67 Records out of 22207 Records

Pro-poor risk management : essays on the economics of index-based risk transfer products [Kenya].

Author: Chantarat, Sommarat

Awarding University: Cornell University, USA

Level : PhD

Year: 2009

Holding Libraries: Dissertation Abstracts International ;

Subject Terms: Economics ; Essays ; Risk assessment ; Risk management ;

Abstract:

This dissertation explores innovations in index-based risk transfer products (IBRTPs) as a means to address an important insurance market failure that leaves many poor and vulnerable populations exposed to considerable uninsured risk. IBRTPs can address problems of covariate risk, asymmetric information and high transaction costs that have precluded the emergence of formal insurance market in low-income areas, where uninsured risk remains a leading cause of persistent poverty. A brief introductory chapter situates this dissertation in the broader, emergent literature on IBRTPs. The second chapter explains how the strong relation between widespread human suffering and weather shocks creates an opportunity to develop famine indexed weather derivatives to finance improved emergency response to humanitarian crises. The third chapter explains how these instruments might be designed and used by operational agencies for famine prevention in response to slow-onset disasters. It uses household data to develop a famine index based on child anthropometric data that is strongly related to rainfall variability and other exogenous measures that are reliably available at low cost; that index can be used to trigger payments to improve the timeliness and cost-effectiveness of humanitarian response. The fourth chapter develops commercially viable index based livestock insurance (IBLI) to protect livestock assets for northern Kenyan pastoralists. The underlying herd mortality index is constructed off a statistical model that relates longitudinal household-level herd mortality data to remotely sensed vegetation index data. The resulting index performs well out of sample. Pricing and risk exposure analysis also demonstrate the commercial potential of the product, which has been taken up by financial institutions in Kenya for marketing in early 2010. The fifth chapter explores the household-level performance of IBLI. It uses simulations parameterized based on household panel data, risk preference estimates elicited in field experiments and remote sensing vegetation data to explore how well IBLI performs in preserving household wealth in this setting characterized by bifurcated livestock growth dynamics characteristic of poverty traps. Willingness to pay and aggregate demand for the contract are also estimated. This analysis shows that bifurcation in livestock herd dynamics leads to nonlinear insurance valuation regardless of risk preferences.

Dairy cattle feeding and manure management on smallholder farms in Kenya.

Author: Markewich, Helen Ann

Awarding University: Cornell University, USA

Level : PhD

Year: 2009

Holding Libraries: ;

Subject Terms: Agriculture ; Cattle ; Feeds ; Dairy Industry ; Manures ; Management ;

Abstract:

The problem of declining soil fertility poses challenges to crop production on smallholder farms in the Kenyan highlands. Careful management of nutrients on resource-poor farms can support crop growth beyond subsistence needs with little or no cash expenditures by the farmer. Whether common manure management methods on smallholder Kenyan farms conserve nitrogen, a nutrient important for plant growth, was evaluated in two experiments. In the first experiment, the effects of shade and containment structure on the nitrogen composition of manure were tested in simulated storage units. The second experiment tested the effects of urine amendment on manure nitrogen composition. Both experiments tested manure age and cattle nutrition for their influence on manure nitrogen composition. Only cattle diet affected manure composition: better-fed animals produced manure with more mineralizable nitrogen available for plant uptake within one season. Up to 12% of the mineral nitrogen in manure was lost after 30 days in storage. To conserve mineral nitrogen, manure should be stored for no more than three weeks before it is applied to soil. Nutritionally adequate diets improved manure quality in terms of mineral nitrogen. Efforts to improve cattle nutrition on smallholder farms, such as supplementing diets with high-protein forages or supplements and developing models to predict production based on nutrition, are hindered by the large dietary variability in cut-and-carry systems. In a third experiment, feeding patterns on twelve small Kenyan farms were monitored. Large variations in daily feed offered and intake were observed due to forage composition, preferential feeding of high-quality feeds to adult cows, and feeding animals in groups. Specialty, non-staple forages were offered to cattle no more than 6% of the time in any season. Steps may be taken to reduce the variation in intake, such as measuring feeds offered and feeding animals individually. Simulations using the Cornell Net Carbohydrate and Protein System (CNCPS) suggest that concentrate feeds elevate the energy and protein status of cows most significantly in early lactation and are less important to cows in late lactation. Milk production may be supported by offering concentrate supplements to cows in early lactation only.

Legume crop-based soil phosphorus management and effects on maize (Zea mays) productivity in western Kenya

Author: Kapkiyai, Jane Jeptoo

Awarding University: Cornell University, USA

Level : PhD

Year: 2008

Holding Libraries: Dissertation Abstracts International ;

Subject Terms: Agriculture/Maize/Corn USE Maize/Productivity/Legumes/Western Kenya/ ;

Abstract:

The low availability of phosphorus (P) in the oxisols of western Kenya is a major constraint to crop production. Some legume genotypes posses stress response mechanisms that enhance their ability to access P in low P soils and may be useful components for integrated soil fertility management in these soils. In this study, a characterization of the spatial variability of soil properties was first assessed through geo-statistical analysis. Some selected legumes including three non P responder species, pigeon pea ( Cajanus cajan ), white lupine ( Lupinus albus ) and groundnut ( Arachis hypogaea ) and two P responders, soybean ( Glycine max ) and Lablab ( Lablab purpureus ) were evaluated for their performance in soils that had different management histories and levels of fertility degradation. Phosphorus dynamics and adsorption following incorporation of the legume residues were measured, and the effect of the legumes on growth and nutrient uptake of maize ( Zea mays ) determined. Greater anion exchange membrane (AEM) P values were obtained in less degraded soil. Plant residue addition depressed AEM P in the highly degraded soil but increased it in the less degraded soil. Legume crop residue input generally led to microbial immobilization of P. The most degraded soil adsorbed more than twice the amount of P adsorbed by the non-degraded soil. Residues of maize and soybean but not white lupin, reduced P adsorption. There was no site effect on legume biomass production and P uptake in the field, but in a pot study, non P responders performed better in the medium fertility soil while P responders showed higher performance in high fertility soil. White lupine had the lowest biomass while lablab offered the highest potential for both biomass and grain production. Maize produced more biomass and higher grain yields and had a higher nutrient uptake when grown in association with or after legumes than sole or after maize. These results show a promising potential of the studied legumes to contribute to P management in the nutrient depleted cropping systems of western Kenya. It was apparent that the benefit of the legume crops on soil nutrient availability and maize growth depended on the initial soil fertility status

Soil degradation, thresholds and dynamics of long-term cultivation : from landscape biogeochemistry to nanoscale biogeocomplexity [Kenya].

Author: Kinyangi, James Mukidza

Awarding University: Cornell University, USA

Level : PhD

Year: 2008

Holding Libraries: Dissertation Abstracts International ;

Subject Terms: Earth sciences/Soils/Farming/ ;

Abstract:

In degrading tropical soils, carbon and nutrient exports represent a significant modification to global biogeochemical cycles. We assessed soil C and nutrient losses on 122 cultivated agricultural fields from three 100-yr chronosequence sites in western Kenya. During cultivation, C stocks and soil nutrients (N, P, K Ca and Mg) were rapidly lost from the surface soil after 15-36 years of continuous cropping. A lag phase was expressed in the half life kinetics between C decline and Ca and Mg rates. For all sites, crop C 4 -C gains offset between 15 to 34% of the C losses but more than two thirds of the native forest C 3 -C was lost during 100 years of cropping. Heavy-textured Nandi soils cascaded from high to medium and low C stocks and nutrient equilibria, while medium-textured Kakamega soil, which already had lower nutrient contents instead transitioned from medium to low equilibrium of C stocks. By separating three SOM pools assigned to distinct soil functions as indicators of thresholds, we determined that nearly all C (13.6-24.3 g kg -1 ) and N (1.5-3.1 g kg -1 ) contents in the unstable and stable aggregate pools was lost 15 to 36 years after forest conversion. Long-term changes in the unstable and stable aggregate pool were characterized by rapid initial losses that reached equilibrium, a wide C:N ratio (19.3 and 18.3 respectively) and little d 15 N isotopic shift (<1.0[per thousand]). In contrast, the stable organomineral pools constituted large C and N contents which sustained only gradual non-equilibrium decay behavior. This large pool had a narrow C:N ratio with a strong enrichment of d 15 N (1.7 to 3.5[per thousand]). Continuing C and N content decline at equilibrium were linear and the severe loss of stable aggregate C and N was an indicator of low stabilization of organic matter. The long-term cultivation loss of C and soil nutrients was therefore driven by land use changes from C and nutrient-rich tropical rain forest to low equilibria of C and nutrient-poor degraded soil

Soil nutrient depletion and repletion in a tropical agroecosystem [Kenya].

Author: Ngoze, Solomon Osiru

Awarding University: Cornell University, USA

Level : PhD

Year: 2008

Holding Libraries: Dissertation Abstracts International ;

Subject Terms: Agriculture ; Soils ; Soil fertility ;

Abstract:

Soil nutrient depletion is one of the most serious threats to sustainable crop production in African agroecosystems where policy and economic factors have favoured extensification rather than intensification of agriculture. Initially, we assessed the relationship of household land use and socio economic factors on the soil fertility of over 2000 fields on 236 smallholder farms in the eastern and western highlands of Kenya. In the western highlands, soil organic matter was higher in pastures than other land uses, while the opposite was the case in the eastern highlands. Number of cattle per farm was not related to soil fertility in either region. In the highlands of western Kenya, maize productivity across a cultivation chronosequence, which ranged from recent conversion from primary forest to 100 years in continuous cropping, declined rapidly as cultivation age increased from 3 to 25 years, and then gradually declined to a yield of 1.6 Mg ha -1 season -1 . Long rainy season grain yield in the oldest conversions was only 24% of the young conversion grain yield (6.4 Mg ha -1 ). Soil pools of mineral nitrogen (N), strongly bound phosphorus (P) and plant available P decreased by 82, 31 and 36% and P adsorption capacity increased by 51% after 100 years of continuous cultivation. There was a greater yield increment response to urea N and triple super phosphate when applied together (ranging from 1 to 3.8 Mg ha -1 season -1 ) than when either fertilizer was applied alone, with the greatest responses on the oldest conversions. Tithonia diversifolia leaves or cow manure were applied at an equivalent rate of 25 kg P ha -1 . With manure, additional N was needed to sustain yield as time under cultivation increased, but not with T. diversifolia. Application of N and P together resulted in higher benefit to cost ratios (BCRs) on all conversions, with the greatest BCRs on the oldest conversions, suggesting that soil nutrient replenishment strategies should include both nutrients and consider time under cultivation. Despite BCR's >1 and positive net benefits of N and P fertilizer application, efforts to overcome nutrient depletion in these systems may be hampered by the high cost of fertilizer relative to the

Three essays on the effect of ex-ante soil fertility on smallholder fertilizer use behavior [Kenya].

Author: Marenya, Paswel Phiri

Awarding University: Cornell University, USA

Level : PhD

Year: 2008

Holding Libraries: ;

Subject Terms: Economics ; Essays ; Soil fertility ; Farming ; Fertilizers ;

Abstract:

The broad framework of this dissertation is to determine how an important soil biophysical indicator affects returns to fertilizer, secondly, whether farmers accurately perceive these biophysically mediated outcomes and thirdly, how these biophysical impacts on returns to fertilizer interact with farmers' subjective perceptions to affect fertilizer demand among a sample of smallholder farmers in a maize-based system in western Kenya. The aim is to show that these relationships can undermine market incentives for the needed increases in fertilizer use among smallholder farmers. Research results presented in this dissertation show a sigmoid relationship between soil organic matter, a broad proxy for soil fertility status, and economic returns to nitrogen fertilizer application. The results also show that farmers' subjective evaluation of soil fertility and returns to fertilizer are largely based on expected maize yields and estimated marginal returns to fertilizer. Finally, fertilizer demand exhibits significant discontinuities based on a plot-level soil carbon content cutoff point where fertilizer application was found to be significantly higher for high-soil carbon plots. These findings raise the prospect of soil quality mediated poverty traps for low-income farmers, in which degraded soil resources limit both productivity and the returns to investing in maintaining or improving the natural resource base (in this case soil fertility).

Predicting energy and protein supply and milk production of dairy cows consuming high forage rations in the eastern highlands of Kenya.

Author: Nherera, Florence Veronika

Awarding University: Cornell University, USA

Level : PhD

Year: 2006

Holding Libraries: Dissertation Abstracts International ;

Subject Terms: Agriculture ; Dairy industry ; Feeds ; Nutrition ; Predictions ;

Abstract:

Dairy cows on smallholder farms in the eastern highlands of Kenya are confined and supplied daily with varying amounts of Napier grass and crop residues. The objective of this study was to assess the nutritional adequacy of forage diets fed to dairy cattle and to identify periods of nutritional stress. A study was carried out in Embu in 2003-2004 to collect animal data and also to characterize common feeds. The data were used to evaluate the Cornell Net Carbohydrate and Protein System (CNCPS) equations for predicting intake, milk production and phosphorus excretion. The overall mean dry matter intake was similar to the CNCPS predicted value (r 2 = 0.71, mean bias = -0.24 kg/d). Dry matter intake of cows in early lactation was over-estimated by 0.81 kg/d. Prediction of milk production was also accurate with model bias of -2.2%. Predictions of milk and manure P were less accurate. The CNCPS model level 1 was used to predict nutrient requirements and evaluate diet allowable milk production of cows in early lactation. Dietary energy was inadequate to meet the requirements for most of the lactating cows and greater deficits were evident in the rations of high producing cows that freshened during the rainy seasons. These cows produced about 16 kg/d of milk and metabolizable energy (ME) deficit averaged 5.4 Mcal/d. Most cows produced about 5.8 kg of milk/d. Simulations of commonly recommended rations showed that energy supply was first limiting. Energy allowable milk from diets of mature and immature Napier grass available during the rainy seasons was 2 and 4.1 kg/d, respectively. The dry season basal diet was low in both energy and protein, supplying 80% of rumen N requirements. Addition of 2 kg DM of good quality dairy meal to the basal ration increased milk yield by 2.1 kg/d compared to 1.7 kg/d when similar amounts of Calliandra calothrysus were added. Substitution of dairy meal with calliandra in a 1:1 ration results in diets that contain excess protein but are energy deficient. Availability of affordable energy supplements and better quality forages would make increases in milk production more feasible

Assessment of land degradation attributes using near infrared spectroscopy, spatial modeling and satellite data in a tropical landscape [Kenya].

Author: Owiyo, Tom Mboya

Awarding University: Cornell University, USA

Level : PhD

Year: 2006

Holding Libraries: ;

Subject Terms: Environmental conditions ; Land ; Topography USE Cartography ; Spectroscopy USE Spectrum analysis ; Satellites ; Spectrum analysis ; Cartography ;

Abstract:

This study was designed to validate the use of visible and near infrared spectroscopy for characterizing soil properties and develop a protocol based on geographical information systems (GIS), spatial analysis and satellite remote sensing for modeling attributes of land degradation in a tropical agricultural landscape. The study had three main objectives: to develop and validate spectral models for predicting soil properties, to map the spatial distribution of soil organic carbon using (SOC) using a GIS-based spatial model and to test the use of ASTER satellite data for interpolating measurements of soil organic carbon in the landscape. Data were collected in two adjunct districts of Siaya and Vihiga in western Kenya. Near infrared spectral data were collected from soils and partial least squares (PLS) used to develop multivariate statistical models for predicting soil properties. The effect of spatial autocorrelation was assessed and found to be insignificant and spectral autocorrelation caused underestimation of the root mean squared error in the predictions. The PLS models gave good predictions for major soil properties (SOC, total nitrogen) and average predictions for exchangeable cations (Ca, Mg, K). Soil organic carbon was used as an indicator of soil quality and showed spatial autocorrelation within 400 m. This autocorrelation was used to create a GIS map showing the distribution of SOC in the study site. Soil organic carbon had a nonsignificant relationship with both the terrain attributes and the ASTER image data. These results show that a protocol that involves the use of visible and near infrared spectroscopy and GIS spatial modeling has great potential in capturing levels and distribution of important properties of soil relevant to understanding soil productivity and land degradation. Although the landscape interpolation with satellite imagery and terrain attributes was not possible, it can be concluded that the predominantly vegetated tropical agricultural ecosystems may impede the direct application of satellite imagery to assess soil degradation. Consequently, studies on soil degradation involving satellite imagery should be linked to vigor and health of vegetation or indirectly modeled on soil attributes that relate more closely with vegetation attributes like chlorophyll content which may be inferred from satellite indices like normalized difference vegetation index.

The influence of legume residue management on chafer grubs, bean root rot, and common bean productivity in western Kenya.

Author: Medvecky, Beth Anne

Awarding University: Cornell University, USA

Level : PhD

Year: 2006

Holding Libraries: ;

Subject Terms: Agriculture ; Legumes ; Beans ; Western Kenya ; Bean root rot ; Crop residues ; Management ;

Abstract:

Smallholder farmers in Trans Nzoia district, Kenya, observed a decline in bean ( Phaseolus vulgaris L.) productivity in fields where residues of the potential soil-improving legume Lablab purpureus L. had been incorporated. Research was undertaken to investigate possible linkages among soil fertility management strategies, farmers' pre-existing soilborne pest problems, and common bean productivity. An on-station trial evaluated the effects of 7 years of differential lablab and maize ( Zea mays L.) stover residue management strategies (retention, removal, mulching, incorporation) on damage by root-feeding chafer grubs ( Schizonycha spp. ) and incidence and severity of bean seedling diseases caused by soilborne pathogens ( Pythium spp. and Fusarium solani f.sp. phaseoli ) for four bean varieties. Laboratory stem and seed assays were used to assess pathogen inoculum dynamics. An on-farm experiment involving 18 replicated trials evaluated the effects of lablab residue incorporation on chafer grub abundance, post-emergence damping-off of seedlings, and bean yield in comparison to diammonium phosphate (DAP), a mixture of DAP and farmyard manure, incorporated Mucuna pruriens L. residues, and a no input check. In the on-station trial, chafer grubs damage to beans was highest in plots with a history of lablab residue retention and maize stover removal. Chafer grub damage reduced seedling dry matter production and survival and was positively correlated with soilborne disease severity and build-up of Fusarium inoculum. The four bean varieties varied in tolerance to soilborne pest pressures. In the on-farm experiment, beans had higher mortality rates and lower yields where lablab and mucuna were incorporated than where inorganic fertilizers were applied. Reduced bean productivity in the legume treatments appeared to be due to greater chafer grub abundance and low nutrient availability for the first 4-6 weeks after planting following the incorporation of the low quality legume residues. Farmers may be able to reduce lablab's negative effects by planting bean varieties that are tolerant to both root rot and grub damage and by modifying crop residue management practices. Specific modifications that are recommended include returning maize stovers to the soil, incorporating legume residues before the end of the dry season, and applying inorganic fertilizer at planting

Social networks and rural development : theory and applications in the Kenyan highlands.

Author: Hogset, Heidi

Awarding University: Cornell University, USA

Level : PhD

Year: 2005

Holding Libraries: Dissertation Abstracts International ;

Subject Terms: Economics/Rural development/Social conditions and trends/Business networking/Kenya highlands/Soil erosion/Network management systems ;

Abstract:

This dissertation addresses underlying reasons for soil degradation and stagnant or declining per capita food output in Sub-Saharan Africa. The introductory chapter presents a review of the literature on adoption of improved agricultural technologies. It concludes that slow adoption of beneficial innovations may be blamed on dysfunctional informal institutions that are embedded in social networks. Thus, a social networks study was conducted in the Kenyan highlands to analyze the relationship between social networks, informal finance and technology adoption. The second chapter develops a theoretical model of an informal insurance arrangement, and proposes that such arrangements cannot insulate poor farmers from the adoption risk associated with new technologies. The third chapter is an empirical study of economic transfers through social networks among smallholder farmers in Kenya. This chapter explores the patterns of transfers within networks, and characterizes recipients and providers of informal credit and insurance, as well as the relationship between them and the purposes such transfers serve. The main finding is that the village population is stratified into separate social networks according to wealth and income, limiting the base for risk pooling for the poorest. The fourth and final chapter analyzes social network effects on Kenyan smallholders' decisions to adopt improved natural resource management techniques. These effects are decomposed into effects from social influence and learning through networks, group effects, weak ties effects, informal finance, and conflicts arising from technological externalities, controlling for non-network effects. Contact with extension officers and membership in women's groups and youth groups have a positive effect on adoption, but the classical social learning effects appear to be weak, at least for technologies that are not new and unknown. Informal finance is not important for technology adoption. The network study reveals that rural villagers do not observe each other's technology adoption behavior very well - respondents are apparently guessing about adoption choices of their network contacts. An experiment designed to reveal how villagers access information through social networks showed that the penetration of print media in rural villages is low, but information disseminated through broadcast media reaches beyond those who have radios and television sets themselves