5 resultados para default externalities
em Universitätsbibliothek Kassel, Universität Kassel, Germany
Resumo:
The organic agricultural sector of Uganda is among the most developed in Africa in terms of its professional institutional network and high growth rates of number of certified farmers and land area. Smallholder farmers are certified organic through contract production for export companies using a group certification scheme (internal control system - ICS). The ICS is a viable and well-accepted tool to certify small-scale producers in developing countries all over the world. Difficulties in certification are still stated to be among the main constraints for Uganda’s organic sector development. Therefore, this paper reports a qualitative case study comprising 34 expert interviews in two organic fresh-produce export companies in central Uganda, aiming to explore the challenges which underlie organic certification with ICS. The study shows that farmers cannot be labelled as ‘organic by default’ but deliberately engage in organic production as a marketing strategy. The small quantities purchased by the organic companies lead to a difficult marketing situation for the farmers, causing production and infiltration risks on the farm level. These risks require increased control that challenges the companies organizationally. The risks and control needs are a reason to involve farmers in ICS procedures and innovatively adapt the ICS by means of a bypass around formal perspective restrictions. The paper discusses different perspectives on risks, risk control and certification.
Resumo:
Like elsewhere also in Kabul, Afghanistan urban and peri-urban agriculture (UPA) has often been accused of being resource inefficient and unsustainable causing negatives externalities to community health and to the surroundings. These arise from the inappropriate management and use of agricultural inputs, including often pesticides and inter-city wastes containing heavy metal residues and pathogens. To address these concerns, parallel studies with the aims of quantification of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) horizontal and vertical fluxes; the assessment of heavy metal and pathogen contaminations of UPA produce, and an economic analysis of cereal, vegetable and grape production systems conducted for two years in UPA of Kabul from April 2008 to October 2009. The results of the studies from these three UPA diverse production systems can be abridged as follows: Biennial net balances in vegetable production systems were positive for N (80 kg ha-1 ), P (75 kg ha-1) and C (3,927 kg ha-1), negative for K (-205 kg ha-1), whereas in cereal production systems biennial horizontal balances were positive for P (20 kg ha-1 ) and C (4,900 kg ha-1) negative for N (-155 kg ha-1) and K (-355 kg ha-1) and in vineyards corresponding values were highly positive for N (295 kg ha-1), P (235 kg ha-1), C (3,362 kg ha-1) and slightly positive for K (5 kg ha-1). Regardless of N and C gaseous emissions, yearly leaching losses of N and P in selected vegetable gardens varied from 70 - 205 kg N ha-1 and 5 - 10 kg P ha-1. Manure and irrigation water contributed on average 12 - 79% to total Inputs of N, P, K and C, 10 - 53% to total inputs of C in the gardens and fields. The elevated levels of heavy metal and pathogen loads on fresh UPA vegetables reflected contamination from increasing traffic in the city, deposits of the past decades of war, lacking collection and treatment of raw inter-city wastes which call for solutions to protect consumer and producer health and increase reliability of UPA productions. A cost-revenue analysis of all inputs and outputs of cereal, vegetable and grapes production systems over two years showed substantial differences in net UPA household income. To confirm these results, more detailed studies are needed, but tailoring and managing the optimal application of inputs to crop needs will significantly enhance farmer’s better revenues as will as environmental and produce quality.
Resumo:
The surge in the urban population evident in most developing countries is a worldwide phenomenon, and often the result of drought, conflicts, poverty and the lack of education opportunities. In parallel with the growth of the cities is the growing need for food which leads to the burgeoning expansion of urban and peri-urban agriculture (UPA). In this context, urban agriculture (UA) contributes significantly to supplying local markets with both vegetable and animal produce. As an income generating activity, UA also contributes to the livelihoods of poor urban dwellers. In order to evaluate the nutrient status of urban soils in relation to garden management, this study assessed nutrient fluxes (inputs and outputs) in gardens on urban Gerif soils on the banks of the River Nile in Khartoum, the capital city of Sudan. To achieve this objective, a preliminary baseline survey was carried out to describe the structure of the existing garden systems. In cooperation with the author of another PhD thesis (Ms. Ishtiag Abdalla), alternative uses of cow dung in brick making kilns in urban Khartoum were assessed; and the socio-economic criteria of the brick kiln owners or agents, economical and plant nutritional value of animal dung and the gaseous emission related to brick making activities were assessed. A total of 40 household heads were interviewed using a semi-structured questionnaire to collect information on demographic, socio-economic and migratory characteristics of the household members, the gardening systems used and the problems encountered in urban gardening. Based on the results of this survey, gardens were divided into three groups: mixed vegetable-fodder gardens, mixed vegetable-subsistence livestock gardens and pure vegetable gardens. The results revealed that UA is the exclusive domain of men, 80% of them non-native to Khartoum. The harvested produce in all gardens was market oriented and represented the main source of income for 83% of the gardeners. Fast growing leafy vegetables such as Jew’s mallow (Corchorous olitorius L.), purslane (Portulaca oleracea L.) and rocket (Eruca sativa Mill.) were the dominant cultivated species. Most of the gardens (95%) were continuously cultivated throughout the year without any fallow period, unless they were flooded. Gardeners were not generally aware of the importance of crop diversity, which may help them overcome the strongly fluctuating market prices for their produce and thereby strengthen the contributions of UA to the overall productivity of the city. To measure nutrient fluxes, four gardens were selected and their nutrients inputs and outputs flows were monitored. In each garden, all plots were monitored for quantification of nutrient inputs and outputs. To determine soil chemical fertility parameters in each of the studied gardens, soil samples were taken from three selected plots at the beginning of the study in October 2007 (gardens L1, L2 and H1) and in April 2008 (garden H2) and at the end of the study period in March 2010. Additional soil sampling occurred in May 2009 to assess changes in the soil nutrient status after the River Nile flood of 2008 had receded. Samples of rain and irrigation water (river and well-water) were analyzed for nitrogen (N), phosphorus (P), potassium (K) and carbon (C) content to determine their nutrient inputs. Catchment traps were installed to quantify the sediment yield from the River Nile flood. To quantify the nutrient inputs of sediments, samples were analyzed for N, P, K and organic carbon (Corg) content, cation exchange capacity (CEC) and the particle size distribution. The total nutrient inputs were calculated by multiplying the sediment nutrient content by total sediment deposits on individual gardens. Nutrient output in the form of harvested yield was quantified at harvest of each crop. Plant samples from each field were dried, and analyzed for their N, P, K and Corg content. Cumulative leaching losses of mineral N and P were estimated in a single plot in garden L1 from December 1st 2008 to July 1st 2009 using 12 ion exchange resins cartridges. Nutrients were extracted and analyzed for nitrate (NO3--N), ammonium (NH4+-N) and phosphate PO4-3-P. Changes in soil nutrient balance were assessed as inputs minus outputs. The results showed that across gardens, soil N and P concentrations increased from 2007 to 2009, while particle size distribution remained unchanged. Sediment loads and their respective contents of N, P and Corg decreased significantly (P < 0.05) from the gardens of the downstream lowlands (L1 and L2) to the gardens of the upstream highlands (H1 and H2). No significant difference was found in K deposits. None of the gardens received organic fertilizers and the only mineral fertilizer applied was urea (46-0-0). This equaled 29, 30, 54, and 67% of total N inputs to gardens L1, L2, H1, and H2, respectively. Sediment deposits of the River Nile floods contributed on average 67, 94, 6 and 42% to the total N, P, K and C inputs in lowland gardens and 33, 86, 4 and 37% of total N, P, K and C inputs in highland gardens. Irrigation water and rainfall contributed substantially to K inputs representing 96, 92, 94 and 96% of total K influxes in garden L1, L2, H1 and H2, respectively. Following the same order, total annual DM yields in the gardens were 26, 18, 16 and 1.8 t ha-1. Annual leaching losses were estimated to be 0.02 kg NH4+-N ha-1 (SE = 0.004), 0.03 kg NO3--N ha-1 (SE = 0.002) and 0.005 kg PO4-3-P ha-1 (SE = 0.0007). Differences between nutrient inputs and outputs indicated negative nutrient balances for P and K and positive balances of N and C for all gardens. The negative balances in P and K call for adoptions of new agricultural techniques such as regular manure additions or mulching which may enhance the soil organic matter status. A quantification of fluxes not measured in our study such as N2-fixation, dry deposition and gaseous emissions of C and N would be necessary to comprehensively assess the sustainability of these intensive gardening systems. The second part of the survey dealt with the brick making kilns. A total of 50 brick kiln owners/or agents were interviewed from July to August 2009, using a semi-structured questionnaire. The data collected included general information such as age, family size, education, land ownership, number of kilns managed and/or owned, number of months that kilns were in operation, quantity of inputs (cow dung and fuel wood) used, prices of inputs and products across the production season. Information related to the share value of the land on which the kilns were built and annual income for urban farmers and annual returns from dung for the animal raisers was also collected. Using descriptive statistics, budget calculation and Gini coefficient, the results indicated that renting the land to brick making kilns yields a 5-fold higher return than the rent for agriculture. Gini coefficient showed that the kiln owners had a more equal income distribution compared to farmers. To estimate emission of greenhouse gases (GHGs) and losses of N, P, K, Corg and DM from cow dung when used in brick making, samples of cow dung (loose and compacted) were collected from different kilns and analyzed for their N, P, K and Corg content. The procedure modified by the Intergovernmental Panel on Climate Change (IPCC, 1994) was used to estimate the gaseous emissions of cow dung and fuel wood. The amount of deforested wood was estimated according to the default values for wood density given by Dixon et al. (1991) and the expansion ratio for branches and small trees given by Brown et al. (1989). The data showed the monetary value of added N and P from cow dung was lower than for mineral fertilizers. Annual consumption of compacted dung (381 t DM) as biomass fuel by far exceeded the consumption of fuel wood (36 t DM). Gaseous emissions from cow dung and fuel wood were dominated by CO2, CO and CH4. Considering that Gerif land in urban Khartoum supports a multifunctional land use system, efficient use of natural resources (forest, dung, land and water) will enhance the sustainability of the UA and brick making activities. Adoption of new kilns with higher energy efficiency will reduce the amount of biomass fuels (cow dung and wood) used the amount of GHGs emitted and the threat to the few remaining forests.
Resumo:
In Khartoum (Sudan) a particular factor shaping urban land use is the rapid expansion of red brick making (BM) for the construction of houses which occurs on the most fertile agricultural Gerif soils along the Nile banks. The objectives of this study were to assess the profitability of BM, to explore the income distribution among farmers and kiln owners, to measure the dry matter (DM), nitrogen (N), phosphorus (P), potassium (K) and organic carbon (C_org) in cow dung used for BM, and to estimate the greenhouse gas (GHG) emissions from burned biomass fuel (cow dung and fuel wood). About 49 kiln owners were interviewed in 2009 using a semi-structured questionnaire that allowed to record socio-economic and variable cost data for budget calculations, and determination of Gini coefficients. Samples of cow dung were collected directly from the kilns and analyzed for their nutrients concentrations. To estimate GHG emissions a modified approach of the Intergovernmental Panel on Climate Change (IPCC) was used. The land rental value from red brick kilns was estimated at 5-fold the rental value from agriculture and the land rent to total cost ratio was 29% for urban farms compared to 6% for BM. The Gini coefficients indicated that income distribution among kiln owners was more equal than among urban farmers. Using IPCC default values the 475, 381, and 36 t DM of loose dung, compacted dung, and fuel wood used for BM emit annually 688, 548, and 60 t of GHGs, respectively.
Resumo:
Regionale Arbeitsmärkte unterscheiden sich erheblich hinsichtlich wesentlicher Kennzahlen wie der Arbeitslosenquote, des Lohnniveaus oder der Beschäftigungsentwicklung. Wegen ihrer Persistenz sind diese Unterschiede von hoher Relevanz für die Politik. Die wirtschaftswissenschaftliche Literatur liefert bereits theoretische Modelle für die Analyse regionaler Arbeitsmärkte. In der Regel sind diese Modelle aber nicht dazu geeignet, regionale Arbeitsmarktunterschiede endogen zu erklären. Das bedeutet, dass sich die Unterschiede regionaler Arbeitsmärkte in der Regel nicht aus den Modellzusammenhängen selbst ergeben, sondern „von außen“ eingebracht werden müssen. Die empirische Literatur liefert Hinweise, dass die Unterschiede zwischen regionalen Arbeitsmärkten auf die Höhe der regionalen Arbeitsnachfrage zurückzuführen sind. Die Arbeitsnachfrage wiederum leitet sich aus den Gütermärkten ab: Es hängt von der Entwicklung der regionalen Gütermärkte ab, wie viele Arbeitskräfte benötigt werden. Daraus folgt, dass die Ursachen für Unterschiede regionaler Arbeitsmärkte in den Unterschieden zwischen den regionalen Gütermärkten zu suchen sind. Letztere werden durch die Literatur zur Neuen Ökonomischen Geographie (NÖG) untersucht. Die Literatur zur NÖG erklärt Unterschiede regionaler Gütermärkte, indem sie zentripetale und zentrifugale Kräfte gegenüberstellt. Zentripetale Kräfte sind solche, welche hin zur Agglomeration ökonomischer Aktivität wirken. Im Zentrum dieser Diskussion steht vor allem das Marktpotenzial: Unternehmen siedeln sich bevorzugt an solchen Standorten an, welche nahe an großen Märkten liegen. Erwerbspersonen wiederum bevorzugen solche Regionen, welche ihnen entsprechende Erwerbsaussichten bieten. Beides zusammen bildet einen sich selbst verstärkenden Prozess, der zur Agglomeration ökonomischer Aktivität führt. Dem stehen jedoch zentrifugale Kräfte gegenüber, welche eine gleichmäßigere Verteilung ökonomischer Aktivität bewirken. Diese entstehen beispielsweise durch immobile Produktionsfaktoren oder Ballungskosten wie etwa Umweltverschmutzung, Staus oder hohe Mietpreise. Sind die zentripetalen Kräfte hinreichend stark, so bilden sich Zentren heraus, in denen sich die ökonomische Aktivität konzentriert, während die Peripherie ausdünnt. In welchem Ausmaß dies geschieht, hängt von dem Verhältnis beider Kräfte ab. Üblicherweise konzentriert sich die Literatur zur NÖG auf Unterschiede zwischen regionalen Gütermärkten und geht von der Annahme perfekter Arbeitsmärkte ohne Arbeitslosigkeit aus. Die Entstehung und Persistenz regionaler Arbeitsmarktunterschiede kann die NÖG daher üblicherweise nicht erklären. An dieser Stelle setzt die Dissertation an. Sie erweitert die NÖG um Friktionen auf dem Arbeitsmarkt, um die Entstehung und Persistenz regionaler Arbeitsmarktunterschiede zu erklären. Sie greift dazu auf eine empirische Regelmäßigkeit zurück: Zahlreiche Studien belegen einen negativen Zusammenhang zwischen Lohn und Arbeitslosigkeit. In Regionen, in denen die Arbeitslosigkeit hoch ist, ist das Lohnniveau gering und umgekehrt. Dieser Zusammenhang wird als Lohnkurve bezeichnet. Auf regionaler Ebene lässt sich die Lohnkurve mithilfe der Effizienzlohntheorie erklären, die als theoretische Grundlage in der Dissertation Anwendung findet. Konzentriert sich nun die ökonomische Aktivität aufgrund der zentripetalen Kräfte in einer Region, so ist in diesem Zentrum die Arbeitsnachfrage höher. Damit befindet sich das Zentrum auf einer günstigen Position der Lohnkurve mit geringer Arbeitslosigkeit und hohem Lohnniveau. Umgekehrt findet sich die Peripherie auf einer ungünstigen Position mit hoher Arbeitslosigkeit und geringem Lohnniveau wieder. Allerdings kann sich die Lohnkurve in Abhängigkeit des Agglomerationsgrades verschieben. Das komplexe Zusammenspiel der endogenen Agglomeration mit den Arbeitsmarktfriktionen kann dann unterschiedliche Muster regionaler Arbeitsmarktdisparitäten hervorrufen. Die Dissertation zeigt auf, wie im Zusammenspiel der NÖG mit Effizienzlöhnen regionale Arbeitsmarktdisparitäten hervorgerufen werden. Es werden theoretische Modelle formuliert, die diese Interaktionen erklären und welche die bestehende Literatur durch spezifische Beiträge erweitern. Darüber hinaus werden die zentralen Argumente der Theorie einem empirischen Test unterworfen. Es kann gezeigt werden, dass das zentrale Argument – der positive Effekt des Marktpotentials auf die Arbeitsnachfrage – relevant ist. Außerdem werden Politikimplikationen abgeleitet und der weitere Forschungsbedarf aufgezeigt.