Farmers' agronomic and social evaluation of productivity yield and N2-fixation in different cowpea varieties and their subsequent residual N effects on a succeeding maize crop

Cowpea-maize rotations form an important component of the farming systems of smallholder farmers in the forest/savannah transitional agro-ecological zone of Ghana. We evaluated five cowpea varieties for grain yield, N-2-fixation, biomass production, and contribution to productivity of subsequent maize grown in rotation. We further analyzed the interrelationship between these technical dimensions and the social acceptability of these cowpea varieties for farmers. Cowpea grain yield ranged between 1.1 and 1.4 t ha(-1) with no significant yield differences among the different varieties. Using the N-15 natural abundance technique, the average proportion of N-2 fixed ranged between 61% for Ayiyi and 77% for Legon prolific. This resulted in average amounts of N-2 fixed in above-ground biomass ranging between 32 and 67 kg N ha(-1), respectively. Variation in estimates due to differences in delta N-15 among reference plants were larger than differences between cowpea varieties. The amount of soil-derived N ranged from 15 to 20 kg N ha(-1). The above-ground net N contribution of the cowpea varieties to the soil (after adjusting for N export in grains) was highest for Legon Prolific (31 kg N ha(-1)) due to high N-2-fixation and high leaf biomass production. Maize grain yield after cowpea without application of mineral N fertilizer ranged between 0.4 t ha(-1) with maize after maize to 1.5 t ha(-1) with Legon Prolific. The N fertilizer equivalence values for the cowpea varieties ranged between 18 and 60 kg N ha(-1). IT810D-1010 was ranked by the farmers as the most preferred cowpea variety due to its white seed type, short-duration, ease of harvesting and good market value. Despite the high leaf biomass production and high amount of N-2 fixed by Legon Prolific, it was generally the least preferred variety due to lower market price, late maturity, least potential cash income (due to the red mottled seed type) and difficulty in harvesting. Although farmers recognized the contribution of cowpea to soil fertility and yields of subsequent maize, they did not consider this as an important criterion for varietal selection. Soil fertility improvement must be considered as an additional benefit rather than a direct selection criterion when designing more sustainable smallholder farming systems

Towards sustainable urban development: the social acceptability of high-rise buildings in a Ghanaian city

Over the years, many city managers, policy makers and academics alike have turned to high-rise buildings as pathway to sustainable urban development. However, the sustainability of such types of development in various geographical contexts, especially in sub-Saharan Africa, is a subject less explored. Amidst the promotion of high-rise development in a rapidly urbanizing metropolis in Ghana, Kumasi, the research empirically examined the social acceptability of high-rise residential facilities and the institutional capacity for their effective management. By conducting face-to-face interviews with sampled households, and critical public service providers in the metropolis, the study uncovered that, contrary to the evidence from many Asian cities, there is generally low social acceptability of high-rise developments, and a weak institutional capacity for effective service delivery. The research concludes that, whilst it is tempting to embrace high-rise buildings as sustainable development pathway, it is crucial they are pursued with much circumspection. In addition to their design being tailored to the local needs of the people for whom they are built, the promotion of high-rise development should recognize the importance of effective service delivery, and general social acceptability

Forest Nursery Operations and Knowledge of Plant Parasitic Nematodes in Four Forest Districts of the Ashanti Region of Ghana

Nursery establishment for healthy seedlings is an integral part of afforestation and reforestation projects. Plant parasitic nematodes (PPNs) are amid the destructive pathogens that greatly threaten forest nurseries. This study assesses forest nursery operations and knowledge of  PPNs of four forest districts of Ashanti region of Ghana, namely Juaso, Mankranso, Offinso, and Nkawie. Respondents comprised only forestry staff involved in managing forest nurseries. A Structured and semi-structured interview schedule was employed for data collection. Data obtained were analyzed using the Statistical Package for Social Science version 23. Descriptive statistics were used and means presented using tables and graphs. From the study, all the respondents (100%) established temporary nursery to meet seedlings demand.  Majority of the respondents (83.3%) sourced soil from abandoned refuse dump while few (16.7%) collected top soils from unfarmed sites for raising seedlings. Disease occurrence in the nursery was observed by majority (75%) of the respondents while most (66.7%) of them had no idea of the causes of the diseases observed. Greater proportion (66.7%) of the respondents moreover had no knowledge of PPNs and therefore were unaware of their damage potential. Organising seminars and workshops for nursery managers on proper operations and awareness of  PPNs to enhance their knowledge is recommended.&nbsp

Urban expansion and form changes across African cities with a global outlook: Spatiotemporal analysis of urban land densities

Africa has been experiencing rapid urbanization, yet limited studies have systematically investigated urban growth dynamics across African cities. Using 25 cities as cases, we quantified urban growth and form changes in Africa via spatiotemporal analysis of urban land densities in concentric rings over three time points (1990, 2000, and 2014). The results show that African cities have rapidly grown both in population and built-up areas, which increased by about 4% and more than 5% per annum, respectively. Urban land density (defined as the proportion of the built-up area to the buildable area) in each concentric ring decreases from the city center to the urban periphery with diverse patterns among cities. Comparatively, small cities have a lower urban land density and a more dispersed urban form than medium-sized and large cities in Africa. The international comparisons between cities with over one million population in Africa, Asia (e.g., China and India), Europe, and North America (i.e., the United States) reveal that African cities have a relatively less compact urban form. Implications of these findings for the future of African cities are further proffered

Tree tenure and its implications for sustainable land management: The case of Parkia biglobosa in the Northern Region of Ghana

Parkia biglobosa is a multipurpose species found in Savannah agroforestry parklands of West Africa. The species is important as it prevents against land degradation while providing food and other products. This study focuses on how land and tree tenure arrangements affect tree populations in three traditional areas in the Northern Region of Ghana (Dagomba, Gonja and Mamprusi) and the implications that these arrangements have for sustainable land management. Focus group discussions and key informant interviews were held in the three communities to provide information on the tenural arrangements of Parkia biglobosa. A tree census was conducted to estimate the densities of Parkia biglobosa in crop and fallow fields. The study shows that differences in tenure systems in the three traditional areas have implications for Parkia biglobosa populations and also for sustainable land management. It is concluded that traditional tenure systems along with regulation protect the trees from destruction as observed in the Dagomba and Gonja areas compared to the open access system identified in Kperiga in the Mamprusi area