de 10 transects de ceinture, distribuées en cinq blocs dans la forêt humide de basse montagne. Les données récoltées et analysées comprennent les types de perturbation, la composition des espèces d'arbres, leur abondance et celles qui sont exploitées. Une rupture de corrélation parmi les types de perturbation a révélé que les sentiers étaient des indicateurs du nombre de sites oùétaient récoltés les arbres (rs = 1.00; P < 0.01) et de zones sans végétation à cause de la récolte de l'herbe (rs = 0.90; P < 0.04). Solanum mauritianum Scop. était un indicateur d'anciens sites de production de charbon de bois. Les coupes d'arbres concernaient 13 espèces dont le diamètre à hauteur de poitrine dépassait 20 cm. Les espèces les plus exploitées étaient Olea capensis L. et Deinbolia kilimandscharica Taub. Toutes les espèces exploitées avaient une faible régénération, mais une régénération d'arbres n'était pas un indicateur fiable d'anciennes coupes d'arbres. [source]

Soil quality and fertilizer use rates among smallholder farmers in western Kenya

Paswel P. Marenya
Fertilizer demand; Fertilizer policy; Soil carbon; Soil organic matter; Switching regression Abstract Studies of fertilizer use in sub-Saharan Africa have been dominated by analyses of economic and market factors having to do with infrastructure, institutions, and incentives that prevent or foster increased fertilizer demand, largely ignoring how soil fertility status conditions farmer demand for fertilizer. We apply a switching regression model to data from 260 farm households in western Kenya in order to allow for the possibility of discontinuities in fertilizer demand based on a soil carbon content (SCC) threshold. We find that the usual factors reflecting liquidity and quasi-fixed inputs are important on high-SCC plots but not on those with poorer soils. External inputs become less effective on soils with low SCC, hence the discernible shift in behaviors across soil quality regimes. For many farmers, improved fertilizer market conditions alone may be insufficient to stimulate increased fertilizer use without complementary improvements in the biophysical conditions that affect conditional factor demand. [source]

Habitat characteristics of Anopheles gambiae s.s. larvae in a Kenyan highland

N. Minakawa
Abstract., Anopheline larval habitats associated with a swamp, were examined in a highland area (1910 m elevation) of western Kenya. A significant association was found between occurrence of Anopheles gambiae Giles s.s. (Diptera: Culicidae) larvae and two factors, habitat size and vegetation type. Over 80% of An. gambiae s.s. larvae were found in small isolated pools, characterized by short plants, occurring in both swamp margins and roadside ditches. However, Anopheles gambiae s.s. was not found in habitats marked by papyrus and floating plants. The larval habitat of An. gambiae s.s. was characterized by warmer daytime temperatures of water, which were significantly affected by habitat size and plant size. The density of indoor resting An. gambiae s.s. was 0.22 per house and negatively associated with distance from the swamp. These results indicate that the practice of swamp cultivation, in populated areas of the African highlands, increases availability and enhances habitat conditions for the malaria vector. [source]

Introgressive hybridization of human and rodent schistosome parasites in western Kenya

Abstract Hybridization and introgression can have important consequences for the evolution, ecology and epidemiology of pathogenic organisms. We examined the dynamics of hybridization between a trematode parasite of humans, Schistosoma mansoni, and its sister species, S. rodhaini, a rodent parasite, in a natural hybrid zone in western Kenya. Using microsatellite markers, rDNA and mtDNA, we showed that hybrids between the two species occur in nature, are fertile and produce viable offspring through backcrosses with S. mansoni. Averaged across collection sites, individuals of hybrid ancestry comprised 7.2% of all schistosomes collected, which is a large proportion given that one of the parental species, S. rodhaini, comprised only 9.1% of the specimens. No F1 individuals were collected and all hybrids represented backcrosses with S. mansoni that were of the first or successive generations. The direction of introgression appears highly asymmetric, causing unidirectional gene flow from the rodent parasite, S. rodhaini, to the human parasite, S. mansoni. Hybrid occurrence was seasonal and most hybrids were collected during the month of September over a 2-year period, a time when S. rodhaini was also abundant. We also examined the sex ratios and phenotypic differences between the hybrids and parental species, including the number of infective stages produced in the snail host and the time of day the infective stages emerge. No statistical differences were found in any of these characteristics, and most of the hybrids showed an emergence pattern similar to that of S. mansoni. One individual, however, showed a bimodal emergence pattern that was characteristic of both parental species. In conclusion, these species maintain their identity despite hybridization, although introgression may cause important alterations of the biology and epidemiology of schistosomiasis in this region. [source]

Rangewide population genetic structure of the African malaria vector Anopheles funestus

Abstract Anopheles funestus is a primary vector of malaria in Africa south of the Sahara. We assessed its rangewide population genetic structure based on samples from 11 countries, using 10 physically mapped microsatellite loci, two per autosome arm and the X (N = 548), and 834 bp of the mitochondrial ND5 gene (N = 470). On the basis of microsatellite allele frequencies, we found three subdivisions: eastern (coastal Tanzania, Malawi, Mozambique and Madagascar), western (Burkina Faso, Mali, Nigeria and western Kenya), and central (Gabon, coastal Angola). A. funestus from the southwest of Uganda had affinities to all three subdivisions. Mitochondrial DNA (mtDNA) corroborated this structure, although mtDNA gene trees showed less resolution. The eastern subdivision had significantly lower diversity, similar to the pattern found in the codistributed malaria vector Anopheles gambiae. This suggests that both species have responded to common geographic and/or climatic constraints. The western division showed signatures of population expansion encompassing Kenya west of the Rift Valley through Burkina Faso and Mali. This pattern also bears similarity to A. gambiae, and may reflect a common response to expanding human populations following the development of agriculture. Due to the presumed recent population expansion, the correlation between genetic and geographic distance was weak. Mitochondrial DNA revealed further cryptic subdivision in A. funestus, not detected in the nuclear genome. Mozambique and Madagascar samples contained two mtDNA lineages, designated clade I and clade II, that were separated by two fixed differences and an average of 2% divergence, which implies that they have evolved independently for ,1 million years. Clade I was found in all 11 locations, whereas clade II was sampled only on Madagascar and Mozambique. We suggest that the latter clade may represent mtDNA capture by A. funestus, resulting from historical gene flow either among previously isolated and divergent populations or with a related species. [source]

Hematological predictors of increased severe anemia in Kenyan children coinfected with Plasmodium falciparum and HIV-1,

Gregory C. Davenport
Malaria and HIV-1 are coendemic in many developing countries, with anemia being the most common pediatric hematological manifestation of each disease. Anemia is also one of the primary causes of mortality in children monoinfected with either malaria or HIV-1. Although our previous results showed HIV-1(+) children with acute Plasmodium falciparum malaria [Pf(+)] have more profound anemia, potential causes of severe anemia in coinfected children remain unknown. As such, children with P. falciparum malaria (aged 3,36 months, n = 542) from a holoendemic malaria transmission area of western Kenya were stratified into three groups: HIV-1 negative [HIV-1(,)/Pf(+)]; HIV-1 exposed [HIV-1(exp)/Pf(+)]; and HIV-1 infected [HIV-1(+)/Pf(+)]. Comprehensive clinical, parasitological, and hematological measures were determined upon enrollment. Univariate, correlational, and hierarchical regression analyses were used to determine differences among the groups and to define predictors of worsening anemia. HIV-1(+)/Pf(+) children had significantly more malarial pigment-containing neutrophils (PCN), monocytosis, increased severe anemia (Hb < 6.0 g/dL), and nearly 10-fold greater mortality within 3 months of enrollment. Common causes of anemia in malaria-infected children, such as increased parasitemia or reduced erythropoiesis, did not account for worsening anemia in the HIV-1(+)/Pf(+) group nor did carriage of sickle cell trait or G6PD deficiency. Hierarchical multiple regression analysis revealed that more profound anemia was associated with elevated PCM, younger age, and increasing HIV-1 status ([HIV-1(,) , HIV-1(exp) , HIV-1(+)]. Thus, malaria/HIV-1 coinfection is characterized by more profound anemia and increased mortality, with acquisition of monocytic pigment having the most detrimental impact on Hb levels. Am. J. Hematol., 2010. © 2010 Wiley-Liss, Inc. [source]

Distinct pattern of class and subclass antibodies in immune complexes of children with cerebral malaria and severe malarial anaemia

SUMMARY Plasmodium falciparum infection can lead to deadly complications such as severe malaria-associated anaemia (SMA) and cerebral malaria (CM). Children with severe malaria have elevated levels of circulating immune complexes (ICs). To further investigate the quantitative differences in antibody class/subclass components of ICs in SMA and CM, we enrolled 75 children with SMA and 32 children with CM from hospitals in western Kenya and matched them to 74 and 52 control children, respectively, with uncomplicated symptomatic malaria. Total IgG IC levels were always elevated in children with malaria upon enrolment, but children with CM had the highest levels of any group. Conditional logistic regression showed a borderline association between IgG4-containing IC levels and increased risk of SMA (OR = 3·11, 95% CI 1·01,9·56, P = 0·05). Total IgG ICs (OR = 2·84, 95% CI 1·08,7·46, P = 0·03) and IgE-containing ICs (OR = 6·82, OR 1·88,24·73, P , 0·01) were associated with increased risk of CM. These results point to differences in the contribution of the different antibody class and subclass components of ICs to the pathogenesis of SMA and CM and give insight into potential mechanisms of disease. [source]

Nitrogen and Phosphorus Release from Decomposing Leaves under Sub-Humid Tropical Conditions,

BIOTROPICA, Issue 2 2001
A. B. Kwabiah
ABSTRACT For many soils of the tropics, inputs of organic materials are essential to sustain soil fertility and crop production. Research in the quality of organic inputs, a key factor controlling rates of decomposition and nutrient release, continues to guide selection and use of organic materials as nutrient sources. The relationship between decomposition patterns and the quality parameters of the fresh leaves of six agroforestry species: Sesbania sesban, Croton megalocarpus, Calliandra calothyrsus, Tithonia diversifolia, Lantana camara, and Senna spectabilis, was investigated in a litterbag study over a period of 77 days in the highlands of western Kenya. The litterbags were buried 1 cm below the soil surface and covered with soil of ca 1 cm thickness. Percent leaf mass and total N and P that remained with time strongly correlated with total P and C/P ratio (R2= 0.60-0.90) during the first 35 days of study; but afterwards, correlation was stronger with the initial soluble polyphenolics (Pp)/P ratio (R2= 0.69-0.92) than with total P and C/P ratio. Loss of leaf mass and release of N and P followed the exponential function, yt= y0* e- kt, from which the specific decay rate constants (k) were calculated for loss of leaf mass (kB) and release of N (kN) and P (Kp). Among the plant species, the k values were lowest in Calliandra with kB= 0.012/d, kN= 0.017/d and kp= 0.044/d. Lantana had the highest K values with kg= 0.067/d and kp= 0.119/d, but the highest kN value of 0.109/d occurred in Tithonia. The kB values for all organic materials were lower than their corresponding kN and kp values, suggesting that leaching of N and P from litters may have augmented the microbial mineralization of N and P. There was a strong correlation between the kB, kN, and kp values and total P (r = 0.82-0.96; P 0.01), but not total N, lignin (LIG), or Pp. Rates of N and P release followed the general trend: Tithonia > Senna > Lantana > Sesbania > Croton > Calliandra. The results indicated that, among the quality parameters studied, total P is the most important factor controlling rate of decomposition and N and P release from organic inputs in the area of study. [source]