What can organic agriculture contribute to sustainable development? – Long-term comparisons of farming systems in the tropics

Despite the high demand for sound data on the agronomic, ecological and economic performance of organic agriculture in developing countries, systematic comparison of organic and conventional farming systems has not so far been carried out. The Research Institute of Organic Farming (FiBL), together with its partners, is presently establishing long-term comparisons of farming systems in various agro-ecological and agro-economic contexts to study the different parameters that are essential for sustainable development. To date, three study areas have been selected: (a) a sub-humid area in Kenya where farming is subsistence-oriented; (b) a semi-arid area in India where cotton is produced for the export market; and (c) a humid area in Bolivia where perennial fruits and cacao are produced for the domestic and export markets. The key elements in these comparisons are replicated long-term field trials. These are complemented by farm surveys and short-term trials under on-farm conditions. This network of comparison of farming systems in the tropics is expected to (1) put the discussion on the benefits and drawbacks of organic agriculture on a rational footing; (2) help to identify challenges for organic agriculture that can then be addressed systematically; (3) provide physical reference points for stakeholders in agricultural research and development and thus support agricultural policy dialogue at different levels

Langzeit-Systemvergleiche in Kenia und Indien: Konventionelle und biologische Erträge aus dem ersten Umstellungsjahr

Organic agriculture is more and more perceived as a promising approach to increase food security in developing countries. However, only few attempts have been made so far to assess agronomic and economic performance of organic agriculture in these^regions in a systematic way. This article reports the first year’s results of two long-term farming systems comparison field trials in Kenya and India. In sub-humid Central Kenya, on a high potential site in Meru South District (Chuka), there were no differences between yields of conventional and organic systems for the first maize and brassica crops. In contrast, organic yields were 14 to 60% lower than conventional yields on a trial site in a medium potential zone in Maragua District (Thika). It is assumed that the organic crops in Chuka could benefit from N and P mobilisation from the soil. In Thika, where N and P were less available, the crop depended on the easily soluble nutrients applied in the conventional treatments. In the semi-arid cotton belt of^Central India, biodynamic, organic, conventional and genetically modified (GM) cotton are compared. Soya and wheat are also part of the crop rotation under study. Biodynamic and organic cotton and wheat yields were 30% lower than conventional and GM yields. Soya yields did not differ between the treatments. It is suggested that yield in organic farming systems in conversion depends on initial inherent soil fertility and crop

6. MEMS based color-VGA micro-projector system

This paper presents a complete portable laser-based projection system using twofold of one dimensional magnetic actuated MEMS linear scanning micro-mirrors. Dedicated high speed electronics was developed to drive the MEMS, detect the mirror scanning position at any time and synchronize the two mirrors and the laser pulsation. The achieved projection system head is 4.5 cm3 and is able to project colorful static images and videos (50 fps) with projection size of 50 cm diagonal at 50 cm distance with VGA (640×480 px) resolution

The relationship between the perception of distributed leadership in secondary schools and teachers' and teacher leaders' job satisfaction and organizational commitment

This study investigates the relation between distributed leadership, the cohesion of the leadership team, participative decision-making, context variables, and the organizational commitment and job satisfaction of teachers and teacher leaders. A questionnaire was administered to teachers and teacher leaders (n=1770) from 46 large secondary schools. Multiple regression analyses and path analyses revealed that the study variables explained significant variance in organizational commitment. The degree of explained variance for job satisfaction was considerably lower compared to organizational commitment. Most striking was that the cohesion of the leadership team and the amount of leadership support was strongly related to organizational commitment, and indirectly to job satisfaction. Decentralization of leadership functions was weakly related to organizational commitment and job satisfaction

River Influences on Shelf Ecosystems: Introduction and Synthesis

River Influences on Shelf Ecosystems (RISE) is the first comprehensive interdisciplinary study of the rates and dynamics governing the mixing of river and coastal waters in an eastern boundary current system, as well as the effects of the resultant plume on phytoplankton standing stocks, growth and grazing rates, and community structure. The RISE Special Volume presents results deduced from four field studies and two different numerical model applications, including an ecosystem model, on the buoyant plume originating from the Columbia River. This introductory paper provides background information on variability during RISE field efforts as well as a synthesis of results, with particular attention to the questions and hypotheses that motivated this research. RISE studies have shown that the maximum mixing of Columbia River and ocean water occurs primarily near plume liftoff inside the estuary and in the near field of the plume. Most plume nitrate originates from upwelled shelf water, and plume phytoplankton species are typically the same as those found in the adjacent coastal ocean. River-supplied nitrate can help maintain the ecosystem during periods of delayed upwelling. The plume inhibits iron limitation, but nitrate limitation is observed in aging plumes. The plume also has significant effects on rates of primary productivity and growth (higher in new plume water) and microzooplankton grazing (lower in the plume near field and north of the river mouth); macrozooplankton concentration (enhanced at plume fronts); offshelf chlorophyll export; as well as the development of a chlorophyll ?shadow zone? off northern Oregon

River influences on shelf ecosystems: Introduction and synthesis

River Influences on Shelf Ecosystems (RISE) is the first comprehensive interdisciplinary study of the rates and dynamics governing the mixing of river and coastal waters in an eastern boundary current system, as well as the effects of the resultant plume on phytoplankton standing stocks, growth and grazing rates, and community structure. The RISE Special Volume presents results deduced from four field studies and two different numerical model applications, including an ecosystem model, on the buoyant plume originating from the Columbia River. This introductory paper provides background information on variability during RISE field efforts as well as a synthesis of results, with particular attention to the questions and hypotheses that motivated this research. RISE studies have shown that the maximum mixing of Columbia River and ocean water occurs primarily near plume liftoff inside the estuary and in the near field of the plume. Most plume nitrate originates from upwelled shelf water, and plume phytoplankton species are typically the same as those found in the adjacent coastal ocean. River-supplied nitrate can help maintain the ecosystem during periods of delayed upwelling. The plume inhibits iron limitation, but nitrate limitation is observed in aging plumes. The plume also has significant effects on rates of primary productivity and growth (higher in new plume water) and microzooplankton grazing (lower in the plume near field and north of the river mouth); macrozooplankton concentration (enhanced at plume fronts); offshelf chlorophyll export; as well as the development of a chlorophyll “shadow zone” off northern Oregon.Keywords: Columbia River plume, freshwater plume, RIS

Étude de la désintégration 194Hg → 194Au

The disintegration of Hg194 has been studied by β and γ spectroscopy. The half life was found to be 700 ± 100 days. No γ nor β rays have been detected between 2 et 80 keV, the upper limit of the transition energy being 83 keV (XK). The branching ratio through a possible isomeric state of Au194 is less than 1 %.La désintégration de 194Hg a été étudiée par des méthodes de spectroscopie β et γ. On a déterminé une période de 700 ± 100 jours. Aucun rayonnement γ ou β d'énergie comprise entre 2 et 80 keV n'a été détecté, la limite supérieure de l'énergie de la transition étant de 83 keV (XK). Le rapport d'embranchement vers un éventuel niveau isomérique de 194Au est inférieure à 1 %