Abstract: The insecticidal and repellent properties of Lantana camara and Tephrosia vogelii were evaluated against Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) in stored maize grain. Five treatment rates (1.0, 2.5,5.0,7.5 and 10.0% w/w) of each powdered plant material, an untreated control and a synthetic insecticide (Actellic Super™ 2% dust) were used to investigate treatment efficacy on mortality of the adult insect (five to eight days old), F1 progeny emergence and repellency against S. zeamais adults. After 21 days, L. camara and T. vogelii caused 82.7–90.0% and 85.0–93.7% insect mortality, respectively. The mean lethal exposure times (LT50) to achieve 50% mortality varied from five to six days (7.5–10.0% w/w) to seven to eight days (2.5–5.0% w/w) for both plants. Probit regression analysis showed a significant relationship between plant powder concentration and insect mortality. The plant powders and synthetic insecticide reduced adult F1 insects by more than 75% compared to the untreated control. Tephrosia vogelii was most repellent to S. zeamais at 7.5–10.0% (w/ w), repelling 87.5% of the insects, followed by T. vogelii at 2.5% w/w and L. camara at 10% w/w which repelled 65.0 and 62.5% of insects respectively. The implications of these results are discussed in the context of smallscale farmer usage of these plants for stored product protection.

Abstract: Primary production and algal composition were studied in the shallow, highly turbid tropical freshwater Lake Baringo (Kenya). The lake's primary productivity was found to be very low when compared to other neighbouring Rift Valley lakes. The mean value of daily gross primary production was 0.56 g O2 m−2 d−1 with a range of 0.22 – 0.70 g O2 m−2 d−1. The study showed that this lake's primary production is strongly influenced by the inorganic turbidity but not the self-shading of algae as observed in the neighbouring soda and alkaline lakes. The lake has a high aphotic:photic zone ratio of 19, thus leading to a low light adapted phytoplankton community capable of vertical movement. This was shown by a uniform chlorophyll-a concentration at night and a gradient with higher values near the water surface observed during day time, too. Mean chlorophyll-a concentration was 55 μg l−1. Lake Baringo is characterised by only low diversity of algae and cyanobacteria, the latter being the major group of phytoplankton in this lake. Few green algae and diatoms were recorded during this study, growing for the most part in gelatinous sheaths of the blue-greens (strategy to get some light), on the stones near the shores of the lake and attached to the macrophytes.

Abstract: Temporal dynamics of the physico-chemical variables for Lake Baringo (Kenya) were studied between the months of May and August 2000. The results showed Lake Baringo to be a very turbid lake thus leading to bad light conditions even close to the lake's surface. Thermal stratification was observed during daytime while isothermal conditions occurred thoughout the night. Within the lake only low nitrate-nitrogen concentrations of around170 μg l−1 could be analysed, but due to clay particles total phosphorus concentrations reached 480 μg l−1. Temporal variations were observed in most of the variables analysed and seemed to be related to the hydrological regime and climate conditions. However, no significant diel patterns could be detected in these variables except for temperature and dissolved oxygen. High ionic concentrations of Na+ and Cl− ions were observed with a three-fold increase in concentration between 1965 and this study, while mg2+ and Ca2+ concentrations are low and appear unaltered during this period.

Abstract: The effects of feeding high-tannin sorghum (HTS) (5% catechin equivalents (CE)) on the performance of laying hens were examined in two experiments. In experiment 1, the effects of including varying levels of HTS in layer diets were investigated. Sixty-three Isabrown hens were randomly assigned to each of the seven diets over a period of 56 days. In experiment 2, the effects of bentonite on the utilization of HTS (3.74% CE) by laying hens were investigated. Forty-five Isabrown hens were randomly assigned to each of five diets over a period of 42 days. In both experiments, weekly measurements were made for feed intake (FI), percent hen-house production (% HHP), egg weight and egg specific gravity (ESG). The results of experiment 1 showed that the different sorghum inclusion levels had no effect (p>0.05) on HHP, egg weight and ESG, while those of experiment 2 showed that maize and LTS diets gave similar weight gain, FI and FE (p>0.05). However, HHP was higher (p 0.05) layer performance. When all the results were considered together, it was concluded that HTS can be used in layer diets without adverse effects on performance. The use of bentonite to deactivate sorghum tannins is not considered necessary.

Abstract: This paper addresses the potential for interlinked credit/input/output marketing arrangements for cash crops to promote food crop intensification. Using panel survey data from Kenya, we estimate a household fixed-effects model of fertilizer use per hectare of food crops. Results indicate that households engaging in interlinked marketing programs for selected cash crops applied considerably more fertilizer on other crops (primarily cereals) not directly purchased by the cash crop trading firm. These findings suggest that, in addition to the direct stimulus that interlinked cash crop marketing arrangements can have on small farmer incomes, these institutional arrangements may provide spillover benefits for the productivity of farmers' other activities such as food cropping.

Abstract: The abundance, biomass and composition of planktonic ciliates were studied in two Great Lakes of Africa, Malawi and Victoria, between June, 1997, and June, 1999, to investigate their role in the food webs of these lakes. Oligotrichs ( Strombidium , Strobilidium and Halteria ) were the most abundant group of ciliates in both lakes. Other important ciliates in terms of abundance and/or biomass included heterotrichs, peritrichs, haptorids, and peniculids. Mean ciliate abundance was 1.5 ciliates · mL m 1 and 20.1 ciliates · mL m 1 in Lakes Malawi and Victoria, respectively. Ciliate biomass ranged from 0.03 to 7.82 w g C · L m 1 (mean 1.8 - 0.7 w g C · L m 1 ) in Lake Malawi and ranged from 24.2 to 61.82 w g C · L m 1 (mean 36 w g C · L m 1 ) in Lake Victoria. Ciliate abundance and biomass were higher at offshore than inshore stations of both lakes despite that chlorophyll exhibited the opposite trend. Both lakes demonstrated vertical and temporal variation in their ciliate communities as well. Herbivores were...

Abstract: Retention of benthic organic matter (BOM) on the sediment surface of the Njoro River, Kenya was investigated between February 1998 and June 1999 at two sites, differing in channel morphology and riparian vegetation density and composition i.e. open-canopy and closed-canopy sites. Monthly accumulation of benthic organic matter (BOM) was highly variable, ranging from 97.3 to 6691.8 and from 206.6 to 1936.3 g ash free dry weight m -2 (AFDW) with a mean ± CL of 1133.3±794.5 and 834.9±275.8 g AFDW m -2 at the closed and open canopy sites, respectively. Pools retained higher amounts of particulate organic matter than riffles. Surprisingly, differences in retention of BOM at the two sites were not significant. Temporal distribution of benthic organic matter showed no distinct relationship with throughfall and bank runoff input patterns of particulate organic matter. Wood debris comprised 47% and 36% while leaves comprised 34% and 31%. of the total BOM at the closed and open canopy sites, respectively; the rest was fruits and fine benthic organic matter (FBOM > 0.1 mm but < 1 mm). Out of 19 plant species recorded at both sites, only 8 species reflected their contribution in BOM with Syzygium cordatum contributing over 80% of the identifiable leaf litter. It is presumed that the variations in spatial and temporal distribution of BOM at the two sites is due to differences in discharge regimes, retention structures and riparian vegetation characteristics.

Abstract: This study was carried out from April 1999 to May 2000 to investigate the extent of pollution of Lake Nakuru. Water, sediment, fish and algae collected from the lake and its feeder rivers during the dry and rainy seasons were analysed for heavy metals and organochlorine pesticide residues to identify possible sources of contaminants. Atomic absorption spectrophotometry and gas chromatography showed that more contaminants were added to the lake during the rainy season than the dry season. Heavy metals and pesticide residues were found in higher concentrations in the sediments than in the water. Contamination by most of the pollutants has increased over the past 25 years. DDD is more prevalent in the sediments and particulates in the water, but DDE is predominant in fish, suggesting two different mechanisms of DDT degradation in the biotic and abiotic environments. Whereas heavy metals tend to be distributed almost uniformly within the lake, pesticide residues are found predominantly in its northern and sou...

Abstract: Collard (Brassica oleracea var. acephala D.C) is an important source of income to many smallscale farmers in Kenya and also is a major dietary component for many Kenyans. The production of collards is, however, constrained by several pests, with diamondback moth (Plutella xylostella) larvae being the major pest. Control of the diamondback moth larvae has mainly been by chemical sprays, which has resulted in the problem of pest resistance and pollution to the environment. This study was, therefore, an attempt to look into alternative environmentally friendly ways of controlling diamondback moth larvae in collards. Two studies were conducted in Egerton University, Tatton Farm, Njoro, Kenya to determine the effects of intercropping and nitrogen application on the diamondback moth larvae population and damage, and yield of collard. Intercropping collard with either beans (Phaseolus vulgaris L.) or onions (Allium cepa) significantly lowered moth larvae populations and damage on collard leaves compared to unsprayed collard monocrop. Overall, the lowest larvae population and damage was recorded in insecticide sprayed collard monocrop. Nitrogen application increased diamondback moth damage on collard, but did not affect larvae populations. Intercropping increased crop output per unit area of land, measured by land equivalent ratios. Considering the harmful effects associated with synthetic insecticides, these results indicate that intercropping collard with either beans or onions can be effectively used to suppress diamondback moth larvae population and damage in collards. Key Words: Cropping systems, IPM, LER, Plutella xylostella Resume Le collier (Brassia oleracea var. acephala D.C) est une importante source de revenue pour les nombreux petits fermiers au Kenya et aussi un majeur composant alimentaire pour beaucoup des Kenyans. La production du collier est cependant contrainte par plusieurs insectes, avec les papillons nocturnes Plutella xylostella comme l'insecte majeur. Le controle des larves de Plutella xylostella a ete principalement par pulverisation des particles chimiques laquelle a engendre le probleme de resistance des insectes et la pollution de l'environnement. Ainsi donc, cette etude etait une tentative de voir des voies alternatives, environnementalement favorables, de controle de population et degâts des larves de Plutella xylostella dans les colliers. Deux etudes etaient conduites a l'Universite d'Egerton, et dans les fermes de Talton et de Njoro au Kenya pour determiner les effets d'intercultures et l'application de l'azote sur la population et les degâts des larves de plutella xylostella et le rendement de colliers. L'interculture de collier avec d'autres haricots (Phaseolus vulgaris L.) ou les oignons (Allium cepa) a significativement baisse les populations et les degâts des larves de Plutella xylostella sur les feuilles de colliers compare a la monoculture de collier non pulverise. Globalement, la faible population et degâts etait enregistres dans la pulverisation d'insecticide en monoculture de collier. L'application d'azote a augmente les degâts de Plutella xylostella sur les colliers, mais n'avait pas affecte les populations des larves. L'interculture a augmente la production des plantes par unite de surface de terre, mesuree par rapports a l'equivalent de terre. Considerant les effets nuisibles associes avec les insecticides synthetiques, ces resultats indiquent que l'interculture de collier avec les autres haricots ou oignons peut etre effectivement utilisee pour supprimer la population et degâts des larves de Plutella xylostella dans les colliers. Mots Cles: Systemes de cultures, IPM, LER, Plutella xylostella (Af Crop Sci J 2003 Vol 11 No 1 pp35-42)

Abstract: The Global-ITE (Initial Teacher Education) scheme is a three-year education project. It aims to enable trainee teachers in three teacher-education institutes in India, Kenya, and England to link local and global social issues to each other, and relate them to the school curriculum; and to promote a global perspective on citizenship education. Integral to our vision of global citizenship is gender equality, together with a respect for diversity. The project leaders in each country are women academics, as is the project adviser, and there is a preponderance of women students involved in the project. This gives women a voice in a vitally important area of international curriculum development. However, there are outstanding questions to be resolved about the limits on women's ability to influence change beyond the project, when men still make many operational and resourcing decisions in world politics.

Abstract: One of the expected utilitarian values of education is the development of competencies for effective business practice after school. This article presents findings of a study on the effect of education on Business Skills Cognition among indigenous microscale business owners in Kenya. Data were collected from 208 respondents using an interview schedule, observation schedule and checklist. Business Skills Cognition as the dependent quantitative variable was measured using five broad dimensions of business practice to yield a continuum of scores ranging from a minimum of 45 to a maximum of 265 points. Results from chi-square, and One Way Analysis of Variance showed that the association between education levels, and Business Skills Cognition was positive and significant. The article discusses the implication of these findings for education delivery and training for enterprise development in Kenya and any other society that is keen on the utilitarian values of education.

Abstract: Denitrification plays important roles in nitrogen cycling and management affecting both the environment and agricultural systems. Potential denitrification has a role in comparison of denitrification magnitudes in different soils. This paper discusses the concept of potential denitrification in relation to denitrification rate and conditions under which it is determined. The terminologies such as denitrification activity, intensity, capacity and potential are variously applied to describe denitrification rates, but the use of these terms is not consistent. Similarly, the concept of potential denitrification is variously espoused. Many researchers measure potential denitrification under entirely different conditions, and express the values in divergent units making meaningful comparisons between soils unfeasible. It is proposed that the concept of potential denitrification embraces the principle of maximum attainable denitrification rate under optimal conditions within the limitations of natural setting. T...

Abstract: The design and operation of flood management systems require computation of flood hydrographs for both design floods and flood forecasting purposes, since observed data are usually inadequate for these tasks. This is particularly relevant for most developing countries, i.e. mainly for tropical catchments. One possible way of obtaining information about flood hydrographs is through the use of rainfall—runoff models. Two such models, namely the Bochum model and the Nash Cascade—Diskin Infiltration model, which are semi-distributed and lumped models, respectively, were used in the present study. These models were applied to two catchments in Kenya with drainage areas of 6.71 km2 and 26.03 km2. A set of 13 selected rainfall—runoff events was used to calibrate and validate the models. The physical parameters required by the models were derived from catchment characteristics using GIS and remote sensing data while the conceptual parameters were obtained by optimization. The flood hydrographs simulated ...

Abstract: Between January and December 1999 the extent of biofilm development has been studied at two sites (muddy sediment site [A] and sandy sediment site [B]) in Njoro River, Kenya. Grain size, organic matter and bacterial abundance were determined at different depth layers of the sediment. Particulate carbohydrate concentrations were measured as an indicator of biofilm development in the sediment. Additionally, the development of the biofilm was investigated by placing glass slides at rock and sediment surfaces and in different sediment depth layers. Our first results for sediment samples collected in January 1999 and growth on slides exposed for 28 days in March 1999 is presented. Grain size analysis revealed that sediment particles < 1 mm contributed between 82 to 91% at site A and 45 to 67% at site B depending on the sediment layer. At site A, total organic matter (% weight loss on ignition) and total organic carbon (TOC) were more or less constant with depth while both parameters significantly decreased with depth at site B. Total organic nitrogen (TON) was detectable at all depth layers at site A but only in the top 40 mm layer at site B. Bacterial numbers were highest in the top 40 mm layer at both sites. Bacterial abundance of 3.95 ± 5.96 × 10 8 and 4.10 ± 3.88 x 10 8 cells g -1 dry sediment were recorded at site A and B, respectively. For both sites, highest concentrations of colloidal carbohydrates occurred in the top 40 mm layer, but concentrations were more or less constant below. Bacterial abundance on glass slides was higher on slides placed on rock surfaces than on fine sediment surfaces or within fine sediments.

Abstract: The effect of groundwater salinity and depth on soil salinity was investigated in a furrow-irrigated area of Kenya during consecutive wet and dry seasons. The groundwater salinity was significantly (P ≤ 0.05, R 2 = 0.75-0.88) related to soil salinity when the groundwater depth fluctuated within 0-1 m depth in both seasons. When the groundwater remained below 1 m, the relationship was not linear. This meant that when saline groundwater existed within 1 m from the soil surface, soil salinity ensued even when low salinity (electrical conductivity = 0.28 dS m -1 in the dry season) irrigation water was used. The depth of the groundwater table was different in each season. In general, deep levels occurred during the dry season while shallow water tables existed during the wet season. Thus, leaching of excess salts by rainwater was likely to be compounded by the shallow saline groundwater table and therefore not feasible if the saline groundwater table was <1 m regardless of season.

Abstract: (2003). Visitor Behaviors and Wildlife Impacts in Kenya: Perceptions of Wardens. Human Dimensions of Wildlife: Vol. 8, No. 2, pp. 159-160.