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• Shortly outline the paradigm change in agricultural research from traditional objectives (former indicators for progress) to modern requirements towards agriculture (current indicators for progress). Traditional indicators for progress: -Number of people fed by each farmer-Proportion of disposable income spent on food-Yield per hectare Modern (complementary) indicators for progress: -Environmental impacts-Resource use-Social impacts-Food quality Due to increasing food demand, increasing competition for land use (food, feed, fiber, fuel), climate change with unpredictable implications and great regional differences there has been a paradigm change in agricultural research.
• What are the key objectives of Organic Farming? Underline your statement by examples. Organic Agriculture is a production system that sustains the health of soils, ecosystems and people. It relies on ecological processes, biodiversity and cycles adapted to local conditions, rather than the use of inputs with adverse effects. Organic Agriculture combines tradition, innovation and science to benefit the shared environment and promote fair relationships and a good quality of life for all involved. -Maintain the long-term fertility of the soil -Closed systems and draw upon local resources -Minimize environmental pollution from agricultural activities -Produce food of high nutritional and process quality in sufficient amounts and affordable       prices -Give livestock conditions of life that conform their physiological needs and humanitarian   principles -Provide a reasonable income to farmers -Use of appropriate technologies based on an understanding of biological systems -Develop local markets with short transport chains -Preserve wildlife and agricultural biodiversity -Design of the agricultural landscape in a sustainable and aesthetically pleasant way -Prohibition of: mineral nitrogen fertilizers, soluble P and K-fertilizers. Herbicides, other   synthetic pesticides, growth hormones, seeds from GMO crops
• List different use options for growing legumes in the tropics! -Grain legumes as cash crop -Grain legumes as green manure -Fodder legumes as animal feed -Fodder legumes as green manure (Both either in pure stands or in mixture with grasses) -Introduction into pastures (Weiden)
• Shortly outline the key elements for soil fertility management in tropical organic agriculture. Soil fertility is the capacity of soil to ensure long-term crop productivity. It consists of a range of chemical physical and biological properties all contributing to sustainable crop yields. In general: Crop rotation, soil tillage, irrigation, manure, humus, soil particle size, pH,… On farm elements: Farm yard manure (fresh or composted)Harvest residues (Ernterückstände)Green manure Off farm elements: Organic household wastes (composted, e.g. vermicompost)Collected biomass (e.g. Tithonia leaves)Industrial organic wastes (rice or coffee husks (Schalen))Essential: amount and quality
• Please list factors that limit the use of green manure legumes in the tropics! -Know-how -Availability of seeds -Presence of suitable bacterial strains for infection -Rotational limitations -Climate factors: temperature, light
• Which factors determine the performance of symbiotic BNF and which factors limit its productivity in the tropics? -Presence of bacteria -Species by strain compatibility -Survival of bacteria -Climatic factors: temperature, light -Soil factors: nutrient availability (N,P,K, micronutrients esp. Mo), moisture, pH -Crop management: Defoliation (Entlaubung), competition, pest and pathogen control
• List and shortly describe approaches how to enhance biodiversity in agro-forestry systems. -AF is a tool of diversification, tools of diversification: -Rotation over time -Crop diversity within a farm -Species mixtures – intercropping, mixed cropping, agroforestry -Variety mixtures – 2 or more varieties in the same field -Composite crop populations -(Wildlife/ habitat diversity) By providing habitat for species that can tolerate a certain level of disturbance By helping to preserve germplasm of sensitive species By helping to reduce the rates of conversion of natural habitat and alleviate resource use pressure By providing connectivity through corridors created between habitat remnants and the conservation of area-sensitive floral and faunal species By helping to conserve biological diversity through providing other ecosystem services such as erosion control and water recharge, thus preventing habitat degradation and loss 5xC: Competition, Complementation, Cooperation, Capacity, Compensation
• Shortly describe ecological effects and economic benefits from agro-forestry systems. With increasing plant species richness, total productivity increases (non-linearly) Agroforestry: Mixture of Agriculture and forest : 1ha -> Agriculture and Forest separated 1.4 ha -> because of Land Equivalent Ratio (LER) -> on average LERs in AG Systems are > 1 AF can potentially… Control soil erosion Maintain soil organic matter (and hence soil fertility) Improve and sustain soil physical conditions Add substantial amounts of nitrogen to the system through nitrogen-fixing trees Capture mineral nutrients from deeper soil layers and recycle to the topsoil Form a more or less ‘closed’ ecological system Reduce soil acidity (through leaf litter) Reclaim degraded soils Improve soil biological activity and nitrogen mineralization through tree shade Enhance mycorrhizal associations through tree-crop mixtures Economic benefits: Creation of new employment opportunities Diversification of local products and economies Less reliance on fossil fuels Landscape design with view to aesthetic aspects and recreational opportunities Preservation of culture and tradition
• Which factors mainly limit the implementation of agro-forestry systems in Europe? Higher requirements for Yields, Quality etc. Mechanization in Fertilization, Harvest, Irrigation etc.
• List and shortly discuss the advantages and disadvantages of shade trees in organic coffee plantations! Shade trees can have multiple ecological benefits, but also exert competition on the crop and may reduce yields Yield reduction of coffee when shaded by trees is stronger under high input conditions Positive: Reducing extremes in high (low altitudes) and low (high altitudes) and low (high altitudes) air and soil temperatures Breaking force of wind and heavy rainfall Controlling erosion on steep slopes Suppressing weeds Producing annually 5-15 t/ha (dry weight) organic matter from litter and pruning Recycling of nutrients otherwise not available to the coffee and reducing nutrient leaching Preventing over-bearing and shoot dieback as a result of reduced light intensity Providing additional revenue from shade trees (timber, firewood and fruits) Support for secondary vine crops like black pepper and vanilla Potentially reducing incidence of diseases (e.g. leaf rust) and pests (e.g. white stem borer) Improving cup quality, particularly in ecologically sub-optimal coffee zones (high temperatures) Negative: Progressively lower yields with increasing shade intensity, due to a reduction in flowering nodes, inflorescences per node and flowers per inflorescence Competition for water between shade and coffee trees in seasonally dry regions Damage of the coffee trees by falling branches from the shade trees and occasional tree felling Additional labour costs for regularly pruning of over-head trees to avoid excessive shading Potential increase of some diseases (e.g. South American leaf spot) and pests (e.g. coffee berry borer)
• Alternatively: Describe the site requirements for cotton / coffee / tea. What are the main challenges in organic production? Specify your answers. Cotton: Arid climate Light: no shading Optimum temperature for development: 26-28 °C Soil pH: 5.5-7.5 Deep, well-drained and ventilated soil Main challenges: Conventional cotton production highly depends on extensive use of pesticides Coffee: Growing in the shade of several tree species/ summer rain area, diversified agro-ecosystems Arabica: higher altitudes, Robusta: lower altitudes Well drained and aerated soils, rich in SOM, pH<7 Optimal: soils with volcanic origin Shallow root system adapted to shallow soils Optimal temperature for Arabica 18-24°C Frost susceptible, temperature lower 10°C growth retardation Robusta tolerates higher temperatures; higher resilience against pests Optimal precipitation range: 1500 mm -1900 mm per year Homogenous rainfall distribution optimal Acceptable reaction on drought periods < 3 months Adapted to half-shade conditions Half shade plant Leaf temperature > 34°C assimilation stops Photosynthesis rate of shaded shrubs better than in full sunlight Monocultures are not useful in OA: Extensified systems: with nearly closed nutrient cycles (indigenous farmers and smallholders) Intensified systems: including nutrient purchase (organic manure) especially medium and bigger-sized farms Tea: Mean annual temperature: 18 - 20 °C (no frost) Annual precipitation: min 1600 mm Relative air humidity: 70 – 90 % Deep, friable, well drained, from sandy loam to heavy clay Rich in nutrients Acid pH 5 – 6
• Organic paddy rice production: Which nitrogen sources are basically available? Give a brief evaluation of the potential of the different sources. Azolla water fern symbiosis Anabaena azollae Cyanobacteria Green manure Organic amendments (FYM, compost, rice husk and straw)
• Please shortly explain problems related to the use of pesticides in developing countries! General problems: Disturbance of natural balance Resistance of target organisms Environmental pollution Hazards of pesticide to non target organisms Health hazards to humans Problems in developing countries: Disturbance of natural balance Inadequate regulations, legislations Lack of technical regulatory facilities (generation of toxicological data) Lack of technical personnel (monitoring systems for residues) Irresponsible distribution of in part illegal products Illiteracy, poverty or missing sanitation of users may lead to abuse and health hazards Inappropriate use (wrong indications and dosage) Negative health effects resulting from long term exposure (plantation workers) Missing consumer awareness and protection
• Please describe the crop protection concept in organic farming based on different intensity levels! 1st phase: Cultural practices compatible with natural processes, such as crop rotation, soil management, non-transgenic host plant resistance, farm/field location 2nd phase: Vegetation management to enhance natural enemy impact and exert direct effects on pest populations 3rd phase: Inundate and inoculate releases of biological control agents 4th phase: Approved insecticides of biological and mineral origin and use of mating disruption
• List cultural practices that can be used for pest control in tropical agriculture! Use of cleaned seeds Pre sowing irrigation Crop rotation Trap crop intercropping Mixed cropping Use of tolerant/resistant varieties Manipulation in sowing dates Water management Destruction of volunteer plants Management of alternate hosts plants
• Which categories of bio-pesticides are suitable for organic farming? Give examples! Botanicals (various forms of liquid plant extracts or powders) e.g. Azadirachtin extracted from Neem tree (Insecticide), Beeswax (Pruning agent), Plant oils like mint/pine/caraway oil (Insecticide, fungicide and sprout inhibitor) Inorganic agents (soaps, rock powders, etc.) often combined with bioagents e.g. Copper (Fungicide), Ferric phosphate (Molluscicide) Micro-organisms (mainly bacteria and fungi) e.g. Spinosad (Insecticide, Substances produced by micro-organisms)
• Shortly outline key problems to the development and use of bio-pesticides! Insufficient efficacy Insufficient reproducibility under different environmental conditions Active agents often unknown Standardization not possible Problems with application technique No general eco- and human toxicological harmlessness High production costs
• What are from your point of view the key challenges for future world agriculture? What role do you see for Organic Agriculture? Increase of the world population and change of consuming patterns are expected to increase food demand To satisfy the demand while seeking for sustainable production systems Increase the amount of cropland Close the yield gaps
• Please shortly explain the key environmental problems resulting from global agricultural activities in tropical regions! - Desertification - Salination - Destruction of rain forest - Monocultures

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