College of Agriculture & Natural Resources

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    Quantifying Soil and Nutrients Losses under Different Soil Amendments and Cropping Systems on a Plinthic Vetic Lixisol in Ghana
    (May, 2018) Bigabwa, Janvier Bashagaluke
    Soil erosion coupled with soil nutrients depletion affect crop production in small-scale cropping systems of sub-Saharan Africa (SSA). Reducing both threats, based on sustainable practices is crucial to enhancing crop productivity in the region. The current study was designed to help address the twin problems based on the following objectives: (i) developing and validating a new numerical method for surface runoff assessment; (ii) determining the effect of crop and soil management practices on soil loss; (iii) analyzing soil nutrients loss due to soil erosion under different amendments and cropping systems; (iv) assessing the effect of soil amendments and cropping systems on soil properties; (v) assessing the effect of soil amendments on crop productivity. In achieving these objectives, a field experiment was carried out on runoff plots under different cropping systems (commonly practiced in Ghana) treated with soil amendments. The study was a two-factor experiment in split-plot arranged in a randomized complete block design for three consecutive cropping seasons (2016 major, 2016 minor and 2017 major seasons). The cropping systems (sole maize, maize intercropped with soybean, sole soybean and cowpea) constituted the main plots whereas the subplots comprised soil amendments (inorganic fertilizers (NPK), inorganic fertilizers combined with biochar (NPK+BC), sole biochar (BC) and control). For the model development and soil erosion characterisation, a total of 33 erosive rainfall events were observed. Different statistical parameters viz. p-values, R², RMSE, NSE and RSR were used to assess the quality of the model developed. Parameters on the effects of the soil and crop management practices were analyzed in ANOVA and regression models. P value < 0.001 and R² ranging from 0.88 to 0.94 showed good accuracy of the model prediction. The dispersion between the predicted and observed values was low with RMSE varying from 1.68 to 2.66 mm. Moreover, the low variability between parameters was confirmed with the low values of RSR which ranged from 0.38 to 0.46 (with 0.00 ≤ RSR ≤ 0.50 for good prediction). During the observation periods, NSE values ranged from 0.79 to 0.86 (≥0.75 being the threshold for excellent prediction). The sensitivity analysis showed that the model under high runoff generation (simulation including bare plots), was poorly adapted. Results for crop yield and soil properties showed positive impacts of the different interventions. Soil loss characteristics based on amount of soil loss, soil depth reduction and runoff coefficient were significant (P < 0.05). Among the different treatments, sole cowpea and inorganic fertilizers application were most effective in reducing soil erosion. Also, biochar, due to its multipurpose effect on soil properties, had positive effects on soil erosion reduction compared to the control. Cumulative nutrients loss, enrichment ratios and monetary values of soil nutrients loss varied significantly under the amendments and cropping systems. Soil nutrients loss was more pronounced on the bare and the control plots than on the treated plots due to less soil erosion from the latter. All the nutrients had enrichment ratios (ER) greater than unity showing off-site nutrients deposition due to soil erosion; and this was more pronounced during the minor season than in the major seasons. The soil particles had ER greater than unity, except for the sand with values ranging from 0.77 to 0.88 and from 0.65-0.70 in the major and minor seasons, respectively. The economic effect of soil erosion based on the monetary values of soil nutrients loss was high for the control plots for each cropping system followed by the sole biochar (BC) treatment. Monetary loss under NPK and NPK+BC treatments was lowest due to their positive impacts on soil erosion reduction. The physical soil properties (bulk density and volumetric moisture content) were improved by the different practices and best values were observed under sole cowpea and sole biochar with respect to the cropping systems and soil amendments. Soil acidity increased slightly over time except under biochar treatments where a slight decline was observed. The legume-based cropping systems as well as the inorganic fertilizers applications improved soil organic carbon, total nitrogen, available phosphorus and exchangeable potassium contents slightly than the other treatments. For all the three crops evaluated (maize, cowpea and soybean), the productivity (grain and biomass yields) was better under the inorganic based treatments followed by sole biochar. Land equivalent ratio (LER) was greater than 1 under all the amendments under the maize-based systems. This emphasized the positive effect of the intercrop compared to the sole systems. With respect to cost effectiveness, VCR was greater than 2 for only sole NPK treatments under all the cropping systems and also for sole biochar treatment during the third season (2017 major). However, for NPK+BC, VCR > 2 was observed under the intercropped system throughout the study period. Indeed, sustainable nutrients management systems reduced soil loss and enhanced crop productivity and are recommended for small-scale farming activities in SSA.
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    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.
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    Standardisation of organic materials as amendment for soil and soilless media in urban horticultural production systems
    (AUGUST, 2015) Abubakari, Abdul-Halim
    A survey was carried out in Tamale and Kumasi among horticultural practitioners from March 2012 to June 2012 and subsequently, experiments were carried out from June 2012 to June 2015 to select and standardise organic materials as media for urban horticulture. Following the survey, i) single species sawdust (SS), ii) mixed species sawdust (MS) and ii) Rice husk (RH) were each co-composted with poultry manure in 2:1, 3:1 and 4:1 volumetric ratios of feedstock to poultry manure. This resulted in nine compost-types (formulations) being 2SS, 3SS, 4SS, 2MS, 3MS, 4MS, 2RH, 3RH and 4RH. Experiments were set-up in greenhouse and in the field to determine the rate of application of compost and biochar as amendment in soil and soilless media for vegetables and ornamentals. Treatments included compost-type:topsoil and compost-type:biochar mixes in soil experiments as well as compost-type:biochar mixes as soilless media. Competely Randomised Design was used for greenhouse experiments and Randomised Complete Block Design for the field experiment. The 2SS compost matured earliest (8 weeks) with Carbon: Nitrogen ratio (C:N) of 15 and highest nitrogen level of 2.46 %. The 1-part 2RH compost + 3 parts topsoil as well as 1 part of 2SS compost + 3 parts topsoil were the best for vegetables. The 2 parts of 2MS + 3 parts topsoil was the best for ornamentals. Sawdust compost (at 10 t/ha) + sawdust biochar (at 5 t/ha) was the best compost biochar mix for field production of vegetables. The 1 part of 2RH compost + 2 parts rice husk was the best media for greenhouse zinnia production. The 2SS compost + SS biochar was best media for greenhouse production of vegetables. The present study has clearly demonstrated that common agro-industrial by-products which are currently causing environmental challenges to urban authorities can be developed into nutrient rich media suitable for horticultural production systems and greening of the urban landscape.
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    Sustainability of Crop Residues and Manure Management in Smallholder Cereal-Legume-Livestock Systems in the Savannas of West Africa
    (September, 2011 ) Opoku, Andrews
    The integration of crops and livestock is an effective means of harnessing and recycling nutrients in manure and crop residues to improve crop yields. However, the competing demands for crop residues within the farm present a tradeoff between increasing crop yields and sustaining livestock productivity. The effectiveness of manure as fertiliser on the other hand is constrained by poor handling and storage techniques. This thesis addresses the challenges associated with crop residues and manure management in five studies: i) assessment of nutrient balances, ii) quantification of tradeoffs, iii) appraisal of the sustainability of crop residue uses, iv) evaluation of manure management options and v) quantification of added benefits from integrated use of mineral fertiliser and manure. The NUTMON framework was used to assess the N and P balances in cereal-legume-livestock farms at Cheyohi, Ghana (Ferric Luvisols), Sarauniya, Nigeria (Regosols) and Garin Labo, Niger (Eutric Gleysols). Nitrogen balances ranged from -7 to -22 kg ha-1 with the application of the recommended N rate and -34 to -82 kg ha-1 in the absence of fertiliser use. The application of the recommended rate of P led to the P accumulation in the order of 3 to 7 kg ha-1. However, without the application of fertiliser, P depleted at rate of 2 to 7 kg ha-1 annually. The tradeoffs for allocating crop residues between the crop and livestock units of the farm were evaluated by incorporating 0, 25, 50, 75, and 100 % of haulm and stover yield of the farm into the soil and feeding the remaining amount to small ruminants. The tradeoffs estimates favoured the incorporation of 75 % haulm and 25 % stover at Cheyohi, 25 % haulm and 75 % stover at Sarauniya, and 0 % haulm and 0 % stover at Garin Labo. An agricultural sustainability index was used to appraise the sustainability of the five management scenarios. The use of 75 % of haulm and 25 % of stover as soil amendment was found to be the most sustainable option in Farm 1 at Cheyohi. Other sustainable options were, the total removal of crop residues in Farm 1 at Sarauniya and Garin Labo, and the use of 75 % of haulm and 25% of stover as soil amendment in Farm 2 at Sarauniya. The effects of oil cakes and manure storage methods on nutrient losses during composting were evaluated at Nyankpala, Zaria and Maradi. The storage of manure in heaps or pits and fortification with oil cake had no effect on N and P losses during composting at all locations. The use of plastic sheets to cover heaps or line pits significantly reduced N losses from 29 – 67 % to 5 – 30 % and P losses from 25 – 37 % to 2 – 20 % at Nyankpala and Zaria but had no effect on nutrient losses at Maradi. The added benefits and economic returns from the combined application of mineral fertiliser and manure were evaluated at Nyankpala, Sarauniya and Maradi. Added benefits in grain yield ranged from -68 to 470 kg ha-1 at Nyankpala and -514 to 684 kg ha-1 at Sarauniya. No added benefits were found at Maradi. The most cost effective application rates were 2.5 t ha-1 of manure complemented with either 25 % of the fertiliser recommendation at Nyankpala or 50 % of the fertiliser recommendation at Sarauniya.
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    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