Challenges to Organic Farming and Sustainable Land Use in the Tropics and Subtropics

The central aim of Organic Farming is to maintain and improve soil fertility as a means of supporting animal health by species-adapted animal keeping and feeding. These two aims have developed from the basic desire of many human beings to live in harmony with nature, ultimately emanating from a wish to sustain their own health.In industrialised countries of temperate humid climate, diseases of modern civilisation have been developing at an alarming rate. One of the main reasons is excessive and incorrect nutrition, resulting from alienation in preparing and making our own foodstuffs. In this respect, food procurement today looks at qualitative aspects, i.e. at changes in nutritional habits, especially at a reduction of excessive meat consumption, but also at taking precautionary action to ensure that foodstuffs are free of pathogenic agents and harmful substances. In many tropical and subtropical regions, man is not supplied with sufficient amounts of food. In this context food procurement means protection against hunger and help in the daily fight for survival. This means that the main focus is on quantitative aspects of food production. However, the risks of intensive farming also have a completely different magnitude in tropical and subtropical regions due to themuch more frequent occurrence of acute poisoning after the improper use of pesticides (Castillo, X., 2000).Organic Farming tries to meet the demands of man in temperate humid as well as in tropical and subtropical regions and to provide something of a unifying element. The tension between these different demands and the resulting exciting discussion is a specific feature of our faculty ”Ecological Agricultural Sciences” in Witzenhausen, with its strong roots in both Sustainable Tropical and Subtropical Agriculture and in Organic Farming.In the view of a soil biologist, who tends to consider the aspects of soil fertility, the basic principles of Organic Farming mainly rely on the efficient and careful use of natural resources in all climatic regions (Paoletti, M.C. et al., 1993; Lavelle, P. et al.,1999). Under temperate humid climatic conditions, Organic Farming is especially devoted to protection against environmental pollution. Under tropical and subtropicalclimates, the possibilities of human intervention are enormously restricted due to the environmental conditions, e.g. nutrient deficiency of many soils or the drought of the climate, even if sufficient mineral fertilizers were available (Prasad, R. and Power, J.F., 1997). A characteristic feature of Organic Farming is the attempt to integrate problems into a systematic approach, to resist the temptation of simple solutions in mono-causal reason-effect-relationships, e.g. in finding a soil biological reference number that gives a fertilizer recommendation with a constant value. The euphoria in the use of molecular biological methods in the area of gene technology generates the suspicion that scientists search with complex methods for apparently simple solutions. This leads to the expectation that crop yields can be miraculously increased, for example, by introducing and switching on a gene. Problems are dealt with by taking immediate action, leading to fast and furious campaigns. Tackling problems in a systematic way, often called a holistic approach, entails the inherent risk that a specific topic will be dealt with very superficially.It is a major problem that the transfer of knowledge from temperate humid to tropical/ subtropical regions is impossible or seriously restricted. The use of easily-soluble mineral P-fertilizers is n ot really useful in P-fixing soils regularly occurring in large areas of tropical and subtropical regions (Castillo, X., 2000). Through promotion of soil microorganisms, e.g. by suitable soil organic matter management, P is much better held in biological cycles. However, knowledge about the control mechanisms of biological processes in tropical and subtropical soil is very sparse, especially considering the observation that the composition of the microbial decomposer community differs enormously in tropical and subtropical soils from those in humid temperate regions (Rees, R.M. et al., 1999).Not only is available knowledge regarding the large diversity of the tropical and subtropical regions restricted, but the realization of the farmers themselves is also hampered by quite different problems to those experienced in industrialised temperate humid regions.The cultural and political conditions, for instance with regard to property rights and the level of education, mean that the transfer of scientific knowledge can often only take place within very close limits (Bolanos, M.F., 2000). While the profession of a farmer requires an academic education in some countries of the European Union, land-using persons in tropical and subtropical regions are often very poorly educated, often lacking the most basic reading and writing skills. This problem is becoming increasingly serious with the increasing disappearance of rural traditions.A special advantage of Organic Farming is the fact that it always takes the social and political environment of human beings into consideration and not only the production of foodstuffs. Even more important for the development of sustainable agriculture in the tropics and the subtropics is the future oriented character of Organic Farming. In setting itself current limits in the means of production, its outlook into the future is unlimited

Spectral density of the Dirac operator in two-flavour QCD

We compute the spectral density of the (Hermitean) Dirac operator in Quantum Chromodynamics with two light degenerate quarks near the origin. We use CLS/ALPHA lattices generated with two flavours of O(a)-improved Wilson fermions corresponding to pseudoscalar meson masses down to 190 MeV, and with spacings in the range 0.05-0.08 fm. Thanks to the coverage of parameter space, we can extrapolate our data to the chiral and continuum limits with confidence. The results show that the spectral density at the origin is non-zero because the low modes of the Dirac operator do condense as expected in the Banks-Casher mechanism. Within errors, the spectral density turns out to be a constant function up to eigenvalues of approximately 80 MeV. Its value agrees with the one extracted from the Gell-Mann-Oakes-Renner relation

Chiral symmetry breaking in QCD Lite

A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of (Mpi^2 Fpi^2)/2 with respect to the quark mass m in the chiral limit, where Mpi and Fpi are the mass and the decay constant of the Nambu-Goldstone bosons. We compute the spectral density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar meson mass and decay constant by numerical simulations of lattice QCD with two light degenerate Wilson quarks. We use CLS lattices at three values of the lattice spacing in the range 0.05-0.08 fm, and for several quark masses corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this coverage of parameters space, we can extrapolate all quantities to the chiral and continuum limits with confidence. The results show that the low quark modes do condense in the continuum as expected by the Banks-Casher mechanism, and the rate of condensation agrees with the Gell-Mann-Oakes-Renner (GMOR) relation. For the renormalisation-group-invariant ratios we obtain [\Sigma^RGI]^(1/3)/F =2.77(2)(4) and Lambda^MSbar/F = 3.6(2), which correspond to [\Sigma^\MSbar(2 GeV)]^(1/3) =263(3)(4) MeV and F=85.8(7)(20) MeV if FK is used to set the scale by supplementing the theory with a quenched strange quark.Comment: 4 pages, 3 figures, 1 tabl

DsD_s physics from fine lattices

We present a preliminary analysis of the charm quark mass and the mass and decay constant $f_{D_s}$ of the $D_s$ meson obtained from dynamical simulations of $N_f = 2$ Wilson QCD on the large and fine lattices simulated by the CLS effort.Comment: 6 pages, 2 figures; talk presented at Lattice 2008, XXVI International Symposium on Lattice Field Theory, July 14-19, 2008, Williamsburg, Virginia, US

Ist eine europäische Wirtschaftsregierung eine sinnvolle Option?

Rainer Brüderle, Bundesminister für Wirtschaft und Technologie, sieht für eine weitergehende Zentralisierung der Wirtschaftspolitik keinen Grund. Die für die jeweilige Situation eines Mitgliedstaats bestmögliche Ausgestaltung von Strukturreformen gelinge am ehesten in nationaler Verantwortung und entsprechend den nationalen Gegebenheiten. Georg Fahrenschon, Bayerischer Staatsminister der Finanzen, warnt vor einer europäischen Wirtschaftsregierung einschließlich nivellierender Steuerungsfunktion. Ihre Befürworter seien bislang den Beweis schuldig geblieben, dass der Ansatz Europas Wettbewerbsfähigkeit stärken und nicht schwächen wird. Auch Carsten Hefeker, Universität Siegen, spricht sich gegen eine gemeinsame Wirtschaftsregierung aus. Man müsse sich die Frage stellen, wo Externalitäten bestehen und Mechanismen zum Eindämmen dieser Externalitäten nötig seien. Und man müsse sich auf die konsequente Durchsetzung von beschlossenen Regeln einigen. Rainer Schweickert, Universität Siegen, argumentiert in seinem Beitrag, dass man Regierungsversagen nicht mit mehr Kompetenzen für die Regierungen bekämpfen sollte. Eine europäische Wirtschaftsregierung könne nicht dazu beitragen, die gegenwärtige Krise besser zu bewältigen bzw. zukünftige Krisen zu vermeiden. Es gelte, die Spielregeln zu verbessern und damit sowohl Markt- als auch Regierungsversagen zu verhindern. Für Konrad Lammers, Europa-Kolleg Hamburg, stellt eine europäische Wirtschaftsregierung keine brauchbare Alternative dar. Aus seiner Sicht fehlen in der Währungsunion Anreiz- und Sanktionsmechanismen, die die wirtschaftspolitischen Akteure zu einem verantwortungsvollen Verhalten sowohl auf der nationalen wie auch auf der europäischen Ebene anhalten

Neopterin inhibits ATP-induced calcium release in alveolar epithelial cells in vitro.

BACKGROUND: Serum neopterin concentrations rise during activation of the cellular immune system. It is suggested that neopterin interacts with cellular redox mechanisms. This induces oxidative stress, which inhibits intracellular Ca2+ transients in various cell types. In type II alveolar epithelial cells, Ca2+ increase is considered involved in the exocytosis of surfactants. This exocytosis is disturbed during inflammation. AIMS: To clarify whether neopterin affects adenosine triphosphate (ATP)-induced Ca2+ transients in an alveolar epithelial cell line (L2). METHODS: Ca2+ transients were detected as fura-2 fluorescence by an image analysis system. RESULTS: Cells were exposed for 100 sec to ATP (1 microM, repeated four times). The first application of ATP induced an increase of the fluorescence ratio by approximately 100%, while the following stimulations resulted in smaller transients. In a second set of experiments, L2 cells were exposed to ATP or ATP + neopterin (100 nM), alternately. Simultaneous application of neopterin inhibited Ca2+ transients almost completely. CONCLUSIONS: Inhibition of Ca2+ transients by neopterin may lead to suppressed exocytosis of surfactant proteins in alveolar epithelial cells. This might contribute to the deterioration of pulmonary functions in the course of inflammatory processes

Mikrobiologische Indikatoren der Bodenfruchtbarkeit in einem Zweikulturen-Nutzungssystem

In dieser Untersuchung wurden die Auswirkungen die C- und N-Mineralisation und die Rolle der mikrobiellen Biomasse als möglicher Stickstoffpuffer bzw. Zwischenspeicher in einem Zweikulturennutzungssystem erfasst. Die Ergebnisse der Untersuchung beziehen sich auf den pflanzenbaulichen Versuch von Graß und Scheffer 2002 auf der Hessischen Staatsdomäne Frankenhausen. Dabei sollte die Auswirkung von Bodenbearbeitungsmaßnahmen und Düngerapplikationen unterschiedlicher Intensität durch die monatlichen Erhebungen zur Erfassung des mikrobiell gebundenen Kohlen- und Stickstoffes, der C- und N-Mineralisationsleistung abgeschätzt werden. Da der Versuch zum Zeitpunkt der Tagungsanmeldung noch nicht abgeschlossen war, sind in dieser Kurzfassung nur die unvollständigen Datensätze enthalten

Evaluation of a theory of instructional sequences for physics instruction

Background of the study is the theory of basis models of teaching and learning, a comprehensive set of teaching models which includes for example learning through discovery and problem solving. The combined use of different teaching models has not been fully investigated and it is frequently not clear under what circumstances a particular teaching model is used by teachers. In contrast, the theory of basis models of teaching and learning gives guidelines for choosing a particular teaching model and provides instructional sequences for each teaching model. Aim of the study is to investigate the implementation of the theory applied to physics instruction and to show if possible effects for the students may be attributed to the use of the theory. Therefore, a theory-oriented education program for 18 physics teachers was developed and implemented in the 2005/06 school-year. Main features of the intervention consisted of coaching physics lessons and video analysis according to the theory. The study follows a pre-treatment-post design with non-equivalent control group. Findings of repeated-measures ANOVAs show large effects for teachers’ subjective beliefs, large effects for classroom actions and small to medium effects for student outcomes such as perceived instructional quality and student emotions. The teachers/classes that applied the theory especially well according to video analysis showed the larger effects. Results of this study showed that differentiating between different teaching aims improves physics instruction. Effects can be followed through to student outcomes. The education program effect was clearer for classroom actions and students’ outcomes than for teachers’ beliefs

Organische Substanz in ökologisch bewirtschafteten Böden,Quantität, Qualität und ihr Einfluss auf Getreideerträge

In an on-farm investigation a total of 39 fields of 9 organic managed farms (main crop winter cereals) were sampled in the years 2005 and 2006. Several soil variables were evaluated as well as crop yield, weather data and the field history. Results of statistical analyses (mean, range, standard deviation, correlation and multiple linear regression) are presented. Comparable to physical and chemical variables certain fields were also characterised by soil biological variables. Main factors of cereal N-yield were pre crop, crop rotation, soil type and soil organic matter content (SOM). Soil biological variables had only a low influence. Nitrogen availability was affected by physical and biological soil factors, the weather and management measures as straw fertilization and pre crop. Negative correlations between SOM and yield or N-availability were probably caused by the connection of SOM and environmental factors