College of Agriculture & Natural Resources

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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
(KNUST, 2016-05) 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 pitemptiers, 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 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
Assessment of environmental impacts of cage aquaculture on Lake Volta of Ghana
(KNUST, 2016-06) Karikari, Anthony Yaw
Abstract 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 Dillon 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 km3 per annum (i.e about one-third of the lake’s volume); dispersion of 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.
ASSESSMENT OF TONO AND VEA RESERVOIRS FOR SUSTAINABLE NILE TILAPIA (Oreochromis niloticus) CAGE AQUACULTURE DEVELOPMENT IN UPPER EAST REGION, GHANA
(KNUST, 2019-06) AGBEKO. ETORNYO
The use of man-made aquatic ecosystems such as reservoirs and dugouts originally built for water supply, irrigation and fish farming is an emerging trend in most developing countries. Most reservoirs are being assessed for their potential for cage fish culture as a result of the high demand of fish. Northern Ghana has a number of reservoirs and dugouts which were originally constructed to conserve water for irrigated farming particularly the Tono and Vea reservoirs, however they seem to be under-utilized. This study was conducted to evaluate the potential of cage aquaculture on the reservoirs by assessment of the water quality, suitable zones, carrying capacity (CC) and development of aquaculture management areas (AMAs) within two major reservoirs in Upper East Region (UER) namely; Tono and Vea reservoirs. These reservoirs were monitored using linear stratified sampling technique and monthly sampling of eighteen water quality variables between 06:00 to 10:00 for fifteen months (February 2015 to April 2016). Three replicates of samples were obtained for each variable from each stratum of the reservoir. Water temperature, water depth, transparency, pH and conductivity were measured in-situ using combined portable meters. Water sampling and laboratory analysis were based on standard analytical methods for examination of water and waste-water. Temporal and spatial dynamics of the reservoirs were investigated using multivariate statistical methods to obtain three seasonality regimes from the water quality with total variance in both reservoirs < 88.5%. Water quality in both reservoirs could support Nile tilapia culture (temperature between 26.730 ⁰C, dissolved oxygen > 5 mg l-1 , average water depth > 3 m but < 10 m, pH was slightly acidic to slightly alkaline). Geographical information system-based spatial multi-criteria analysis results indicate that 3.85 km2 (39.05% suitability) and 2.15 km2 (68.40% suitability) of reservoir area were suitable for the development of cage aquaculture in Tono and Vea reservoirs, respectively. Estimates of carrying capacity i.e. production, physical, ecological, and social were integrated to obtain the final aquaculture CC of 719.40 m-3 and 65.55 m-3 as production volume for Tono and Vea reservoirs, respectively. Results for trophic level index (TLI) indicate that Tono reservoir has very high nutrient enriched waters (TLI: 5.23; super trophic), whiles Vea reservoir has high nutrient enriched waters (TLI: 4.32; eutrophic). Based on the trophic status, percentage allocation of aquaculture CC and other secondary data; the three AMAs in Tono reservoir and the five AMAs in Vea reservoir could produce 107.91 and 9.83 metric tones of cultured Nile tilapia per production cycle respectively. The study postulate that the ecosystem approach to aquaculture could be pragmatic stepwise approach that has salient potential to deal with environmental, economic and social issues associated with cage culture in Tono and Vea reservoirs. Best management practices (BMPs), physical and biosecurity measures are needed to minimize aquatic animal health risk. The use of CC based suitable zones and identification of individual AMAs are recommended as useful for decision-making by fisheries and aquaculture regulators, managers of reservoirs and other aquaculture policy-makers for sustainable cage aquaculture in the two reservoirs.
Assessment of Tono and Vea Reservoirs for Sustainable Nile Tilapia (Oreochromis Niloticus) Cage Aquaculture Development in Upper East Region, Ghana
(2019-06) Etornyo Agbeko
The use of man-made aquatic ecosystems such as reservoirs and dugouts originally built for water supply, irrigation and fish farming is an emerging trend in most developing countries. Most reservoirs are being assessed for their potential for cage fish culture as a result of the high demand of fish. Northern Ghana has a number of reservoirs and dugouts which were originally constructed to conserve water for irrigated farming particularly the Tono and Vea reservoirs, however they seem to be under-utilized. This study was conducted to evaluate the potential of cage aquaculture on the reservoirs by assessment of the water quality, suitable zones, carrying capacity (CC) and development of aquaculture management areas (AMAs) within two major reservoirs in Upper East Region (UER) namely; Tono and Vea reservoirs. These reservoirs were monitored using linear stratified sampling technique and monthly sampling of eighteen water quality variables between 06:00 to 10:00 for fifteen months (February 2015 to April 2016). Three replicates of samples were obtained for each variable from each stratum of the reservoir. Water temperature, water depth, transparency, pH and conductivity were measured in-situ using combined portable meters. Water sampling and laboratory analysis were based on standard analytical methods for examination of water and waste-water. Temporal and spatial dynamics of the reservoirs were investigated using multivariate statistical methods to obtain three seasonality regimes from the water quality with total variance in both reservoirs < 88.5%. Water quality in both reservoirs could support Nile tilapia culture (temperature between 26.730 ⁰C, dissolved oxygen > 5 mg l-1, average water depth > 3 m but < 10 m, pH was slightly acidic to slightly alkaline). Geographical information system-based spatial multi-criteria analysis results indicate that 3.85 km2 (39.05% suitability) and 2.15 km2 (68.40% suitability) of reservoir area were suitable for the development of cage aquaculture in Tono and Vea reservoirs, respectively. Estimates of carrying capacity i.e. production, physical, ecological, and social were integrated to obtain the final aquaculture CC of 719.40 m-3 and 65.55 m-3 as production volume for Tono and Vea reservoirs, respectively. Results for trophic level index (TLI) indicate that Tono reservoir has very high nutrient enriched waters (TLI: 5.23; super trophic), whiles Vea reservoir has high nutrient enriched waters (TLI: 4.32; eutrophic). Based on the trophic status, percentage allocation of aquaculture CC and other secondary data; the three AMAs in Tono reservoir and the five AMAs in Vea reservoir could produce 107.91 and 9.83 metric tonnes of cultured Nile tilapia per production cycle respectively. The study postulate that the ecosystem approach to aquaculture could be pragmatic stepwise approach that has salient potential to deal with environmental, economic and social issues associated with cage culture in Tono and Vea reservoirs. Best management practices (BMPs), physical and biosecurity measures are needed to minimise aquatic animal health risk. The use of CC based suitable zones and identification of individual AMAs are recommended as useful for decision-making by fisheries and aquaculture regulators, managers of reservoirs and other aquaculture policy-makers for sustainable cage aquaculture in the two reservoirs.
ASSESSMENT OF TONO AND VEA RESERVOIRS FOR SUSTAINABLE NILE TILAPIA (Oreochromis niloticus) CAGE AQUACULTURE DEVELOPMENT IN UPPER EAST REGION, GHANA
(KNUST, 2019-06) ETORNYO AGBEKO
The use of man-made aquatic ecosystems such as reservoirs and dugouts originally built for water supply, irrigation and fish farming is an emerging trend in most developing countries. Most reservoirs are being assessed for their potential for cage fish culture as a result of the high demand of fish. Northern Ghana has a number of reservoirs and dugouts which were originally constructed to conserve water for irrigated farming particularly the Tono and Vea reservoirs, however they seem to be under-utilized. This study was conducted to evaluate the potential of cage aquaculture on the reservoirs by assessment of the water quality, suitable zones, carrying capacity (CC) and development of aquaculture management areas (AMAs) within two major reservoirs in Upper East Region (UER) namely; Tono and Vea reservoirs. These reservoirs were monitored using linear stratified sampling technique and monthly sampling of eighteen water quality variables between 06:00 to 10:00 for fifteen months (February 2015 to April 2016). Three replicates of samples were obtained for each variable from each stratum of the reservoir. Water temperature, water depth, transparency, pH and conductivity were measured in-situ using combined portable meters. Water sampling and laboratory analysis were based on standard analytical methods for examination of water and waste-water. Temporal and spatial dynamics of the reservoirs were investigated using multivariate statistical methods to obtain three seasonality regimes from the water quality with total variance in both reservoirs < 88.5%. Water quality in both reservoirs could support Nile tilapia culture (temperature between 26.730 ⁰C, dissolved oxygen > 5 mg l-1, average water depth > 3 m but < 10 m, pH was slightly acidic to slightly alkaline). Geographical information system-based spatial multi-criteria analysis results indicate that 3.85 km2 (39.05% suitability) and 2.15 km2 (68.40% suitability) of reservoir area were suitable for the development of cage aquaculture in Tono and Vea reservoirs, respectively. Estimates of carrying capacity i.e. production, physical, ecological, and social were integrated to obtain the final aquaculture CC of 719.40 m-3 and 65.55 m-3 as production volume for Tono and Vea reservoirs, respectively. Results for trophic level index (TLI) indicate that Tono reservoir has very high nutrient enriched waters (TLI: 5.23; super trophic), whiles Vea reservoir has high nutrient enriched waters (TLI: 4.32; eutrophic). Based on the trophic status, percentage allocation of aquaculture CC and other secondary data; the three AMAs in Tono reservoir and the five AMAs in Vea reservoir could produce 107.91 and 9.83 metric tonnes of cultured Nile tilapia per production cycle respectively. The study postulate that the ecosystem approach to aquaculture could be pragmatic stepwise approach that has salient potential to deal with environmental, economic and social issues associated with cage culture in Tono and Vea reservoirs. Best management practices (BMPs), physical and biosecurity measures are needed to minimise aquatic animal health risk. The use of CC based suitable zones and identification of individual AMAs are recommended as useful for decision-making by fisheries and aquaculture regulators, managers of reservoirs and other aquaculture policy-makers for sustainable cage aquaculture in the two reservoirs.
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.
Biological nitrogen fixation in legume - cereal intercropping systems
(1998) Kaleem, Fezrat Zenabu
In West Africa legumes are important food crops grown mainly in association with maize, sorghum and millet. Although legume/cereal association is a common practice, nitrogen contribution by legumes in such cropping systems and in rotation with cereals has not been given much attention and there have been relatively few studies on the biological consequences of this association. In order to address these issues four sets of experiments were conducted for two seasons (1992/1993) at Ibadan, Zaria and Kano situated in the Forest, Guinea savanna and Sudan savanna zones respectively. The first experiment consisted of two soybean cultivars intercropped with maize; the second experiment consisted of two cowpea cultivars intercropped with maize; the third experiment, consisted of two soybean cultivars intercropped with sorghum; and the fourth experiment, consisted of three cultivars of cowpea intercropped with millet. In the first season the legumes in all the experiments were planted either as sole crops or intercropped with cereal (either on the same-row or on alternate-rows), with fertilizer nitrogen at three levels (0, 20 or 100 kg h-1). Soybeans were either uninoculated or inoculated with a mixture of Bradyrhizobium japonicum strains TAL 102, TAL 377 and TAL 379. Sole crops of the cereals were included as checks. In the second season, the fields were cropped to the respective cereals as test crops. The design used was randomized complete block with factorial treatments in three replicates. Nodulation was assessed at flowering. At physiological maturity the total dry matter and nitrogen yields were determined. Results of experiment 1 indicate that inoculation increased nodulation, grain yield, N2 fixed and %Ndfa of soybean, the response was higher in Bossier than in TGX1485-1D. Intercropping decreased nodulation, grain yield, total N uptake and N2 fixed by soybeans. However, the extent of decrease depended on the soybean cultivar. The two methods of estimating nitrogen fixation (i.e. the Total Nitrogen Difference and the Isotope Dilution), gave similar rankings of treatments in this experiment although the methods gave different estimates of N derived from nitrogen fixation. Intercropped soybean contributed more to the succeeding maize yield than sole soybean, the highest maize yield obtained (4125 kg ha-1 was from the treatment BPN1 (Same-row with 20 kg N ha-1 fertilizer). In experiment 2, cowpea cultivar 1T86D-719 produced higher nodule weights, grain yield, total N uptake, N2 fixed, and %Ndfa than Suvita-2. Intercropping with maize decreased nodulation, total dry matter, total N uptake, and N2 fixed by cowpea compared to sole crop. However, the extent of decrease was dependent on the cowpea cultivar. For example, nodule weight of IT86D-719 was decreased by 35% (same-row) and 46% (alternate-row); whilst that of Suvita-2 was reduced by 26% (same-row) and 5% (alternate-row). Grain yield of maize was increased by 58% when grown after 1T86D-7 19 and 15% after Suvita-2 compared with when grown after maize. In Experiment 3 results showed interactive effects of cultivar x inoculation, cultivar x nitrogen and cultivar x cropping system. Soybean cultivar TGX148 5-1D out yielded Bossier in all the parameters measured under all experimental conditions. Inoculation increased nodule weight of soybean cultivar Bossier by 77% and that of TGX1485-ID by 11%. Highest nodule weights, total dry matter yield, total N uptake, N2 fixed and %Ndfa by TGX1485-ID were obtained with 20 kg N ha-1 whereas those of Bossier were obtained with 100 kg N ha-1. Intercropping with TGX1485-ID on the same-row increased sorghum yield by 10 and 26% at the 0 and 20 kg N ha-1 levels respectively, but decreased the yield at 100 kg N ha-1. However, sorghum yields were reduced to 68, 71 and 78% that of sole sorghum at 0, 20, and 100 kg N ha-1 respectively, when grown with Bossier. Grain yields of sorghum increased by 14% when sorghum was grown after Bossier and 38% after TGX 1485-ID compared with when grown after sorghum. Results obtained in Experiment 4 show that cowpea cultivar IT89KD-245 out yielded Kanannado and IT89KD-2246 in almost all parameters measured. There were interactions of cultivar x nitrogen and cultivar x cropping system with regards to the parameters measured. For instance, intercropping increased the nodule weight of IT89KD-245 by 5% but decreased those of Kanannado (22%) and IT89KD-2246 (2 8%). Grain yield of millet was increased by 4% when intercropped on the same-row with IT89KD-245 but was decreased by up to 29% and 26% when intercropped with Kananriado and IT89KD-2246, respectively. IT89KD-245 fixed consistently the highest amount of N2 with an average of 47 kg N ha-1 which was 15% and 147% more than the amounts fixed by Kariannado and IT89KD-2246, respectively. The yield of millet on previous cowpea plots ranged from 1200 to 2440 kg h&’ while previous millet plots yielded 1440 kg h-1. The results of these experiments showed that the productivity of cereal and legume intercropping is dependent upon a number of factors, whose interactions should be considered in research work. Different genotypes of the same legume have been shown to have different capacities to nodulate and fix N2 under intercropping. For instance, large differences in nodulation in the field have been shown between genotypes of cowpea and soybean intercropped with maize, sorghum or millet. Given the lack of inputs commonly available to small holders in the tropics, particularly in Africa, legumes which fix N2 and grow well without the need for inoculation such as the promiscuous soybean cultivar TGX 1485-ID, are the best solution for the immediate future. Planting arrangement of legume on either same- row or on alternate-rows with cereal affected the growth and yield performance of both legume and cereal in the mixture. TGX1485-1D intercropped on same-row with sorghum showed more vigour and gave higher yields than on alternate-rows with sorghum, whereas the reverse occurred in the case of Bossier. Total N accumulation, which is a good indication of the total amount of N2 fixed, at least in soils with a poor capacity to supply combined N is probably the best criterion for selection programmes in these ecologies. More research work needs to be directed towards nitrogen and other elements partitioning in intercropping situation. Serious attempts should be made to enhance N2 fixation in grain legumes. There is the need for agronomists and plant breeders to work in close collaboration with microbiologists in the development of better legume /rhizobial combinations.
BREEDING FOR TOLERANCE TO SALT STRESS IN RICE USING A NEW TOLERANCE DONOR, MADINA KOYO
(KNUST, 2019-06) AMOAH, NANA KOFI ABAKA
Salt stress is a major constraint that reduces productivity of many rice fields across the world. Susceptibility of the crop comes within the first few weeks of establishment and later during the reproductive stage. Many studies conducted to improve the adaptability of the crop to saline soils has focused on introgressing alleles from a few donor genetic background. To broaden the genetic base of tolerant alleles, a new salt stress donor cultivar, “Madina Koyo” was used in developing a set of introgression lines with a farmer preferred indica variety, „Sahel 317‟. To identify lines that are tolerant to the stress at the two most susceptible stages, F2 derived F3 lines (F2:3) and F3:4 lines were evaluated at the early seedling and reproductive stages respectively. To better understand the regions controlling tolerance in this new donor and to validate previously reported regions, QTL mapping was undertaken using Single Nucleotide Polymorphism (SNP) analysis from Genotype by sequencing (GBS). Salt stress caused a drastic reduction of 72% in grain yield among the F2:3 progenies. Altogether, an average reduction of 63.4% was observed for all fitnessrelated traits among selected F3:4 progenies at the early seedling stage. A total of 45 progenies had better or comparable grain yield to the donor parent “Madina Koyo” and were adjudged to be tolerant at the reproductive stage. Subsequently, another 46 progenies, representing 5% of the evaluated progenies, recorded an average SES score 1-3 and were rated as tolerant to salt stress at the early seedling stage. Out of the combined 91 progenies, only one progeny, ARS1181-1-6-27, was observed to be tolerant to salt stress at both growth stages. Another four progenies (ARS1181-1-7-6, ARS1181-1-6-6, ARS1181-1-8-26 and ARS1181-1-10-1) combined tolerance at the seedling stage with better yield stability. These five promising progenies should be further evaluated with the aim of releasing as per se or be used as parents in future forward breeding efforts. A high-density genetic linkage map was constructed for the 12 rice chromosomes using 3698 SNP markers. Composite interval mapping identified 46 QTLs on 10 chromosomes (1, 2, 3, 4, 7, 8, 9, 10, 11 and 12) for SES, shoot length, shoot dry weight and root dry weight. No QTL was identified for root length. Thirty-three out of the 46 QTLs were shoot-related QTLs while five were root related. Breeders should, therefore, focus on shoot related traits when evaluating rice germplasm for salt tolerance at the seedling stage. None of the QTLs identified was mapped in the region of previously reported major effect QTL Saltol on chromosome 1, suggesting that Madina Koyo controls tolerance from a different region by a different QTL(s). Six out of the 46 (qSDW1.1, qSDW2, qSL1.1, qSL2.2, qSL2.3 and qSL2.4) were major effect QTLs with phenotypic contributions ranging from 11% - 99%. Comparison with literature suggests the novelty of these major effect QTLs. Fine mapping of these novel QTLs in a different genetic background is necessary to confirm their stability and use in breeding to enhance the level of tolerance through MAS for the pyramiding of different QTLs to one genetic background .
BREEDING FOR TOLERANCE TO SALT STRESS IN RICE USING A NEW TOLERANCE DONOR, MADINA KOYO.
(KNUST, 2019-06) AMOAH, NANA KOFI ABAKA
Salt stress is a major constraint that reduces productivity of many rice fields across the world. Susceptibility of the crop comes within the first few weeks of establishment and later during the reproductive stage. Many studies conducted to improve the adaptability of the crop to saline soils has focused on introgressing alleles from a few donor genetic background. To broaden the genetic base of tolerant alleles, a new salt stress donor cultivar, “Madina Koyo” was used in developing a set of introgression lines with a farmer preferred indica variety, „Sahel 317‟. To identify lines that are tolerant to the stress at the two most susceptible stages, F2 derived F3 lines (F2:3) and F3:4 lines were evaluated at the early seedling and reproductive stages respectively. To better understand the regions controlling tolerance in this new donor and to validate previously reported regions, QTL mapping was undertaken using Single Nucleotide Polymorphism (SNP) analysis from Genotype by sequencing (GBS). Salt stress caused a drastic reduction of 72% in grain yield among the F2:3 progenies. Altogether, an average reduction of 63.4% was observed for all fitnessrelated traits among selected F3:4 progenies at the early seedling stage. A total of 45 progenies had better or comparable grain yield to the donor parent “Madina Koyo” and were adjudged to be tolerant at the reproductive stage. Subsequently, another 46 progenies, representing 5% of the evaluated progenies, recorded an average SES score 1-3 and were rated as tolerant to salt stress at the early seedling stage. Out of the combined 91 progenies, only one progeny, ARS1181-1-6-27, was observed to be tolerant to salt stress at both growth stages. Another four progenies (ARS1181-1-7-6, ARS1181-1-6-6, ARS1181-1-8-26 and ARS1181-1-10-1) combined tolerance at the seedling stage with better yield stability. These five promising progenies should be further evaluated with the aim of releasing as per se or be used as parents in future forward breeding efforts. A high-density genetic linkage map was constructed for the 12 rice chromosomes using 3698 SNP markers. Composite interval mapping identified 46 QTLs on 10 chromosomes (1, 2, 3, 4, 7, 8, 9, 10, 11 and 12) for SES, shoot length, shoot dry weight and root dry weight. No QTL was identified for root length. Thirty-three out of the 46 QTLs were shoot-related QTLs while five were root related. Breeders should, therefore, focus on shoot related traits when evaluating rice germplasm for salt tolerance at the seedling stage. None of the QTLs identified was mapped in the region of previously reported major effect QTL Saltol on chromosome 1, suggesting that Madina Koyo controls tolerance from a different region by a different QTL(s). Six out of the 46 (qSDW1.1, qSDW2, qSL1.1, qSL2.2, qSL2.3 and qSL2.4) were major effect QTLs with phenotypic contributions ranging from 11% - 99%. Comparison with literature suggests the novelty of these major effect QTLs. Fine mapping of these novel QTLs in a different genetic background is necessary to confirm their stability and use in breeding to enhance the level of tolerance through MAS for the pyramiding of different QTLs to one genetic background
Breeding Maize (Zea Mays L.) Hybrids with Combined Tolerance to Striga Hermonthica and Low Soil Nitrogen for the Northern Savanna Zones of Ghana
(KNUST, 2019-06) Gloria Boakyewaa Adu
ABSTRACT Maize is an important staple crop widely produced and consumed in West and Central Africa (WCA). Low soil nitrogen (low-N), recurrent drought and Striga hermonthica infestation are major constraints to maize production and productivity in WCA. The specific objectives of this study were to (i) determine genetic diversity among 100 selected set of maize inbred lines using Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphism (SNP) markers (ii) classify the selected set of inbred lines into heterotic groups using the general combining ability effect of multiple traits (HGCAMT) method, SSR and SNP markers, and to compare effectiveness of the different methods in grouping the inbred lines, (iii) determine the combining ability and heterosis for grain yield and agronomic traits of the selected set of inbred lines under Striga infestation, low-N and optimal growing conditions, (iv) determine the grain yield potential and yield stability of hybrids derived from the selected inbred lines under Striga infestation, low-N and optimal growing conditions. Substantial genetic and phenotypic variability existed among the inbred lines used in this study for grain yield, Striga resistance/tolerance and low-N tolerance. Although SSR markers used in this study were highly informative, the use of large number of SNP markers made the SNP comparable with the SSR for genetic diversity analysis, and better than SSR in cluster and population structure analyses. Genetic analysis of 150 hybrids derived from the North Carolina Mating Design II revealed significant differences among the hybrids for grain yield, Striga resistance and low-N tolerance. General combining ability and SCA mean squares were significant for grain yield and most traits under optimal, Striga-infested and low-N environments and across environments, indicating that both additive and non-additive gene actions were important in the inheritance of the traits. The inheritance of grain yield under low-N and across environments were controlled largely by additive gene action, while the inheritance of grain yield under optimal and Striga-infested environments were controlled largely by non-additive gene action. Non-additive gene action largely modulated the inheritance of almost all traits measured under Striga-infested environments, except for Striga damage syndrome rating at 8 WAP. The SNP genetic distance based heterotic grouping method was identified as the most efficient in grouping the inbred lines into heterotic groups. The yield response and stability analyses of the 150 hybrids and six local checks over 10 contrasting environments indicated that 62% of the hybrids had average stability across environments, while 8% had above average stability and were adapted specifically to either Striga-infested or low-N environments. The hybrids TZdEI 215 x TZdEI 192, TZEI 378 x TZdEI 215 and TZEI 3A x TZdEI 192 were the highest yielding and most stable across environments. They are recommended for further testing and commercialization in the savanna zones of Ghana and other countries in WCA.

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