Department of Agricultural Resources and Economics
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Item Assessing the contribution of dolichos bean (Lablab purpureus L. (sweet)) to food security in a changing climate in Kenya(2022) Kamotho, Grace N.; Kinyua, Miriam G.; Muasya, Reuben M.Lablab pupureus (L.), is a multipurpose drought tolerant legume which is considered as a minor crop in Kenya, hence, it is underutilized. In Kenya there are few known Lablab genotypes for specific environments. Choice of genotypes to grow is based on colour preference and seed availability, thus low yields are obtained. To assess the status of Lablab production in Kenya, a baseline survey was conducted in Lablab growing localities. A disproportionate stratified sampling was used and a questionnaire was administered to 108 respondents from diverse Lablab growing regions of Kenya. Performance of Lablab genotypes under different environmental conditions was also evaluated. Field trials of forty five (45) accessions of Lablab collected from Rift Valley, Eastern, Coast and Central regions of Kenya were established in three locations with different agro-ecological environments; (Nakuru, Uasin Gishu and Bungoma). The 45 accessions and three environments were factorially combined and replicated three times in a randomized complete block design (RCBD). Results from the survey indicate that most farmers (84.3%) grew Lablab in small acreage of less than 1.0 acre, and only 44.4% of the respondents used the improved Lablab cultivars which were obtained from the Ministry of Agriculture or research stations. Majority (88%) preferred Lablab to common beans and all respondents noted that Lablab fetched more income per unit quantity than common bean. All respondents utilized Lablab dry beans as food. The crop was also utilized as a livestock feed especially during the dry season when no other crops are in the farms by 51.9% of the respondents while 25% used it in conservation agriculture and for soil erosion control. About 20.4% of farmers used the leaves and green pods as vegetables. The study identified accessions that are suitable for different agro ecological zones. In conclusion, Lablab is a crop that is climate resilient and contributes to food security in communities that grow it. It is recommended that dolichos should be promoted in Kenya as a climate change adaptation measure and for enhancing food security.Item Determination of the effect of fermentation on the rate of plant nutrient release from plant tissues.(2022) KAMOTHO, GRACE N.; MUNGA, ZACHARIA M.The use of fermented plant extracts (FPE) as a top dress in crop production is a natural process that can provide plant nutrients and suppress diseases. However, there is scanty information on the use of plant extracts and the bulky of it is not documented. This study aimed at determining the effectiveness of fermentation in extracting plant nutrients from plant tissues for use as top dress in crop production. Materials from Lantana (Lantana camara, L), stinging nettle (Urtica dioica L) and Tithonia (Tithonia diversifolia, G), common plants that are locally available in most agricultural areas were investigated. A complete randomized design (CRD) was used to set up the experiments in the laboratory. Tender shoots and leaves of these plants were fermented in water and the levels of nitrogen, phosphorous and potassium (NPK) contained were measured at intervals of 1, 5, 10, 15, 20 and 25 days. The concentration of lactic acid bacteria (LAB) yeasts and the pH were also determined at each interval. Standard foliar feeds (Agro-Feed and Power Booster) commonly used by farmers were used as control. The results demonstrated that Lantana and stinging nettle were not significantly different in the percentage of N released. Phosphorous was highest in stinging nettle at 5.26%, Tithonia had 5.12% while Lantana had the lowest at 4.48%. However, potassium was highest in Tithonia at 4.38%, stinging nettle had 3.64%, while Lantana had the lowest at 3.63%. There were also high significant differences in concentration of lactic acid bacteria (LAB), Yeast and pH at p<0.05. The findings of the study showed that nutrients can be extracted from plant materials by fermentation although in less quantities as compared to commercial foliar feeds.Item A community-based evaluation of population growth and agro-pastoralist resilience in Sub-Saharan drylands(2019-02) Burian, Alfred; Karaya, Rebecca; Julia, Wernersson; Egberth, Mikael; Lokorwa, Benjamin; Nyberg, GertAbstract Human population growth is considered together with climate warming as major driver of change in Sub-Saharan Africa. Research on the implications of increased population densities often utilises community knowledge but without incorporating the view of local stakeholders. In this study, we applied a community-centred approach to assess direct and indirect consequences of population growth in drylands of north-western Kenya. Combined social, agricultural and geo-spatial analyses allowed us to identify major system transitions, determine their linkage to population growth and deduce consequences for local livelihoods and community resilience. Community-members reported positive and negative consequences of fourfold population growth since 1974 but evaluated its overall effect as clearly beneficial. This overall positive effect was based on both, positive developments and the successful mitigation of potential system stressors. First, food security was maintained despite high growth rates because a shift from migratory pastoralism to a more labour-intensive agro-pastoralist system helped to increase agricultural productivity. Additionally, land-use changes were linked to land privatisation and improved erosion protection on private land, decoupling population growth from environmental degradation. We detected, however also early warning signs of reduced community resilience as households were unable to fully recover livestock densities after catastrophic events. A population-growth driven reduction in household land-sizes and the decreased monetary value of agricultural production were identified as drivers of this development. The extrapolation of our results to establish a general relationship between population densities, land-use and household resilience in Sub-Saharan drylands suggest that further system transformations will be required to ensure regional food-security.Item Optimization of manufacturing conditions of the new purple leafed Kenyan teas (TRFK 306) – maceration style and withering duration(2018) Kilel, E.C.; Wanyoko, J.K.; Faraj, A.K.; Ngoda, P.Purple tea in Kenya, TRFK 306, has received great attention due to its perceived health benefits though how it should be optimally manufactured has not been researched on exhaustively. The current study investigated on the two possible methods of manufacture – Cut Tear and Curl (CTC) and orthodox manufacture - with varying withering time of 0, 5, 10, 15 and 20 hours. Catechins, gallic acid, caffeine, total polyphenols and antioxidant activity were assayed as quality indicators. If gallic acid and caffeine are the main chemicals targeted, then orthodox type with longer withering, 15 – 20 hours, is usually recommended. When targeting catechins especially epigallocatechin gallate and high total polyphenols, orthodox type of manufacture whichever the withering time is proposed. CTC with withering hours of 15-20 produces teas with high antioxidant activity. It was concluded that TRFK 306 is best processed by orthodox or CTC but with longer withering time.Item Integrating Cordia Africana Trees on Farms Differentially Improves Soil Properties in Small Holder Farms in Kirinyaga County, Kenya(2023-08-08) Kamau, Miriam; Kinyanjui, Mwangi; Kamiri, HellenTree-based solutions are more efficient in nutrient cycling in farming systems and hence ideally suited for impoverished farmers experiencing food insecurity. Agroforestry trees have a positive effect on soil fertility through litter fall by the canopies compared to that of the adjacent open fields. Field sampling involved selecting mature Cordia africana trees from ten farms and collecting soil samples at varying distances from the tree trunks and at two depths (0-15 and 15-30cm). For each selected farm, soil samples were collected at three sampling points defined by distance from the tree base thus: - 5M (under the tree canopy), 11M (at the edge of the crown), and 30M (from the tree's influence. Laboratory analyses measured concentrations of nitrogen, phosphorus, potassium, calcium, magnesium, and organic carbon. The soil parameters investigated (Nitrogen, Phosphorus, Soil organic carbon, Potassium, and Calcium) were significantly higher in the topsoil than in the subsoil. The horizontal effect of trees with increasing distance from the tree on soil nitrogen, organic carbon, and phosphorus is minimal, the effect being more on vertical distribution (across depth). Differences in nutrient contents in soil nutrient variables between agroforestry and cropped land showed that soil nutrients within the Cordia africana system were higher than those under cultivated land implying that Cordia africana has a positive effect on soil quality. Thus, the study emphasizes the adoption of Cordia africana in agroforestry practices with a view to increase soil fertility and improve crop yields in sustainable farming. There is therefore need for the formulation of appropriate measures of soil management based on the characteristics of the sites.Item Salinity tolerance, growth and survival of three Artemia franciscana (Kellogg, 1906) populations under laboratory conditions(Wiley, 2024-04) Ngarari, Morine M.; Rugendo, Derrick G.; Nyonje, Betty M.; Hinzano, Sheban M.; Midumbi, David O.; Ngugi, Charles C.; Gatune, Charles W.In the 1980s, Artemia franciscana from San Francisco Bay (SFB) was introduced into Kenyan saltworks, where it has colonized and established stable populations. However, little is known about its biology, particularly with respect to its parental SFB population. This study compared the salinity tolerances of Kenyan (KEN) population, their SFB progenitors and those of Great Salt Lake (GSL) populations. Growth and survival of these A. franciscana populations were evaluated under varying salinity levels in a laboratory set up. A. franciscana nauplii were cultured at a rate of 1 nauplii/mL in 36 Erlenmeyer flasks and fed microalgae (Chaetoceros sp.) at 1.5 × 106 cells/animal/day for 8 days. Survival was evaluated daily and survivors were fixed in individual vials with Lugol solution. The total length of each fixed A. franciscana nauplii specimen was measured under a compound microscope. All populations were susceptible to salinities greater than 100 g/L. Compared with the parental SFB population, the KEN population exhibited significantly reduced survival and growth at 140 g/L, suggesting a narrower salinity tolerance range. These findings underscore the need for further studies focusing on other physiological parameters, abiotic factors and genetic characterization to confirm whether the KEN population is experiencing ecological adaptation. This will contribute to the optimization of Artemia practices in various salinity environments as a result of climate change.Item Farm Household Typology Based on Soil Quality and Influenced by Socio-Economic Characteristics and Fertility Management Practices in Eastern Kenya(2023-04-12) Wawire, Amos; Csorba, Ádám; Zein, Mohammed; Rotich, Brian; Phenson, Justine; Szegi, Tamás; Kovács, Eszter Tormáné; Michéli, ErikaThe smallholder farming systems in Sub-Saharan Africa (SSA) are highly diverse and heterogeneous in terms of biophysical and socio-economic characteristics. This study was conducted in upper Eastern Kenya (UEK) to categorize farm households and determine the influence of socio-economic characteristics (SeC) and soil fertility management practices (SFMP) on soil fertility across farms. Conditioned Latin hypercube sampling (cLHS) was performed to determine 69 soil sampling sites within Meru and Tharaka Nithi counties. From each household (whose field soil sample was obtained), data relating to resource endowment and soil fertility management were collected through a household questionnaire survey. Standard laboratory procedures were used to analyse soil samples. Data reduction was performed using categorical principal component analysis (CATPCA) (for SeC and SFMP) and standard principal component analysis (PCA) (for soil properties). Two-step cluster analysis identified three distinct farm categories or farm types (FT), namely, low fertility farms (FT1), moderately fertile farms (FT2), and fertile farms (FT3). The correlation of clusters against soil properties was significant across pH, soil organic carbon (SOC), cation exchange capacity (CEC), available P, plant available K, and exchangeable bases. FT1 had low SOC, pH, CEC and available P (soil characteristics), low usage of fertilizer and manure (soil fertility management), and smaller household size, lower income, and smaller farm size (socio-economic). FT2 had lower SOC (compared to FT3) and available P. In terms of soil fertility management, FT2 had higher cases of fallowing and composting with moderate fertilizer usage. Households in this category had moderate income, family size, and land size (socio-economic). FT3 had relatively high SOC, pH, CEC, and mineral nutrients. This farm type was characterized by high fertilizer use (soil fertility management) as well as larger household size, higher income, and larger farm size (socio-economic). The results indicate the importance of nutrient management in enhancing soil quality. Delineation and characterization of farms based on the various parameters including resource endowment reveal imbalanced farm resource flows, suggesting a need for locally tailored interventions suited for location-specific conditions to facilitate improved targeting of soil fertility-enhancing technologies and sustainable crop production regimes. While fertilizer is one of the most critical inputs for enhancing agricultural production, it is a major contributor to nitrous oxide emissions from agriculture and can have negative environmental effects on soil biota and water sources. Farmers’ knowledge on the use of fertilizer is thus necessary in developing strategies (such as integrated approach) to promote its efficient use and minimize its detrimental impacts.Item Enhancing Tripartite Symbiosis between Soybean, Bradyrhizobia and Arbuscular Mycorrhizal Fungiunder Contrasting Farm Management Practices in Tharaka-Nithi County-Kenya(Kenyatta University, 2021-05) Gitonga, Nicholas MawiraOrganic farming is gaining popularity as agronomically and environmentally sound soil management strategy with the potential to enhance soil microbial diversity and fertility, environmental quality and sustainable crop production. However, the role of bradyrhizobia and arbuscular mycorrhizal fungi (AMF) in organic farming systems is poorly understood. Field experiments were carried out to evaluate the effects of organic farming and bradyrhizobia inoculation on soybean nodulation, AMF root colonization, growth, production and yield quality. Greenhouse and laboratory experiments sought to determine the effects of bradyrhizobia and/or AMF inoculation and dual inoculation in promoting root colonization and nodulation, determine soil mycorrhizal inoculum potential (MIP), evaluate the abundance and effectiveness of native bradyrhizobia and determine the morphological and genetic diversity of native bradyrhizobia isolates under different farm management practices. Field experimental treatments included native bradyrhizobia, commercial Bradyrhizobiun japonicum, a mixture of native and commercial Bradyrhizobium japonicum and control. Promiscuous soybeans varieties SB 19 and SC squire as well as non-promiscuous Gazelle were used as test plants. All field experiments were carried out in split-split plot design. In the greenhouse, AMF and bradyrhizobia were inoculated and dual inoculated on SC squire soybeans. The AMF inoculants used were Funneliformis mosseae and Rhizophagus irregularis while bacteria involved commercial bradyrhizobia and native bradyrhizobia. Greenhouse experiments were set out using completely randomized design. The native bradyrhizobia were isolated and characterized. Deoxyribonucleic acid (DNA) from nodule isolates was extracted using Gene Jet DNA extraction kit. Polymerase chain reaction (PCR) targeting 16S rDNA gene was carried out using universal primers P5-R and P3-F. Polymerase chain reaction product purification and sequencing was carried out in MacrogenNetherlands. Sequencing was done using the same primers. Non molecular data obtained was analyzed using analysis of variance (ANOVA). Means that were significantly different at p< 0.05 were separated using Tukey’s HSD test. Field experiment results demonstrated significant improvement of soybean nodule dry weight (NDW), shoot dry weight (SDW) and seed dry weight (SEDW) due to inoculation. Bradyrhizobia inoculation increased soybean seed yields by between 29-59% of its potential yield. Remarkably, organic farming significantly (p=0.001) out-performed conventional systems in SDW, NDW, SEDW and AMF root colonization. Moreover, seed nutrient significantly differed in organic and conventional farming where, seed nitrogen, phosphorus, potassium and organic carbon were higher in organic farming. Soybean varieties differed significantly on SDW, NDW and SEDW, where SC squire performed better compared to SB 19 and Gazelle. Greenhouse results showed bradyrhizobia and AMF dual inoculation significantly enhanced AMF root colonization, NDW and SDW compared with individual bradyrhizobia, AMF or control. Moreover, organic farming significantly (p=0.001) increased SDW, NDW and AMF root colonization compared to conventional farming. Organic farming had a significant effect (p = 0.001) on soil MIP. Based on molecular analysis, isolates were bradyrhizobia and matched with Bradyrhizobium japonicum among other species. There was little or no genetic differentiation of isolates with the highest molecular variation (91.12%) within the populations and 8.88 % among populations. The results demonstrate the importance of organic farming and dual inoculation in sustainable crop production. The highly potential native bradyrhizobia isolates (GRPc and GRPk) and exotic AMF should be xix popularized and commercially ultilized by farmers to alleviate declining soil fertility and increase food production with minimum expenses.Item Effects of Blended Fertilizers on Leaf Nutrients Content of Mature Clonal Tea in Kenya. Journal of Experimental Research. Volume 6 (2).(Enugu State University of Science & Technology, 2018-06) itienei, Kibet S; Kamiri, Hellen W.; Kamau, David M.; Nyabundi, Wilson K.; Morogo, MaureenFertilizer studies in Kenya tea industry have focused predominantly on compound NPK. These fertilizers cannot be easily manipulated for specific soils and tea clones. In this respect, Athi River Mining limited has produced Mavuno blended NPK fertilizers with calcium (Ca) and magnesium (Mg). However, their application rates that would result in optimal nutrients uptake are lacking. This is the knowledge gap that this study sought to address. Therefore, the fertilizer blends were assessed for their effects on nutrients uptake at different rate in two sites. The sites were selected purposefully, one in the eastern and the other in the western tea growing areas. Randomized complete block design (RCBD) were used to select 36 trial plots in the two areas which were treated with three fertilizer types where one type was control, and four fertilizer application rates with one rate being a control. The trial was replicated three times Leaf samples were collected and analyzed for nutrients content. The data were then subjected to the analysis of variance (ANOVA) using Mstat C computer software package. Two leaves and a bud had higher nitrogen content (Timbilil 4.84%; Kagochi 4.53%) compared to deficient levels in mature leaf (Timbilil 2.26%; Kagochi 2.95%). This study has shown that supplementing the soil applied NPK fertilizers with calcium, magnesium and micronutrients resulted in better nutrients uptake.Item EFFECTS OF WEATHER ON THRIPS POPULATION DYNAMICS AND ITS IMPLICATIONS ON THE THRIPS PEST MANAGEMENT(Karatina University, 2008-06-30) Waiganjo, M.M.; Gitonga, L.M.; Mueke, J.M.Onion thrips, Thrips tabaci Lindeman, is the most destructive insect pest of the onion crop, Allium cepa L. worldwide. Both larvae and adults attack the onion crop at all stages of its growth, resulting in reduction of yield and quality. Despite the heavy losses incurred as a result of damage by the onion thrips, very little efforts have been made to develop an integrated pest management strategy for the control of the pest in many African countries. Field trials were conducted in four seasons at the Kenya Agricultural Research Institute (KARI) Mwea-Tebere farm in Kirinyaga District. Onion plants were planted periodically and thrips populations monitored weekly from onion plant samples and blue sticky traps for a full year under natural field conditions. The purpose of the trials was to assess the effect of weather on thrips population in onions with the aim of predicting thrips control requirements for a given climatic trend. Weather variables monitored included: rainfall, temperature, relative humidity and wind. Thrips occurred in the onion field and infested onions in all the crop seasons. However, there was significant (P=0.05) variation in thrips numbers between the crop seasons. Dry weather (30.3 mm rainfall) with moderately high temperatures (15.6-28.2oC) increased seasonal thrips numbers, while wet season (391mm rainfall) with moderately high relative humidity was negatively correlated with thrips numbers. Regression analysis (step-wise selection model) showed that minimum relative humidity was the only significant weather factor for predicting thrips infestation in the onion crop (R2 =0.15; y = 60.342-0.1022x). The results suggest that climatic trends can be used to determine the potential thrips control needs in onion production.