College of Agriculture & Natural Resources

Permanent URI for this collection

https://ir.knust.edu.gh/handle/123456789/7

Browse

Now showing 1 - 20 of 73

The Agronomic qualities of the Mexican Sunflower (Tithonia diversifolia) for soil fertility improvement in Ghana: an exploratory study
(2010) Partey, Samuel Tetteh
Soil fertility depletion remains a major biophysical constraint to increased food production in Ghana even when improved germplasm has been made available. With the growing concern of the potential of low input agriculture in mitigating soil fertility challenges, exploratory researches are imperative in selecting best quality organic materials that meet this expectation. This study was conducted to assess the suitability of Tithonia diversifolia green biomass as a nutrient source for smallholder agriculture in Ghana using both on-station and on-farm trials. The on-station research comprised an evaluation of the decomposition and nutrient release patterns of T. diversifolia in comparison with well-known leguminous species of agroforestry importance: Senna spectabilis, Gliricidia sepium, Leucaena leucocephala and Acacia auriculiformis. Concurrently, field trials were conducted to appraise the quality of T. diversifolia green biomass in relation to its biophysical effects on soil properties and the agronomic characteristics of crops. This was a comparative study with S. spectabilis, G. sepium and mineral fertilizer on a ferric acrisol. Field trials were also conducted to determine best practices for optimum biomass production of T. diversifolia using different pruning regimes and cutting heights as factors. The on-farm research was conducted at Dumasua in the Brong Ahafo Region of Ghana to appraise 200 farmers’ preliminary knowledge of T. diversifolia and evaluate the effect of T. diversifolia green biomass on soil fertility indicators and crop yields. The results of the decomposition study confirmed significantly high N, P, K concentrations in T. diversifolia comparable to levels recorded for the four leguminous species. In addition, T. diversifolia recorded the highest decomposition and nutrient release rates which differed significantly (p < 0.05) vii from rates of the four leguminous species. Although decomposition and nutrient release rates of species were related to quality of leaf material, P and Mg concentrations in particular were most influential in decomposition and nutrient release based on significant results. The on-station trials showed significant effect of the green manures (particularly T. diversifolia) on soil properties and the biomass and fruit yield of okro (Abelmoschus esculentus). These results were comparable and in some cases greater than fertilizer treatments. Total yield response in T. diversifolia treatment was 61% and 20% greater than the control and fertilizer treatments respectively. From the pruning experiment, it was evident that height of cutting, pruning frequency and their interaction significantly affected dry matter production of T. diversifolia. Dry matter production was highest (7.2 t ha-1yr-1) when T. diversifolia was pruned bi-monthly at 50 cm height. Results from the sociological survey confirmed farmers’ general knowledge on T. diversifolia at Dumasua was poor. Although majority of respondents had seen the plant growing, none could give a common name. Only the ornamental importance of T. diversifolia was identified. Meanwhile, the on-farm trials revealed a significant synergistic effect of combining T. diversifolia and fertilizer on soil nutrient availability and harvest index of maize. The results showed that the application of Tithonia either alone or in combination with fertilizer can increase yield by 24% and 54% respectively compared to plots which received no inputs.
An analysis of a peri-urban sanitation market and farmers’ perception on excreta reuse in agriculture in Dangme West District, Ghana
(MAY 2016) Nimoh, Fred
This study sought to analyse a peri-urban sanitation market and farmers’ perception on excreta reuse for agricultural purpose in Dangme West District of Ghana. Specifically, the study examined the constraints, motivations and strategies to the operation of sanitation business; analysed financing mechanisms and willingness-to-pay (WTP) for improved household latrines; investigated farmers’ perceptions toward excreta reuse for agricultural purpose; and reviewed literature on regulatory policies for sustainable sanitation. Data were collected using observations, interview guide and survey questionnaire. Descriptive and inferential statistics were used for data analysis and reporting. The motivations and constraints to sanitation business were examined using case sanitation service providers (SSPs). Budgetary estimates and the logit/logistic model were employed to analyse households’ latrine financing decisions, and their WTP for improved household latrines, using the contingent valuation method (CVM). Farmers’ perception on excreta reuse as fertilizer was analysed with a Likert-type scale and the ordered probit model. Results of the study showed that there exist various sanitation-related businesses such as latrine builders/masons, hardware suppliers and pit-emptiers, who operate as sole proprietors in a market characterized as monopolistic competition in the study area. Sanitation business in the study area was found to be profitable, despite the financial, institutional and social challenges to the SSPs’ business. The study found that a majority of the households practise open defecation (ODF), though they prefer improved latrines, particularly the flush latrine and ventilated improved pit (VIP) latrine. Lack of space and funds, availability of alternative option (beach) and no economic value for excreta were mentioned by the households as key considerations to owning a household latrine. A comparison of the households’ income and expenditure showed that the households have sufficient income to finance the construction and management of their latrines, contrary to the claim that they do not have funds to build a household latrine. A majority of households were willing to pay for improved latrines via savings rather than the use of credit, although the financial institutions in the study area are interested to offer loans for household latrines. Empirical results from the logistic model showed that there exists some relationship between households’ latrine financing decisions and their socioeconomic and community characteristics such as gender, education, household composition, income, tenancy, defecation practice and location of community. It was also found that a majority of farmers ‘disagree’ that excreta are a waste and they would use excreta as fertilizer if sterilised; as they ‘agree’ that excreta could pose health risks. Empirical results showed that a farmer’s decision to use excreta as fertilizer is more related to the perception on excreta as a resource, experience in community, household size, income, and land tenure system. Regulatory options identified for sustainable sanitation include the use of community-based organizations, the professional and trade associations, and consumers as 'watch groups'. Based on the findings of the study, the following recommendations, among others, have been made to help improve the Ghanaian peri-urban sanitation: there is the need to address the constraints to sanitation business for effective service delivery. Households should be encouraged to consider the ‘cheaper’ and more feasible latrine technologies, and also adopt joint-resource mobilization strategies for their latrines. Programmes aimed at promoting improved sanitation, in a sustainable manner, should consider the heterogeneous needs and location of households as well as the reuse potential of excreta in agriculture. The choice of regulatory options for sustainable sanitation should be based on a comparative assessment of the trade-offs between effectiveness, ease of implementation and costs and benefits.
An Analysis of Yam consumption Patterns in Ghanaian Urban Communities
(2009-07-14) Aidoo, Robert
This study examined the major factors that drive changes in yam consumption patterns across income groups, seasons and urban centers in Ghana to inform food policy formulation. The study, among other things, sought to provide evidence on whether or not yam had become a luxury food commodity in Ghanaian urban communities. Special attention was also given to the question of whether household income allocation between males and females had any significant effect on yam consumption. Quarterly household panel data collected from four urban centers were used to conduct a complete demand system analysis by employing the Almost Ideal Demand system (AIDS) and Quadratic Almost Ideal Demand System (QUAIDS) models through the use of the Ordinary Least Squares (OLS) method. The study estimated yam expenditure elasticities for the pooled/aggregate data and the four different urban centers across different income groups to test Engel’s law. Results of the study showed that majority (>80%) of yam consumers in Ghanaian urban communities preferred white yam to yellow and water yams, and the most important reason for their preference was taste. Boiled yam (ampesi) was the most preferred yam product in Ghanaian urban centers followed by pounded yam (fufu). Rice was identified as the most important substitute for yam in urban communities. In a typical Ghanaian urban center, household food budget formed about 51% of the total household budget. Yam constituted about 12% of household at-home food budget and 13% of its away-from-home food budget. The shares of food budget that households allocated to yam generally increased during the peak harvest season and dropped during lean season across all urban centers in Ghana. Yam expenditure elasticity for the pooled sample was found to be inelastic (0.76), suggesting that yam is a basic food commodity in a typical Ghanaian urban center. Yam expenditure elasticity was lowest for Tamale (0.64), a less urbanized center, and highest for Accra (1.01), a more urbanized center. Generally, across urban centers, the study supported Bennett’s law which posits that households switch from less to more expensive calorie consumption as their incomes increase. However, in each particular urban center, Engel’s law was affirmed; yam expenditure elasticity was higher for low-income households and lower for high-income households. Yam expenditure elasticity was found to vary across seasons; yam was expenditure elastic during the lean season and expenditure inelastic during the harvest season. Women’s share of household income was found to be positively related to household yam budget share. Evidence from this study did not support the hypothesis of economies of household size with respect to household yam budget share when the pooled data was used for analysis. However, the hypothesis of economies of household size was supported in the seasonal consumption analysis where households were found to enjoy economies of size during the relatively yam abundant period of August to December and diseconomies of size during the lean season. The study showed that yam budget share was own-price elastic but expenditure inelastic. Urban households were more responsive to changes in yam prices than changes in household income, implying that the substitution effect is stronger than the income effect. The high price elasticity for yam budget share stresses the importance of food price changes for households, and it is important that households’ reactions are taken into account in the development of comprehensive agricultural and food policies in Ghana. Based on the findings of the study, recommendations have been made to help improve the Ghanaian yam sector and household food security in urban centers.
Aspects of the ecology of noack’s roundleaf bat (Hipposideros Aff. Ruber) in Ghana
(2014-07-20) Nkrumah, Evans Ewald
The roost of bats in five caves in the central parts of Ghana were investigated. A total of 10,226 bats belonging to nine species were mist-netted within two years. There was a significant difference in species composition of the caves. The Noacks’s roundleaf bat, Hipposideros aff. ruber was found to be the most dominant species roosting inside the cave and some aspects of its ecology were further investigated. The flight activity of Hipposideros aff. ruber was limited to certain periods of the night at Kwamang cave one while it was uniform at Kwamang cave two. The estimated mean home range size of this species using radio-tracking was thirty-six hectares with a foraging range of 1.2 km. There was no significant difference in the home range sizes of the males and females. Hipposideros aff. ruber used 50% of its home range as the foraging area and 2% as the core area. Pregnant females had smaller home ranges and foraged not more than 0.2 km away from the roost cave. Hipposideros aff. ruber used all available habitats around its roost but strongly preferred to forage in fallow lands ahead of other habitats. This bat used tree farms such as cocoa as flight paths to commute between roost caves and foraging areas and exhibited a trimodal activity pattern foraging at dusk, midnight and dawn. Hipposideros aff. ruber is a strong flyer commuting over longer distances. A three kilometre radius around its roost should be included in the protection of its home range. In highly impacted agricultural landscapes, fallow lands are recommended as conservation units to support this bat. In such landscapes, provision of canopy trees as flight paths is recommended to allow them to commute between roost and habitats that support higher prey densities
Aspects of the ecology of Noack’s roundleaf bat (Hipposideros Aff. Ruber) in Ghana
(2014-07-27) Ewald Nkrumah, Evans
The roost of bats in five caves in the central parts of Ghana were investigated. A total of 10,226 bats belonging to nine species were mist-netted within two years. There was a significant difference in species composition of the caves. The Noacks’s roundleaf bat, Hipposideros aff. ruber was found to be the most dominant species roosting inside the cave and some aspects of its ecology were further investigated. The flight activity of Hipposideros aff. ruber was limited to certain periods of the night at Kwamang cave one while it was uniform at Kwamang cave two. The estimated mean home range size of this species using radio-tracking was thirty-six hectares with a foraging range of 1.2 km. There was no significant difference in the home range sizes of the males and females. Hipposideros aff. ruber used 50% of its home range as the foraging area and 2% as the core area. Pregnant females had smaller home ranges and foraged not more than 0.2 km away from the roost cave. Hipposideros aff. ruber used all available habitats around its roost but strongly preferred to forage in fallow lands ahead of other habitats. This bat used tree farms such as cocoa as flight paths to commute between roost caves and foraging areas and exhibited a trimodal activity pattern foraging at dusk, midnight and dawn. Hipposideros aff. ruber is a strong flyer commuting over longer distances. A three kilometre radius around its roost should be included in the protection of its home range. In highly impacted agricultural landscapes, fallow lands are recommended as conservation units to support this bat. In such landscapes, provision of canopy trees as flight paths is recommended to allow them to commute between roost and habitats that support higher prey densities.
Assessing the Effectiveness of Native Rhizobia as Potential Strains for Local Inoculant Production for Enhanced Cowpea and Groundnut Yields in Northern Ghana
(October, 2018) Osei, Ophelia
Efficient exploration of the legume-rhizobium symbiosis via inoculation with rhizobia is constrained by the limited knowledge on the fate of introduced strains under field conditions and the unavailability of effective native strains for use as local inoculants. This research therefore sought to address these challenges in four studies: i) nodule occupancy determination ii) identification of effective native isolates iii) symbiotic performance evaluation of elite native isolates under field conditions and iv) assessment of the persistence of elite isolates following field inoculation. Significant differences (p< 0.05) in shoot biomass of cowpea following inoculation was observed. The differences were explained via nodule occupancy studies by designing specific primers for the test strain Bradyrhizobium pachyrhizi BR 3262 (a recommended cowpea strain in Brazil) using the comparative genomics approach. Out of eleven specific primer pairs designed, the primers 2645 and 2736 were observed to be highly sensitive and reliably detected the target strains in nodules extracts of gnotobiotic system and potted soil grown cowpea. These two primers are thus novel tools for determining the fate of BR 3262 in field inoculation studies. The approach for designing specific primers in this study should be applicable to other bacteria/rhizobium strains whose genomic sequences are available. Bioprospecting for nodules of groundnut and cowpea cultivated in farmers’ fields without inoculation was done followed by isolation of rhizobium in the laboratory. Authentication and symbiotic effectiveness evaluation of the isolated rhizobium strains led to the selection of seven effective isolates. The nitrogen accumulated via BNF of the selected effective isolates was significantly higher (p< 0.05) compared to the –N control treatment. Treatment with isolate KNUST 1002 resulted in a total N accumulation that was comparable to the reference strain 32H1 on groundnut (BR 1 variety) grown in potted soils. Genetic characterization of the seven effective isolates revealed them as diverse with isolates KNUST 1003 and KNUST 1007 belonging to the Rhizobium tropici speices. The five remaining isolates were identified to belong to the Bradyrhizobium yuanmingense species. The two most effective isolates were evaluated in the field alongside a positive (with nitrogen) and negative (without nitrogen or inoculation) control on cowpea (Songotra variety) and groundnut (Chinese variety) in multi-locational trials in the Northern region of Ghana using the randomized complete block design. On the average, cowpea grain yields produced by the inoculated treatments were significantly (p< 0.05) larger than the –N treatment. Isolate KNUST 1002 produced the best average yield (1056 kg ha-1 ) which was significantly different from the other treatments. Groundnut yields on the other hand were significantly larger with isolate KNUST 1006 (1234 kg ha-1 ). The chemical properties of soils in the study locations generally showed low soil fertility. The different soil types significantly influenced the performance of treatments across the study locations. Twenty-six and 23% of the variability in grain yields of cowpea and groundnut respectively, was explained by the soil type and treatment interaction. These results imply that effective native isolates in this study can improve grain yields of cowpea and groundnut based on location specific recommendations. The persistence of effective isolates following previous inoculation on cowpea and groundnut was assessed in the 2017 cropping season on ten of the sites considered in 2016. Nodulation in both previously inoculated and re-inoculated plots were significantly higher than the un-inoculated plots (+N and –N). Nodule dry mass recorded for isolate KNUST 1006 in previously inoculated plots did not differ significantly from that of re-inoculated plots on both target host. However, the nodule dry mass recorded for isolate KNUST 1002 on cowpea in previously inoculated plots was significantly lower than in re-inoculated plots. Increases in grain yield of groundnut were significantly larger for treatment with isolate KNUST 1006 than the other treatments for previously inoculated and re-inoculated plots. Isolate KNUST 1002 on cowpea produced significantly higher yields than the other treatments in previously inoculated and re-inoculated plots. The type of legume host in each case influenced the performance of the isolates. There were no significant differences in the yields produced by either of the isolates in previously inoculated and re-inoculated plots. These results indicate that effective native isolates persisted and effectively nodulated the target legumes obviating the need for re-inoculation in subsequent cropping season. The outcomes of these studies have important implications for the use of effective isolates from this study as inoculants to improve cowpea and groundnut yields particularly in Northern Ghana.
Assessing the effectiveness of native Rhizobia as potential strains for local inoculant production for enhanced cowpea and groundnut yields in northern Ghana
(October, 2018) Osei, Ophelia
Efficient exploration of the legume-rhizobium symbiosis via inoculation with rhizobia is constrained by the limited knowledge on the fate of introduced strains under field conditions and the unavailability of effective native strains for use as local inoculants. This research therefore sought to address these challenges in four studies: i) nodule occupancy determination ii) identification of effective native isolates iii) symbiotic performance evaluation of elite native isolates under field conditions and iv) assessment of the persistence of elite isolates following field inoculation. Significant differences (p< 0.05) in shoot biomass of cowpea following inoculation was observed. The differences were explained via nodule occupancy studies by designing specific primers for the test strain Bradyrhizobium pachyrhizi BR 3262 (a recommended cowpea strain in Brazil) using the comparative genomics approach. Out of eleven specific primer pairs designed, the primers 2645 and 2736 were observed to be highly sensitive and reliably detected the target strains in nodules extracts of gnotobiotic system and potted soil grown cowpea. These two primers are thus novel tools for determining the fate of BR 3262 in field inoculation studies. The approach for designing specific primers in this study should be applicable to other bacteria/rhizobium strains whose genomic sequences are available. Bioprospecting for nodules of groundnut and cowpea cultivated in farmers’ fields without inoculation was done followed by isolation of rhizobium in the laboratory. Authentication and symbiotic effectiveness evaluation of the isolated rhizobium strains led to the selection of seven effective isolates. The nitrogen accumulated via BNF of the selected effective isolates was significantly higher (p< 0.05) compared to the –N control treatment. Treatment with isolate KNUST 1002 resulted in a total N accumulation that was comparable to the reference strain 32H1 on groundnut (BR 1 variety) grown in potted soils. Genetic characterization of the seven effective isolates revealed them as diverse with isolates KNUST 1003 and KNUST 1007 belonging to the Rhizobium tropici speices. The five remaining isolates were identified to belong to the Bradyrhizobium yuanmingense species. The two most effective isolates were evaluated in the field alongside a positive (with nitrogen) and negative (without nitrogen or inoculation) control on cowpea (Songotra variety) and groundnut (Chinese variety) in multi-locational trials in the Northern region of Ghana using the randomized complete block design. On the average, cowpea grain yields produced by the inoculated treatments were significantly (p< 0.05) larger than the –N treatment. Isolate KNUST 1002 produced the best average yield (1056 kg ha-1) which was significantly different from the other treatments. Groundnut yields on the other hand were significantly larger with isolate KNUST 1006 (1234 kg ha-1). The chemical properties of soils in the study locations generally showed low soil fertility. The different soil types significantly influenced the performance of treatments across the study locations. Twenty-six and 23% of the variability in grain yields of cowpea and groundnut respectively, was explained by the soil type and treatment interaction. These results imply that effective native isolates in this study can improve grain yields of cowpea and groundnut based on location specific recommendations. The persistence of effective isolates following previous inoculation on cowpea and groundnut was assessed in the 2017 cropping season on ten of the sites considered in 2016. Nodulation in both previously inoculated and re-inoculated plots were significantly higher than the un-inoculated plots (+N and –N). Nodule dry mass recorded for isolate KNUST 1006 in previously inoculated plots did not differ significantly from that of re-inoculated plots on both target host. However, the nodule dry mass recorded for isolate KNUST 1002 on cowpea in previously inoculated plots was significantly lower than in re-inoculated plots. Increases in grain yield of groundnut were significantly larger for treatment with isolate KNUST 1006 than the other treatments for previously inoculated and re-inoculated plots. Isolate KNUST 1002 on cowpea produced significantly higher yields than the other treatments in previously inoculated and re-inoculated plots. The type of legume host in each case influenced the performance of the isolates. There were no significant differences in the yields produced by either of the isolates in previously inoculated and re-inoculated plots. These results indicate that effective native isolates persisted and effectively nodulated the target legumes obviating the need for re-inoculation in subsequent cropping season. The outcomes of these studies have important implications for the use of effective isolates from this study as inoculants to improve cowpea and groundnut yields particularly in Northern Ghana.
Assessing the potential options for improving crop yield and water use efficiency in the sahelian low input millet-based cropping system
(2015-11-09) Ali, Ibrahim
Soil amendments are often unavailable in adequate quantities for increased crop production in the Sahelian smallholder cereal cropping systems. In order to increase crop yields and encourage farmers to apply inorganic fertilizers, fertilizer micro-dosing technology was developed. This technology has given promising results in respect of crop yields improvement, fertilizer use efficiency and economic returns. However, many scientific reports have cautioned that crop nutrients uptake under micro-dosing technology could be markedly greater than what was applied through the technology. There, is therefore, an urgent need for critical assessment of the potential mining effect of fertilizer micro-dosing in order to develop supportive strategies for further improvement of the efficient use of limited resources of smallholder farmers. The objectives of this study were to (1) explore the mechanisms governing the growth enhancing phenomena of the fertilizer micro-dosing technology, (2) assess the potential effects of integrated use of organic amendments and fertilizer micro-dosing in improving millet yield and water use efficiency and (3) evaluate the extent of nutrient gains and losses under fertilizer micro-dosing by estimating the associated nutrient balances. To achieve these objectives, three field experiments were conducted in Niger during the 2013 and 2014 rainy seasons. The first experiment comprised two options of fertilizer micro-doing (2 g DAP hill-1 and 6 g NPK hill-1) with the broadcast of 200 kg NPK ha-1 which is the blanket recommended rate of fertilizer in the study area. The second experiment consisted of the factorial combination of two fertilizer micro-dosing options with three rates of manure (1000 kg ha-1, 2000 kg ha-1 and 3000 kg ha-1) and method of their applications (hill placement and broadcasting). The third experiment involved two fertilizer micro-dosing options and three organic mulches (millet straw, Acacia tumida pruning and manure). The most important findings that emerged from these experiments were that growth parameters (leaf area index, leaf chlorophyll content and root length density) were markedly increased with fertilizer micro-dosing at the early stage of millet growth compared with the broadcast of 200 kg NPK ha-1. The millet grain yield under fertilizer micro-dosing combined with manure increased on average by 59%, 83% and 113% for 1000 kg ha-1, 2000 kg ha-1 and 3000 kg ha-1 of manure inputs, respectively in comparison with fertilizer micro-dosing alone. These increases in grain yield were accompanied by marked increases in water use efficiency. Hill placement of manure increased total dry matter on average by 23% and water use efficiency by 35% relative to that of manure broadcasting. The partial nutrient balances were -37 kg N ha-1yr-1, -1 kg P ha-1yr-1, -34 kg K ha-1yr-1 in plots that received the application of 2 g DAP hill-1 and -31 kg N ha-1yr-1, -1 kg P ha-1yr-1, -27 kg K ha-1yr-1 for the 6 g NPK hill-1 treatment. The partial nutrient balances were exacerbated by the nutrient export in straw yields which accounted for on average 66% N, 55% P and 89% K of total export. The annual full nutrient balances with fertilizer micro-dosing treatments were on average - 47 kg N ha-1 yr-1, -7 kg P ha-1 yr-1 and -22 kg K ha-1 yr-1 which represented 7%, 24% and 10% of N, P and K stocks, respectively. Combined application of fertilizer micro-dosing with organic mulch increased millet grain yield by 37%. The millet grain yield increases relative to the un-mulched control were 51% for manure, 46% for A. tumida mulch and 36% for millet mulch. The addition of A. tumida pruning, manure and millet straw mulch to fertilizer micro-dosing increased water use efficiency of millet by on average 55%, 49% and 25%, respectively. These results indicate that the positive effect of fertilizer micro-dosing in increasing millet yield results from the better exploitation of soil nutrients due to early lateral roots proliferation within the topsoil. In addition, millet production with the fertilizer micro-dosing technology can be improved further by hill-placement of manure. However, the increase in yields with fertilizer micro-dosing was accompanied by an increase in soil nutrients uptake which resulted in negative nutrient balances. These results have important implications for developing an agro-ecological approach to address sustainable food production in the Sahelian smallholder cropping systems.
Assessment of environmental impacts of cage aquaculture on Lake Volta of Ghana
(June, 2016) Karikari, Anthony Yaw
In recent years, tilapia cage farming has become important aspect of commercial fish production in Lake Volta and the number of the cage culture establishments (now 467) continues to expand in the multipurpose lake. Cage farms release nutrients that can cause pollution to water and sediment quality. However, there is paucity of information on the impact of cage culture on the lake’s environment. Consequently, a study was conducted from August 2013 to April 2015 at two fish farms in the Lake Volta to assess the potential impact of cage culture on the environment of the lake. The study utilized four methods. The first was through structured questionnaire to gather information on the cage farms. The second method used physico-chemical analyses of water and sediment following standard procedures. The third method considered mass balance model to estimate the amount of nutrients discharged from the cage farms into the environment. The fourth method used Dillo n Rigler phosphorus mass balance model for the prediction of ecological carrying capacities of two selected farm areas in the lake. The results from the questionnaire survey on the cage farms revealed that only large scale farmers have adequate environmental awareness and therefore monitor the water and sediment quality in their farm areas. The study on the nutrient waste emission from the cages indicated that 64.8–68.1 % of C, 72.0–75.8 % of N, and 81.0–84.7 % of P of the total feed input were released into the lake’s environment for each tonne of fish produced, and only 31.9–35.0 % of C, 24.2–28.3 % of N and 15.3–19.2 % of P were harvested as fish biomass. Despite the large discharges of particulate and dissolved nutrients estimated by the mass balance models, physico-chemical water quality parameters including dissolved inorganic nutrients (NO3-N, NO2-N, NH4-N and PO4-P), chlorophyll-a varied temporally and showed no significant differences between the fish farm sites and the reference sites (ANOVA, p > 0.05). The low impact of the cage aquaculture could be attributed to the nutrient losses through the outflow at the dam which was 43.56 km 3 per annum (i.e about one-third of the lake’s volume); dispersion of iv the wastes by water currents, consumption of waste by schools of wild fish species found around the fish cages and also by dilution. Sediment analysis revealed the sediment texture of all monitoring sites to be sandy clay loam with moderate impact on sediment quality with respect to organic matter. The total organic carbon (TOC), total organic matter (TOM), and total nitrogen (TN) content in the sediment under the cages were significantly lower than those of the reference sites (ANOVA, p<0.05). The results showed that concentrations of heavy metals in the water column and sediments were low and within the range of tolerable levels for the lake ecosystem. The estimated ecological capacities were from 3,697 to 4,621 ty -1 for Farm A and from 28,322 to 33,042 ty -1 for Farm B zones. The estimated ranges of values are higher than the present production in the zones. This suggests that more cage culture of tilapia could be established in the lake without compromising the water quality and the ecosystem. However, water quality monitoring should be undertaken periodically to accurately determine the current state of the lake in order to both confirm and refine predictions, and ensure sustainable cage culture development in Lake Volta. Overall, the water quality indices (CCME-QI and GWQI) carried out indicted that the lake water is good and suitable for tilapia production and other ecosystem uses such as irrigation, recreation and water supply
Bio-oil Production from Lignocellulosic Biomass using fast Pyrolysis in a Fluidized-Bed Reactor
(2015-04-20) Hensley Duku, Moses
This study focused on bio-oil production from lignocellulosic biomass using fast pyrolysis in a fluidized-bed reactor as a substitute or replacement energy source to reduce the dependence on imported and expensive fossil fuels for transportation and stationary engines applications. Seven major lignocellulosic biomass, mostly agricultural crop residues (i.e. corn cobs and its straw, rice straw and its husk, sugarcane bagasse and cocoa pod husk) and wood processing residue (Triplochiton scleroxylon sawdust) were characterized using proximate, ultimate, chemical and x-ray fluorescence analyses. Fast pyrolysis was carried out in a pilot-scale fluidized-bed reactor to investigate the effect of temperature on product distribution, i.e. bio-oil, char and non-condensable gas yields. This was followed by characterization of the bio-oils obtained for fuel properties using physical and ultimate analyses. Based on the results obtained, a scheme was proposed for bio-oil production. The proximate analysis gave moisture contents (MCs) of 9.15 and 10.29 %wt. respectively for the corn stalk and cocoa pod husk and high volatile matter contents of 79.48, 80.48 and 80.72 %wt. respectively for the sugarcane bagasse, corn cobs and wawa sawdust. The XRF analysis gave high silica contents of 16.30 and 22.38%wt. for the rice husk and its straw respectively. Ultimate analysis gave carbon contents of 42.65, 43.32 and 43.87 %wt. respectively for the corn stalk and its cobs as well as cocoa pod husk and oxygen contents of 59.00 and 66.57 %wt. respectively for the rice husk and its straw. Wawa sawdust, sugarcane bagasse and corn residues performed well in both the proximate and ultimate analyses, giving carbon contents of 44. 0 %wt and volatile content of 75.0 – 80.74 %wt and fixed carbon content of 7.60 – 12.01 %wt., while wawa sawdust, sugarcane bagasse and cocoa pod husk gave the lowest ash contents during the XRF analysis. Sulphur levels were, however, below 1.0 %wt. for all the biomass samples, while nitrogen levels were 1.49 and 2.23 %wt. respectively for the corn stalk and cocoa pod husks. Chemical analysis gave cellulose contents of 43.82 and 44.40 %wt. respectively for the corn stalk and wawa sawdust, hemicellulose content of 46.59 %wt. for the corn cobs and high lignin content of 41.08 %wt. for the rice husk. The highest HHV of 18.61 MJkg-1 was recorded for the wawa sawdust. During the biomass fast pyrolysis, bio-oil yields increased from 53.0 to 60.0 %wt. for the rice straw as the temperature increased from 400 to 500 oC and then reduced to 50.3 %wt. at 700 oC. The non-condensable gas yields increased from 8.2 to 32.5 %wt. while bio-char yields decreased from 38.6 to 17.2 %wt. as the temperature increased from 400 to 700 oC. Similar trends in product distribution were obtained for other biomass samples. Maximum bio-oil yields ranged from 53.0 to 66.0 %wt. respectively at 550 oC for the cocoa pod husk and corn stalk. The high yield of bio-oil at high temperatures was due to primary iv reactions, such as decomposition of cellulose and hemicellulose which resulted in the bio-oil production. At temperatures above 500oC, chemical reactions involving mainly the decomposition of lignin and secondary reactions involving the breakdown of the bio-oils resulted in high yields of bio-char. Characterization of the bio-oils obtained gave a pH ranging from 2.1 to 3.2 respectively for the wawa sawdust and corn stalk bio-oils, compared to a pH of 5.6 for light petroleum diesel oil. The high pH of the bio-oils makes them highly acidic, and thus corrosive, which is a problem. Carbon contents were 41.70 and 65.68 %wt. respectively for bio-oils obtained from the rice husk and its straw, lower than those of fossil diesel fuels. The highest MC of 26.7 %wt. was recorded for the cocoa pod husk bio-oils compared to very low MCs in light petroleum and heavy fuel oils. The HHVs, which ranged from 16.80 to 23.30 MJkg-1 respectively for the corn cobs and sugarcane bagasse bio-oils were lower than those of light petroleum oil (40.0 MJkg-1) and heavy fuel oil (40.0 MJkg-1). These results indicate that the bio-oils obtained had lower fuel properties than fossil fuels. The low sulphur and nitrogen levels indicate, however, that low SO2 and NO2 would be expected to be emitted during combustion. The bio-oils can, however, be upgraded by hydrodeoxygenation which, reduces the oxygen content and thus the acidity. Of all the biomass samples characterized, the corn stalk, corn cob, wawa sawdust and sugarcane bagasse samples performed the best for bio-oil production due to their high carbon, cellulose and volatile matter contents as well as HHVs and produced the highest bio-oil yields. The cocoa pod husk and rice husk, however, performed the least due probably to high silica, low carbon and cellulose contents. Slight differences in maximum bio-oil yields obtained and trends of the other product yields may be due to differences in proximate, ultimate and chemical compositions of the biomass samples. This work would have significant economic and environmental benefits since it would reduce the dependence on imported and expensive fossil fuels for transportation and stationary engine applications. The proposed scheme could result in cost-effective bio-oil production at both the national and international levels at a low production cost since lignocellulosic biomass is cheap and fast pyrolysis is also a cheap process.
Bio-oil production from Lignocellulosic biomass using fast pyrolysis in a fluidized-bed reactor
(2015-02-10) Duku, Moses Hensley
This study focused on bio-oil production from lignocellulosic biomass using fast pyrolysis in a fluidized-bed reactor as a substitute or replacement energy source to reduce the dependence on imported and expensive fossil fuels for transportation and stationary engines applications. Seven major lignocellulosic biomass, mostly agricultural crop residues (i.e. corn cobs and its straw, rice straw and its husk, sugarcane bagasse and cocoa pod husk) and wood processing residue (Triplochiton scleroxylon sawdust) were characterized using proximate, ultimate, chemical and x-ray fluorescence analyses. Fast pyrolysis was carried out in a pilot-scale fluidized-bed reactor to investigate the effect of temperature on product distribution, i.e. bio-oil, char and non-condensable gas yields. This was followed by characterization of the bio-oils obtained for fuel properties using physical and ultimate analyses. Based on the results obtained, a scheme was proposed for bio-oil production. The proximate analysis gave moisture contents (MCs) of 9.15 and 10.29 %wt. respectively for the corn stalk and cocoa pod husk and high volatile matter contents of 79.48, 80.48 and 80.72 %wt. respectively for the sugarcane bagasse, corn cobs and wawa sawdust. The XRF analysis gave high silica contents of 16.30 and 22.38%wt. for the rice husk and its straw respectively. Ultimate analysis gave carbon contents of 42.65, 43.32 and 43.87 %wt. respectively for the corn stalk and its cobs as well as cocoa pod husk and oxygen contents of 59.00 and 66.57 %wt. respectively for the rice husk and its straw. Wawa sawdust, sugarcane bagasse and corn residues performed well in both the proximate and ultimate analyses, giving carbon contents of 44. 0 %wt and volatile content of 75.0 – 80.74 %wt and fixed carbon content of 7.60 – 12.01 %wt., while wawa sawdust, sugarcane bagasse and cocoa pod husk gave the lowest ash contents during the XRF analysis. Sulphur levels were, however, below 1.0 %wt. for all the biomass samples, while nitrogen levels were 1.49 and 2.23 %wt. respectively for the corn stalk and cocoa pod husks. Chemical analysis gave cellulose contents of 43.82 and 44.40 %wt. respectively for the corn stalk and wawa sawdust, hemicellulose content of 46.59 %wt. for the corn cobs and high lignin content of 41.08 %wt. for the rice husk. The highest HHV of 18.61 MJkg-1 was recorded for the wawa sawdust. During the biomass fast pyrolysis, bio-oil yields increased from 53.0 to 60.0 %wt. for the rice straw as the temperature increased from 400 to 500 oC and then reduced to 50.3 %wt. at 700 oC. The non-condensable gas yields increased from 8.2 to 32.5 %wt. while bio-char yields decreased from 38.6 to 17.2 %wt. as the temperature increased from 400 to 700 oC. Similar trends in product distribution were obtained for other biomass samples. Maximum bio-oil yields ranged from 53.0 to 66.0 %wt. respectively at 550 oC for the cocoa pod husk and corn stalk. The high yield of bio-oil at high temperatures was due to primary iv reactions, such as decomposition of cellulose and hemicellulose which resulted in the bio-oil production. At temperatures above 500oC, chemical reactions involving mainly the decomposition of lignin and secondary reactions involving the breakdown of the bio-oils resulted in high yields of bio-char. Characterization of the bio-oils obtained gave a pH ranging from 2.1 to 3.2 respectively for the wawa sawdust and corn stalk bio-oils, compared to a pH of 5.6 for light petroleum diesel oil. The high pH of the bio-oils makes them highly acidic, and thus corrosive, which is a problem. Carbon contents were 41.70 and 65.68 %wt. respectively for bio-oils obtained from the rice husk and its straw, lower than those of fossil diesel fuels. The highest MC of 26.7 %wt. was recorded for the cocoa pod husk bio-oils compared to very low MCs in light petroleum and heavy fuel oils. The HHVs, which ranged from 16.80 to 23.30 MJkg-1 respectively for the corn cobs and sugarcane bagasse bio-oils were lower than those of light petroleum oil (40.0 MJkg-1) and heavy fuel oil (40.0 MJkg-1). These results indicate that the bio-oils obtained had lower fuel properties than fossil fuels. The low sulphur and nitrogen levels indicate, however, that low SO2 and NO2 would be expected to be emitted during combustion. The bio-oils can, however, be upgraded by hydrodeoxygenation which, reduces the oxygen content and thus the acidity. Of all the biomass samples characterized, the corn stalk, corn cob, wawa sawdust and sugarcane bagasse samples performed the best for bio-oil production due to their high carbon, cellulose and volatile matter contents as well as HHVs and produced the highest bio-oil yields. The cocoa pod husk and rice husk, however, performed the least due probably to high silica, low carbon and cellulose contents. Slight differences in maximum bio-oil yields obtained and trends of the other product yields may be due to differences in proximate, ultimate and chemical compositions of the biomass samples. This work would have significant economic and environmental benefits since it would reduce the dependence on imported and expensive fossil fuels for transportation and stationary engine applications. The proposed scheme could result in cost-effective bio-oil production at both the national and international levels at a low production cost since lignocellulosic biomass is cheap and fast pyrolysis is also a cheap process.
The changing nature of work and the state of labour standards in Ghana
(2014) Osei, Hannah Vivian
The state of employment within countries and the world at large is of considerable importance to both governments and international organisations. In recent years, the nature of work has become flexible and insecured. The juxtaposition of the two apparently contrary targets, flexibility and security, raises concern...
Compatibility of Jatropha Curcas in an Agroforestry System
(2011-12-04) Abugre, Simon
Jatropha curcas is gaining importance as a potential biofuel crop in Ghana. Already skeptics are talking about the impact of the crop on food crops. It is important that the compatibility of J. curcas in agroforestry systems is investigated to provide answers to some of the potential problems being advanced. Experiments were conducted to determine the compatibility of J. curcas on the growth and yield performance of Zea mays. To determine the growth and yield of Z. mays under J. curcas hedgerows, an experiment using a Randomized Complete Block Design (RCBD) with three hedgerow spacings of 2 m x 1 m, 3 m x 1 m, 4 m x 1 m of J. curcas and a control (No hedgerow) was conducted. This was replicated 3 times. The results of the study showed that J. curcas spacing had no significant effect (P ≥ 0.05) on plant height, plant diameter, number of leaves and number of nodes/plant of maize in the first year. In the second year, however, increases in plant height of 17.19%, 22.39% and 23.38% were realized for 3 m x 1 m, 4 m x 1 m and the control (No hedgerow) respectively with respect to 2 m x 1 m. Diameter at first node however, increased by 19.69%, 16.87% and 18.46% for control, 3 m x 1 m and 4 m x 1 m respectively with respect to 2 m x 1 m. Maximum grain yield of maize was 4.47 tons/ha in the first year at the control treatment, which differed significantly from the 2 m x 1 m, 3 m x 1 m, 4 m x 1 m treatments. Chemical properties of the soil did not record any significant decline after two years of cultivation for pH, organic carbon, total nitrogen, organic matter, exchangeable cations, total exchangeable bases, exchangeable acids and base saturation. The highest Land Equivalent Ratio (LER) was recorded at 4 m x 1 m for both years, making it the most suitable plant spacing for J. curcas with maize while the highest economic returns were obtained at 4m x 1m and 3m x 1m spacing. The influence of storage period, fertilizer and spacing on the growth and yield of J. curcas propagated from seed were evaluated in a second experiment using two different designs. Seeds of J. curcas were stored for 1 to 12 months, sown on beds in a RCBD, replicated four times and their viability and germination energy tested. The results showed a progressive decline in germination from 98% after one month to 52% when stored for 12 months. The highest germination energy was obtained during the first two months of storage. Fertilizer and spacing effects were also evaluated in a split plot design in RCBD and replicated three times. Three plant spacings (D1=1m x 1m; D2=2m x 1m; D3=3m x 1m) and two fertilizer application levels (F0: 0kgNPK/ha, F1: 150kgNPK/ha) were used. Fertilizer and spacing interaction did not significantly (P ≥ 0.05) affect yield components of J. curcas. The fertilizer treatment however, had a significant effect on yield components and increased seed and fruit yield by 56.4% and 51.75% respectively. Spacing did not significantly affect seed yield. A third experiment on the variation in seed sources of J. curcas and polybag size on the growth of seedlings was laid out using a split plot design in RCBD with 3 replicates. The results showed significant variation in seed weight from the various seed sources but no differences in seed length and seed width. Seedling growth of J. curcas was highest when larger polybag size was used, however, it did not differ significantly from medium polybag size. Based on the results obtained medium polybag size would be ideal for raising seedlings. In a fourth experiment the decomposition trend of J. curcas leaves was assessed by placing 80 g fresh leaves in a 0.30 m x 0.30 m nylon litter decomposition bags of 2 mm mesh size under closed and open canopies. The total quantity of litter produced in a year at different spacings were 2.27 ton/ha, 1.10 tons/ha and 0.79 tons/ha for 1 m x 1m, 2 m x 1m and 3 m x 1m, respectively. The month of November had the highest litter fall (508.8 kg/ha) for 1 m x 1 m. J. curcas under open canopy had 97-99% of leaf litter decomposing by the end of the experimental period and a half-life of 25 days. Open canopy had the highest decomposition constant (k) of 0.020. In a final experiment the effect of aqueous extracts from leaves and roots of J. curcas on four traditional crops (Phaseolus vulgaris, Zea mais, Lycopersicon lycopersicum and Abelmoschus esculentus was examined. Aqueous extracts at concentrations of 2%, 4%, 6%, 8% and 10% applied to the test crops affected all the crops. Extracts at higher concentrations of J. curcas had a strong inhibitory effect on germination, radicle and plumule length of all the test crops. The inhibitory effect suggests the presence of allelochemicals that could inhibit the growth of the crops. Generally, it can be concluded that J. curcas is compatible with maize in an alley cropping system but closer spacing of planting J. curcas can reduce maize yields. Management practices such as pruning could be applied to get the optimum benefit from the system.
Compatibility of Jatropha Curcas in an Agroforestry System
(2015-04-20) Abugre, Simon
Jatropha curcas is gaining importance as a potential biofuel crop in Ghana. Already skeptics are talking about the impact of the crop on food crops. It is important that the compatibility of J. curcas in agroforestry systems is investigated to provide answers to some of the potential problems being advanced. Experiments were conducted to determine the compatibility of J. curcas on the growth and yield performance of Zea mays. To determine the growth and yield of Z. mays under J. curcas hedgerows, an experiment using a Randomized Complete Block Design (RCBD) with three hedgerow spacings of 2 m x 1 m, 3 m x 1 m, 4 m x 1 m of J. curcas and a control (No hedgerow) was conducted. This was replicated 3 times. The results of the study showed that J. curcas spacing had no significant effect (P ≥ 0.05) on plant height, plant diameter, number of leaves and number of nodes/plant of maize in the first year. In the second year, however, increases in plant height of 17.19%, 22.39% and 23.38% were realized for 3 m x 1 m, 4 m x 1 m and the control (No hedgerow) respectively with respect to 2 m x 1 m. Diameter at first node however, increased by 19.69%, 16.87% and 18.46% for control, 3 m x 1 m and 4 m x 1 m respectively with respect to 2 m x 1 m. Maximum grain yield of maize was 4.47 tons/ha in the first year at the control treatment, which differed significantly from the 2 m x 1 m, 3 m x 1 m, 4 m x 1 m treatments. Chemical properties of the soil did not record any significant decline after two years of cultivation for pH, organic carbon, total nitrogen, organic matter, exchangeable cations, total exchangeable bases, exchangeable acids and base saturation. The highest Land Equivalent Ratio (LER) was recorded at 4 m x 1 m for both years, making it the most suitable plant spacing for J. curcas with maize while the highest economic returns were obtained at 4m x 1m and 3m x 1m spacing. The influence of storage period, fertilizer and spacing on the growth and yield of J. curcas propagated from seed were evaluated in a second experiment using two different designs. Seeds of J. curcas were stored for 1 to 12 months, sown on beds in a RCBD,replicated four times and their viability and germination energy tested. The results showed a progressive decline in germination from 98% after one month to 52% when stored for 12 months. The highest germination energy was obtained during the first two months of storage. Fertilizer and spacing effects were also evaluated in a split plot design in RCBD and replicated three times. Three plant spacings (D1=1m x 1m; D2=2m x 1m; D3=3m x 1m) and two fertilizer application levels (F0: 0kgNPK/ha, F1: 150kgNPK/ha) were used. Fertilizer and spacing interaction did not significantly (P ≥ 0.05) affect yield components of J. curcas. The fertilizer treatment however, had a significant effect on yield components and increased seed and fruit yield by 56.4% and 51.75% respectively. Spacing did not significantly affect seed yield. A third experiment on the variation in seed sources of J. curcas and polybag size on the growth of seedlings was laid out using a split plot design in RCBD with 3 replicates. The results showed significant variation in seed weight from the various seed sources but no differences in seed length and seed width. Seedling growth of J. curcas was highest when larger polybag size was used, however, it did not differ significantly from medium polybag size. Based on the results obtained medium polybag size would be ideal for raising seedlings. In a fourth experiment the decomposition trend of J. curcas leaves was assessed by placing 80 g fresh leaves in a 0.30 m x 0.30 m nylon litter decomposition bags of 2 mm mesh size under closed and open canopies. The total quantity of litter produced in a year at different spacings were 2.27 ton/ha, 1.10 tons/ha and 0.79 tons/ha for 1 m x 1m, 2 m x 1m and 3 m x 1m, respectively. The month of November had the highest litter fall (508.8 kg/ha) for 1 m x 1 m. J. curcas under open canopy had 97-99% of leaf litter decomposing by the end of the experimental period and a half-life of 25 days. Open canopy had the highest decomposition constant (k) of 0.020. In a final experiment the effect of aqueous extracts from leaves and roots of J. curcas on four traditional crops (Phaseolus vulgaris, Zea mais, Lycopersicon lycopersicum and Abelmoschus esculentus was examined. Aqueousextracts at concentrations of 2%, 4%, 6%, 8% and 10% applied to the test crops affected all the crops. Extracts at higher concentrations of J. curcas had a strong inhibitory effect on germination, radicle and plumule length of all the test crops. The inhibitory effect suggests the presence of allelochemicals that could inhibit the growth of the crops. Generally, it can be concluded that J. curcas is compatible with maize in an alley cropping system but closer spacing of planting J. curcas can reduce maize yields. Management practices such as pruning could be applied to get the optimum benefit from the system.
Compatibility of Jatropha Curcas in anAgroforestry System
(2015-05-22) Abugre, Simon
Jatropha curcas is gaining importance as a potential biofuel crop in Ghana. Already skeptics are talking about the impact of the crop on food crops. It is important that the compatibility of J. curcas in agroforestry systems is investigated to provide answers to some of the potential problems being advanced. Experiments were conducted to determine the compatibility of J. curcas on the growth and yield performance of Zea mays. To determine the growth and yield of Z. mays under J. curcas hedgerows, an experiment using a Randomized Complete Block Design (RCBD) with three hedgerow spacings of 2 m x 1 m, 3 m x 1 m, 4 m x 1 m of J. curcas and a control (No hedgerow) was conducted. This was replicated 3 times. The results of the study showed that J. curcas spacing had no significant effect (P ≥ 0.05) on plant height, plant diameter, number of leaves and number of nodes/plant of maize in the first year. In the second year, however, increases in plant height of 17.19%, 22.39% and 23.38% were realized for 3 m x 1 m, 4 m x 1 m and the control (No hedgerow) respectively with respect to 2 m x 1 m. Diameter at first node however, increased by 19.69%, 16.87% and 18.46% for control, 3 m x 1 m and 4 m x 1 m respectively with respect to 2 m x 1 m. Maximum grain yield of maize was 4.47 tons/ha in the first year at the control treatment, which differed significantly from the 2 m x 1 m, 3 m x 1 m, 4 m x 1 m treatments. Chemical properties of the soil did not record any significant decline after two years of cultivation for pH, organic carbon, total nitrogen, organic matter, exchangeable cations, total exchangeable bases, exchangeable acids and base saturation. The highest Land Equivalent Ratio (LER) was recorded at 4 m x 1 m for both years, making it the most suitable plant spacing for J. curcas with maize while the highest economic returns were obtained at 4m x 1m and 3m x 1m spacing. The influence of storage period, fertilizer and spacing on the growth and yield of J. curcas propagated from seed were evaluated in a second experiment using two different designs. Seeds of J. curcas were stored for 1 to 12 months, sown on beds in a RCBD, iv replicated four times and their viability and germination energy tested. The results showed a progressive decline in germination from 98% after one month to 52% when stored for 12 months. The highest germination energy was obtained during the first two months of storage. Fertilizer and spacing effects were also evaluated in a split plot design in RCBD and replicated three times. Three plant spacings (D1=1m x 1m; D2=2m x 1m; D3=3m x 1m) and two fertilizer application levels (F0: 0kgNPK/ha, F1: 150kgNPK/ha) were used. Fertilizer and spacing interaction did not significantly (P ≥ 0.05) affect yield components of J. curcas. The fertilizer treatment however, had a significant effect on yield components and increased seed and fruit yield by 56.4% and 51.75% respectively. Spacing did not significantly affect seed yield. A third experiment on the variation in seed sources of J. curcas and polybag size on the growth of seedlings was laid out using a split plot design in RCBD with 3 replicates. The results showed significant variation in seed weight from the various seed sources but no differences in seed length and seed width. Seedling growth of J. curcas was highest when larger polybag size was used, however, it did not differ significantly from medium polybag size. Based on the results obtained medium polybag size would be ideal for raising seedlings. In a fourth experiment the decomposition trend of J. curcas leaves was assessed by placing 80 g fresh leaves in a 0.30 m x 0.30 m nylon litter decomposition bags of 2 mm mesh size under closed and open canopies. The total quantity of litter produced in a year at different spacings were 2.27 ton/ha, 1.10 tons/ha and 0.79 tons/ha for 1 m x 1m, 2 m x 1m and 3 m x 1m, respectively. The month of November had the highest litter fall (508.8 kg/ha) for 1 m x 1 m. J. curcas under open canopy had 97-99% of leaf litter decomposing by the end of the experimental period and a half-life of 25 days. Open canopy had the highest decomposition constant (k) of 0.020. In a final experiment the effect of aqueous extracts from leaves and roots of J. curcas on four traditional crops (Phaseolus vulgaris, Zea mais, Lycopersicon lycopersicum and Abelmoschus esculentus was examined. Aqueous v extracts at concentrations of 2%, 4%, 6%, 8% and 10% applied to the test crops affected all the crops. Extracts at higher concentrations of J. curcas had a strong inhibitory effect on germination, radicle and plumule length of all the test crops. The inhibitory effect suggests the presence of allelochemicals that could inhibit the growth of the crops. Generally, it can be concluded that J. curcas is compatible with maize in an alley cropping system but closer spacing of planting J. curcas can reduce maize yields. Management practices such as pruning could be applied to get the optimum benefit from the system.
Constraints to growth of street food enterprises in Ghana and effects of targeted business interventions on performance
(2016) Mensah, James Osei
The aim of this study was to the determine constraints to the growth of street food enterprises in Ghana and examine the effects of targeted business management interventions on the practices and performance of these firms. Specifically, the study sought to determine the factors that influence vendors’ decision to participate in business management intervention in the form of training. Also, attention was given to effects of only standard business management training (treatment 1) on business practices and performance of vendors as well as the effects of a combined intervention of standard business management training and training on street food vendors’ association (treatment 2). Lastly, the study analysed the extent of heterogeneity of the effects of above interventions and whether the effects of treatment 1 and treatment 2 on business practices and performance are significantly different. Data from a randomized field experiment of a freely offered business management course among 516 street food vendors in Kumasi and Tamale metropolises of Ghana were used to achieve the study objectives. Ordinary Least Squares (OLS) regression models were used to estimate whether vendors’ self-reported business constraints actually limit business growth whilst probit model was used to analyse determinants of participation in training interventions respectively. Difference-in-differences and instrumental variable analyses were used to estimate Intention to Treat (ITT) and Average Treatment Effect on the Treated (ATET) respectively. Descriptive analyses show that the street food sector is dominated by women with little or no formal education. Based on vendors’ self-reported constraints to business growth, high cost of production, limited access to credit, input price variability, inadequate knowledge in business management and limited access to reliable electricity (power) were ranked as the five most critical constraints. Results of OLS analyses also found inadequate managerial skills and financial constraints as the two most critical constraints to growth of street food enterprises, thus confirming assessment based on vendors’ perception. The study found formal education, the presence of trusted hands in the business and financial performance of firms to have a significant positive effect on probability of participation whilst vendors’ involvement in other economic activity (aside food vending), distance from vending premises to training centre and location of vendor significantly decreased probability of participation. Combined treatment of business management training and training on formation and management of vendors’ organization (Treatment 2) had statistically significant positive effect of 40.6% on the overall business practices index whilst record management index increased by 39.5%. Effects of this treatment on business practices were found to be heterogeneous. The study however did not find any significant effects on business performance of treated enterprises although treated vendors with high education experience a 10% increase in gross margin ratio. Treatment 1 (only business management training) on the other hand neither led to any significant improvement in business practices nor performance. The study explained the differences between effects of treatment 1 and 2 by the effects of extra module of formation and management of street food vendors’ organization on collective action parameters such as organizational membership, membership commitment and cooperation with other vendors to pursue mutually beneficial goals. Although these parameters may not directly affect vendors’ implementation of standard business management practices, they offered committed and cooperating members the platform and an opportunity for either further discussions among vendors on the training content or refresher training from external resource persons at virtually no fees. The study makes several recommendations to improve performance and regulation of the street food sector and also guide the design and implementation of future training programmes.
Conversion of Natural Forest to Cocoa Agroforest in Lowland Humid Ghana: Impact on Plant Biomass Production, Organic Carbon and Nutrient Dynamics
(2009) Dawoe, Evans
This study was conducted to assess the effects of forest conversion to shaded-cocoa system on plant biomass, nutrient fluxes and soil physico-chemical properties along a chronosequence (forest, 3, 15 and 30-year-old cocoa farms) in the Moist Semi-deciduous Forest Zone of the Ashanti Region, Ghana. It also explored farmer indigenous knowledge and perceptions of soils and soil fertility dynamic processes. Plant biomass and above-ground organic carbon and nutrient pools significantly declined following changes in land-use compared to soil pools. Tree biomass constituted the largest pool ranging from 12.7 ±1.6 Mg ha-1 for the 3-year-old cocoa system to 209.3±33.3 Mg ha-1 in the forest. Soil Organic Carbon (SOC) in 0-60 cm soil depth did not change significantly over a 30-year period and ranged from 49.0±2.3 to 67.4±1.1 Mg C ha-1 in 3 year-old shaded cocoa system and forest respectively. SOC significantly declined only in the top (0-10 cm) soil at 3 years after conversion but recovered at 15 years. Thirty-year-old shaded-cocoa systems yielded up to 151 Mg C ha-1 primarily stored in established trees (both cocoa and shade trees) and soil pools. Total N declined only in the 10-20 cm soil depth in 3 and 15 year-old treatments but remained stable in all other soil depths across the chronosequence while available P stocks declined significantly. Soil exchangeable Ca, K and Mg stocks remained relatively stable with a tendency to improve, and cation exchange capacity (CEC) and base saturation increased more or less along the chronosequence. Soil bulk density (gm cm-3) increased significantly with increasing age of plantation only for the top 0-10 cm soil layer but did not differ among sites for similar depths. Despite the apparent stability of soil C stocks and nutrients (0-60 cm) along the chronosequence, soil quality declined under cocoa land-use at 3 years. Microbial biomass demonstrated a strong seasonal variation. However, conversion of forest did not result in a significant decline in microbial biomass. Mean annual litterfall and stand litterstocks differed significantly among land-uses. Litterfall ranged from 5.0 Mg ha-1 in 3-year-old cocoa to 10.4 Mg ha-1 forest systems while stand litterstocks were from 3.6 to 5.9 Mg ha-1 in 3 and 15-year-old farms respectively. Annual decomposition coefficients (kL) were similar in cocoa systems (0.221-0.227) but greater under forests (0.354). Estimated nutrient inputs from litterfall was 4 to 165 kg ha-1yr-1 of P and Ca respectively in 15-year-old and forest plots respectively. Turnover of fine roots was 3,591, 1,427, 2,466 and 4,066 kg ha-1yr-1 for forest, 3, 15 and 30-year-old plots respectively. Nutrient inputs through turnover of fine roots were estimated to be 16-31 kg N ha–1year–1, 2 -5 kg P ha–1year–1, 9-36 kg K ha–1 year–1, 18-47 kg Ca ha–1year–1 and 3-25 kg Mg ha–1year–1 across the chronosequence. There were significant differences in incident rainfall, throughfall and stemflow chemistry. Mean annual inputs of nutrients fluxes in incident rainfall were 5.7 kg N, 0.14 kg P, 13.6 kg K, 9.43 kg Ca and 5.6 kg Mg ha-1 yr-1. Rainfall loading or net canopy exchange was negative for total N at all sites while concentrations of P and the basic cations increased in throughfall relative to incident rainfall. Throughfall on average constituted about 95% of the total solute inputs of rainfall origin to forest floor. The mean N and P input-output balances were negative showing the system’s ‘no external input’ character. Farmers in the study had a well-developed knowledge system of their soils and related fertility processes. They derived their knowledge from observable plant and soil characteristics namely; soil color, crop yield, water retention capacity, difficulty to work soil, type and abundance of indicator weeds, leaf color or deficiency symptoms observed on crops and presence and abundance of soil macro-fauna. The qualitative perceptions of farmers matched scientific assessment of fertile or infertile soils. The results suggest the integration of local and scientific knowledge to facilitate the processes for formulating policies and development plans for agriculture truly participatory, gender sensitive and collaborative approaches. Enhancement farmers’ capability to adopt improved farm management and land preparation methods is required to conserve the soil and sustain long-term productivity.
Conversion of Natural Forest to Cocoa Agroforest in Lowland Humid Ghana: Impact on Plant Biomass Production, Organic Carbon and Nutrient Dynamics
(2009-07-14) Dawoe, Evans
This study was conducted to assess the effects of forest conversion to shaded-cocoa system on plant biomass, nutrient fluxes and soil physico-chemical properties along a chronosequence (forest, 3, 15 and 30-year-old cocoa farms) in the Moist Semi-deciduous Forest Zone of the Ashanti Region, Ghana. It also explored farmer indigenous knowledge and perceptions of soils and soil fertility dynamic processes. Plant biomass and above-ground organic carbon and nutrient pools significantly declined following changes in land-use compared to soil pools. Tree biomass constituted the largest pool ranging from 12.7 ±1.6 Mg ha-1 for the 3-year-old cocoa system to 209.3±33.3 Mg ha-1 in the forest. Soil Organic Carbon (SOC) in 0-60 cm soil depth did not change significantly over a 30-year period and ranged from 49.0±2.3 to 67.4±1.1 Mg C ha-1 in 3 year-old shaded cocoa system and forest respectively. SOC significantly declined only in the top (0-10 cm) soil at 3 years after conversion but recovered at 15 years. Thirty-year-old shaded-cocoa systems yielded up to 151 Mg C ha-1 primarily stored in established trees (both cocoa and shade trees) and soil pools. Total N declined only in the 10-20 cm soil depth in 3 and 15 year-old treatments but remained stable in all other soil depths across the chronosequence while available P stocks declined significantly. Soil exchangeable Ca, K and Mg stocks remained relatively stable with a tendency to improve, and cation exchange capacity (CEC) and base saturation increased more or less along the chronosequence. Soil bulk density (gm cm-3) increased significantly with increasing age of plantation only for the top 0-10 cm soil layer but did not differ among sites for similar depths. Despite the apparent stability of soil C stocks and nutrients (0-60 cm) along the chronosequence, soil quality declined under cocoa land-use at 3 years. Microbial biomass demonstrated a strong seasonal variation. However, conversion of forest did not result in a significant decline in microbial biomass. Mean annual litterfall and stand litterstocks differed significantly among land-uses. Litterfall ranged from 5.0 Mg ha-1 in 3-year-old cocoa to 10.4 Mg ha-1 forest systems while stand litterstocks were from 3.6 to 5.9 Mg ha-1 in 3 and 15-year-old farms respectively. Annual decomposition coefficients (kL) were similar in cocoa systems (0.221-0.227) but greater under forests (0.354). Estimated nutrient inputs from litterfall was 4 to 165 kg ha-1yr-1 of P and Ca respectively in 15-year-old and forest plots respectively. Turnover of fine roots was 3,591, 1,427, 2,466 and 4,066 kg ha-1yr-1 for forest, 3, 15 and 30-year-old plots respectively. Nutrient inputs through turnover of fine roots were estimated to be 16-31 kg N ha–1year–1, 2 -5 kg P ha–1year–1, 9-36 kg K ha–1 year–1, 18-47 kg Ca ha–1year–1 and 3-25 kg Mg ha–1year–1 across the chronosequence. There were significant differences in incident rainfall, throughfall and stemflow chemistry. Mean annual inputs of nutrients fluxes in incident rainfall were 5.7 kg N, 0.14 kg P, 13.6 kg K, 9.43 kg Ca and 5.6 kg Mg ha-1 yr-1. Rainfall loading or net canopy exchange was negative for total N at all sites while concentrations of P and the basic cations increased in throughfall relative to incident rainfall. Throughfall on average constituted about 95% of the total solute inputs of rainfall origin to forest floor. The mean N and P input-output balances were negative showing the system’s ‘no external input’ character. Farmers in the study had a well-developed knowledge system of their soils and related fertility processes. They derived their knowledge from observable plant and soil characteristics namely; soil color, crop yield, water retention capacity, difficulty to work soil, type and abundance of indicator weeds, leaf color or deficiency symptoms observed on crops and presence and abundance of soil macro-fauna. The qualitative perceptions of farmers matched scientific assessment of fertile or infertile soils. The results suggest the integration of local and scientific knowledge to facilitate the processes for formulating policies and development plans for agriculture truly participatory, gender sensitive and collaborative approaches. Enhancement farmers’ capability to adopt improved farm management and land preparation methods is required to conserve the soil and sustain long-term productivity.
Densification of Sawdust of Tropical Hardwoods and Maize Cobs at Room Temperature Using Low Compacting Pressure Without a Binder
(2015-05-22) Mitchual, Stephen Jobson
This dissertation reports the findings of densifying maize cobs and sawdust of six selected tropical hardwood timber species at room temperature (25oC) using low compacting pressure (CP) varied from 10 MPa to 50 MPa, without a binder. The maize cobs was crushed using a hammer mill. Particle size 1mm or less of the maize cobs was used for the study. Sawdust of the six timber species were sun dried and graded into particle sizes (P): P ≤ 1 mm, 1 mm < P ≤ 2 mm and 2 mm < P ≤ 3.35 mm. Briquettes were produced using a laboratory hydraulic press and a piston. Physical and mechanical characteristics of briquettes determined were briquettes' stability, relaxed density, compressive strength (CS) in cleft, impact resistance index (IRI) and water resistance (WR) quality. Additionally, some physico-chemical and thermal properties of the biomass materials used for the study were determined. The study revealed that at 5% level of significance the density of timber species used for the study had significant negative correlation with CS in cleft, IRI and WR quality of briquettes produced. Furthermore, species density significantly and positively correlated with relaxed density of briquettes produced. Generally, species, particle size and CP had significant effect on stability in length and diameter, relaxed density, CS in cleft, IRI and WR quality of briquettes produced (p-value < 5%). Linear regression models established between the research factors and dependent variables suggested that species density, particle size and CP were good predictors of stability in length and diameter, relaxed density, CS in cleft, IRI and WR quality of briquettes produced. The multiple correlation coefficient (R) and adjusted R2 for the regression models ranged from 0.74 - 0.93 and 0.54 - 0.87 respectively with p-values less than 5%. The result further indicated that mixing sawdust of C. pentandra with P. africana or T. superba significantly improved upon the CS in cleft, IRI and WR quality of briquettes 6 produced. The mixing ratio of the sawdust also had significant effect on the mechanical and physical properties of the briquettes produced. The study further revealed that briquettes produced from maize cobs at low CP and room temperature had low CS in cleft, IRI and WR quality. However, these properties were significantly improved when maize cobs was combined with sawdust of C. pentandra, T. superba and P. africana. The gross calorific values of the six hardwood timber species were adequate and they ranged from 20.16 to 22.22 MJ/kg. The biomass materials used for the study were also found to be environmentally friendly since they contained low amount of nitrogen, sulphur and ash content. From this study it could be concluded that briquettes with adequate physical and mechanical properties could be produced from sawdust of tropical hardwood species and their mixture at room temperature using low CP. Additionally, briquettes with adequate physical and mechanical characteristics could be produced from maize cobs at room temperature using low CP when maize cobs particles are combined with sawdust of Ceiba pentandra. These findings could enhance the existing technology for densifying sawdust and maize cobs, especially in the rural communities.
Domestication of the shea (vitellaria paradoxa c.f. gaertn) tree: developing improved propagation techniques for accelerated plant growth.
(2015-11-08) Yeboah, Julius
The shea (Vitellaria paradoxa Gaertn) tree which grows wild is a multi – purpose species highly valued for oil obtained from its seed which is similar to that of cocoa butter. The wild nature of the shea tree, slow growth and long gestation period does not make its development attractive thus hampering its domestication. However, worldwide, vegetative propagation methods have been used as a means for domesticating endangered and wild species which will give a promising future to the shea industry. A series of field and laboratory experiments were carried out at the Cocoa Research Institute Sub-station, Bole and KNUST, Kumasi from 2012 to 2014. The objectives of the study were to (i) assess the rooting performance of air-layered stems under dry and wet conditions (ii) determine the effect of propagating structures and seedling types on the weaning and field survival of rooted propagules (iii) assess the role of some endogenous growth promoting substances and application of some exogenous growth regulators on rooting of air-layered stems (iv) investigate the physiological and environmental effects of scions and rootstocks on grafting success (v) study the biochemical constituents and anatomical features of shoots and rootstocks used for grafting, layering and rooted cuttings . A series of factorial experiments in randomized complete block design were used for the field studies. The data were analyzed using Analysis of Variance (ANOVA), regression and correlation analysis. Rooting of the air-layered shoots was better in both number and length of the roots with the application of 10,000 ppm indolebutyric acid and using Sphagmum moss as rooting medium than the other treatments. Ambient low temperatures (22-24 o C) had significant positive effect on rooting of air-layered shoots. Weaning of propagules showed high survival for the rooted cuttings in the mist propagator (93.3 %) comparable to that of the seedlings (100 %). Plant height and stem girth of the rooted cuttings were however similar for all the propagating structures during the weaning period of three months. In comparison with the normal (seedling) plantlet, the rooted cuttings vii in the mist propagator recorded better growth in terms of leaf production, plant height and stem girth. There was a significant relationship between the canopy architecture of the selected tree and the root production of the layered shoots expressed as Y (rooting) = 113.87 -23.697 X (canopy spread); R 2 = 0.89; P < 0.002; n = 9. There was also a significant relationship between field survival of propagules and the month of establishment expressed as Y (percent survival) = -2844 + 0.070 X (month); p < 0.001; R 2 = 0.68; n = 90. For field establishment, planting at a soil depth of 52 cm was suitable for transplanting weaned propagules as it produced the highest survival, biggest girth and highest number of leaves. Biochemical studies on stem portions showed the presence of nitrogen, protein, simple sugars, total free phenols and auxins which played very significant role in vegetative propagation (air-layering, cuttings and grafting) in producing high rooting and graft success. Anatomical studies revealed that some growth hormones and medium promoted cell differentiation (vascular tissues, xylem, cambium and phloem) in the shoots to enhance rooting. The best wounding method on scions to yield significant graft success and enhanced growth was pre-curing whilst rejuvenated shoot was preferred to young plants as root stocks. Grafting using the top cleft technique with partially sprouted scions significantly gave the best graft success. Coppicing trees in May/June produced the highest number of shoots within sixty days after coppicing as well as the highest graft success. Stages of wound healing and graft union formation were also revealed through the anatomy (differentiation of the xylem phloem and cambial tissues) of the grafts which were indicative of compatibility or incompatibility. Conclusions of the study indicate that the top cleft grafting technique results in the highest graft success.

Browse

Browsing College of Agriculture & Natural Resources by Title

Results Per Page

Sort Options