56 research outputs found
UrbanFoodplus â African-German Partnership to enhance resource use efficiency in urban and peri-urban agriculture for improved food security in West African cities
Food security in West Africa not only depends on productivity increases in marginal rural areas, but also on enhanced use of intensively farmed agricultural ânicheâ lands such as the urban and peri-urban spaces. They are characterised by easy market access and input availability which allows self-reinforcing processes of agricultural intensification. However, too little is known about resource use efficiencies, matter flows and negative externalities in these systems. Starting from general assessments (status quo analyses), the African-German UrbanFoodPlus (UFP) network develops and tests site-specific, farmer-tailored innovations. These directly address the above mentioned knowledge gaps in the fourWest African cities of Ouagadougou (Burkina Faso), Tamale (Ghana), Bamako (Mali), and Bamenda (Cameroon). At all locations farmers attempt to cope with increasing land pressure by cultivating along electrical power lines, on public property, and on undeveloped private land
Tolerant pearl millet (Pennisetum glaucum (L.) R. Br.) varieties to low soil P have higher transpiration efficiency and lower flowering delay than sensitive ones
Algal Photosynthesis as the Primary Driver for a Sustainable Development in Energy, Feed, and Food Production
High oil prices and global warming that accompany the use of fossil fuels are an incentive to find alternative forms of energy supply. Photosynthetic biofuel production represents one of these since for this, one uses renewable resources. Sunlight is used for the conversion of water and CO2 into biomass. Two strategies are used in parallel: plant-based production via sugar fermentation into ethanol and biodiesel production through transesterification. Both, however, exacerbate other problems, including regional nutrient balancing and the world's food supply, and suffer from the modest efficiency of photosynthesis. Maximizing the efficiency of natural and engineered photosynthesis is therefore of utmost importance. Algal photosynthesis is the system of choice for this particularly for energy applications. Complete conversion of CO2 into biomass is not necessary for this. Innovative methods of synthetic biology allow one to combine photosynthetic and fermentative metabolism via the so-called Photanol approach to form biofuel directly from Calvin cycle intermediates through use of the naturally transformable cyanobacterium Synechocystis sp. PCC 6803. Beyond providing transport energy and chemical feedstocks, photosynthesis will continue to be used for food and feed applications. Also for this application, arguments of efficiency will become more and more important as the size of the world population continues to increase. Photosynthetic cells can be used for food applications in various innovative forms, e.g., as a substitute for the fish proteins in the diet supplied to carnivorous fish or perhapsâafter acid hydrolysisâas a complex, animal-free serum for growth of mammalian cells in vitro
Climate change effects on winter chill for tree crops with chilling requirements on the Arabian Peninsula
Fruit production systems that rely on winter chill for breaking of dormancy might be vulnerable to climatic change. We investigated decreases in the number of winter chilling hours (0â7.2°C) in four mountain oases of Oman, a marginal area for the production of fruit trees with chilling requirements. Winter chill was calculated from long-term hourly temperature records. These were generated based on the correlation of hourly temperature measurements in the oases with daylength and daily minimum and maximum temperatures recorded at a nearby weather station. Winter chill was estimated for historic temperature records between 1983 and 2008, as well as for three sets of synthetic 100-year weather records, generated to represent historic conditions, and climatic changes likely to occur within the next 30 years (temperatures elevated by 1°C and 2°C). Our analysis detected a decrease in the numbers of chilling hours in high-elevation oases by an average of 1.2â9.5 h/year between 1983 and 2008, a period during which, according to the scenario analysis, winter chill was sufficient for most important species in most years in the highest oasis. In the two climate change scenarios, pomegranates, the most important tree crop, received insufficient chilling in 13% and 75% of years, respectively. While production of most traditional fruit trees is marginal today, with trees barely fulfilling their chilling requirements, such production might become impossible in the near future. Similar developments are likely to affect other fruit production regions around the world
Cross-Location Analysis of the Impact of Household Socioeconomic Status on Participation in Urban and Peri-Urban Agriculture in West Africa
This study explores the relation between household socioeconomic status (SES) and participation in urban and periurban agriculture (UPA) in three West African cities. We used a structured questionnaire to survey 700 randomly selected households: 250 in Kano, Nigeria, 250 in Bobo Dioulasso, Burkina Faso, and 200 in Sikasso, Mali. Multiple correspondence analysis was applied on household asset variables to create an index of assets which was used as a proxy for household SES. The results showed no significant differences in householdsâ rate of participation in UPA across socioeconomic groups. Participation in UPA was rather significantly (Pâ<â0.001) and positively related to household size. Interestingly, the analysis revealed that field crop cultivation and gardening were more common among households in the low and medium SES groups while those in the high SES group were more likely to keep livestock
Micromechanical Properties of Injection-Molded StarchâWood Particle Composites
The micromechanical properties of injection molded starchâwood particle composites were investigated as a function of particle content and humidity conditions.
The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness
of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence
were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density
and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starchâwood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that
the wood in the starch composites did not prevent water loss from the samples.Peer reviewe
Vertical distribution of heavy metals in wastewater-irrigated vegetable garden soils of three West African cities
Application of untreated wastewater to irrigate urban vegetable gardens is raising serious concern about possible health risks associated with the consumption of these vegetables particularly with regard to the concentrations of heavy metals (HM) in their edible portions. The soil concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn), were investigated in seven vegetable gardens from the three West African cities of Kano (Nigeria), Bobo Dioulasso (Burkina Faso) and Sikasso (Mali). Also determined were inputâoutput balances of Cd and Zn from five vegetable gardens under 30 years of wastewater irrigation in Kano. In these gardens Cd (2.3â4.8 mg kg-1) and Zn (13â285 mg kg-1) concentrations throughout the profile attained unsafe levels. The concentrations of Cu (0.8â18 mg kg-1), Cr (1.8â72 mg kg-1), Ni (0â17 mg kg-1) and Pb (0.6â46 mg kg-1) were below the safety thresholds for arable soils. Overall, concentrations of Zn, Cd, Pb and Ni were higher in Kano than in Bobo-Dioulasso and Sikasso. Inputâoutput analyses in Kano indicated that irrigation wastewater contributed annually 400â3,700 g Cd ha-1 and 7,200â22,300 g Zn ha-1, fertilizer 30â2,100 g Cd ha-1 50â17,600 g Zn ha-1, harmattan dust 0.02â0.4 g Cd ha-1 and 40â200 g Zn ha-1 while 300â500 g Cd ha-1 and 2,700â4,700 g Zn ha-1 came from rainwater inputs. Inputâoutput calculations subtracting the amounts of HM taken out in vegetable biomass and that lost to leaching from total inputs yielded an annual net positive balance of 700â4,160 g Cd ha-1 and 9,350â39,700 g Zn ha-1. If such balances remain unchanged for another 10â20 years vegetables raised in these garden fields are likely to be unsuitable for human consumptio
The explanatory power of silent comics: An assessment in the context of knowledge transfer and agricultural extension to rural communities in southwestern Madagascar
Gefördert durch den Publikationsfonds der UniversitÀt Kasse
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