Die Ergebnisse aus den beiden Dauerfeldversuchen verdeutlichen, dass die mineralische N Düngung wie erwartet den größten Einfluss auf die Höhe der THG Emissionen hat. Die höchsten THG Minderungspotenziale zeigten sich folglich in der Reduktion der mineralischen N Düngung, insbesondere wenn die N Düngung oberhalb des standortspezifischen Ertragsoptimums liegt. Die Anpassung der Fruchtfolge kann zur Erhöhung der Bodenkohlenstoff-Vorräte beitragen und letztendlich die THG Emissionen mindern, allerdings bedarf diese These weiterer Untersuchungen. Die Ergebnisse haben weiterhin gezeigt, dass mit dem Aufbau organischer Bodensubstanz durch Stalldung erhebliche Potenziale zur THG-Minderung verbunden sind. Je nach methodischem Ansatz zur Berücksichtigung von Bodenkohlenstoff-Veränderungen ergaben sich allerdings große Unterschiede in den THG-Bilanzen und letztendlich auch in den ermittelten THG-Minderungspotenzialen. Die Entwicklung eines einheitlichen wissenschaftlichen Verfahrens zur Berücksichtigung von Bodenkohlenstoff-Veränderungen wird deshalb empfohlen. Die Ergebnisse aus der Fallstudie haben gezeigt, dass die THG Minderung in der landwirtschaftlichen Praxis eine Veränderung der Ackerflächenverhältnisse erfordert. In diesem Zusammenhang ist der Anbau emissionsintensiver Fruchtarten mit einer intensiven mineralischen N Düngung wie beispielsweise Winterraps zu reduzieren und durch den Anbau emissionsarmer Fruchtarten zu ersetzen. Im untersuchten landwirtschaftlichen Betrieb erwiesen sich Mais mit organischer N Düngung sowie der Anbau von Leguminosen als besonders emissionsarm. In der vorliegenden Arbeit konnte darüber hinaus gezeigt werden, dass ein positiver Beitrag der ackerbaulichen Bodennutzung zur THG Minderung nicht zwangsläufig mit höheren Kosten für den Landwirtschaftsbetrieb verbunden sein muss, wenn bei der betriebswirtschaftlichen Optimierung die THG Emissionen angebauter Fruchtarten berücksichtigt werden. / The aim of this study was to analyze the potential for reducing greenhouse gas (GHG) emissions in different land use systems on sandy soils in the Brandenburg region in Germany, based on two long-term field experiments at Thyrow and Groß Kreutz and an on farm case study. The calculations of the GHG balances are based on the LCA standard and the German emission report guidelines. There is currently no scientific consensus on how soil organic carbon changes are to be included in GHG balances. Therefore, different approaches to include soil organic carbon changes in GHG calculations from long-term field experiments were examined. The results of the long-term field experiments showed that mineral nitrogen fertilization had the greatest influence on GHG emissions. The reduction of mineral nitrogen fertilization consequently showed the biggest GHG reduction potential especially if nitrogen fertilization was above the local level. The adaptation of crop rotations may increase soil organic carbon content and thereby mitigate GHG emissions, but this hypothesis requires further research. An increase of soil organic carbon stocks by organic fertilization was shown for the use of farmyard manure. Although this had a high GHG reduction potential, there were large differences between the analytical approaches. This highlights the need to develop standardized scientific methods for assessing GHG emissions from cropping systems. The results of the case study showed that changing the proportions of different crop species can be used for GHG reduction. In particular, the reduction of crops with high mineral nitrogen demand, e.g. oilseed rape, and the substitution with crops having low GHG emissions is recommended. Maize, receiving high rates of organic fertilizer, as well as legumes showed low GHG emissions on the evaluated farm. Furthermore, this study elaborates the potential economic benefit for agricultural enterprises with regards to the correlation of GHG reduction and an optimized crop rotation.

Agriculture causes large parts of global Greenhouse gas emissions (GHGE), with livestock contributing the greatest share. Livestock-based foods are thus associated to higher GHGE than plant-based foods. Additionally, they are harmful to health when consumed in excess. The focus of this work lies on determining the potential to reduce agricultural GHGE when healthy diets and lower meat intakes were adopted in the EU. lt is also examined how much feed crops and pastures would become available for the production of biofuels. An emission tax and an emission trading system are also examined. To assess the complex interactions in the agricultural sector, a modified version of the European Forest and Agricultural Sector Optimization Model (EUFASOM) is used. The results show that a halved meat intake could reduce agricultural GHGE by a quarter and biofuel production could increase eightfold. The political instruments lack effectiveness though. The GHG tax has a low impact on nutrition and roughly 50% emission leakage. Emission trading has only a moderate effect on nutrition and over 100% emission leakage.:1 Introduction 2 Goal and scope definition 3 Methodology 3.1 Overview 3.2 Spatial resolution 3.3 Products under consideration 3.4 Base data 3.4.1 Base quantities 3.4.2 Base prices 3.4.3 Base areas 3.4.4 Demand elasticities 3.5 Production processes 3.5.1 Crop production 3.5.2 Pasture production 3.5.3 Plant oil production 3.5.4 Biofuel production 3.5.5 Sugar production 3.5.6 Livestock production 3.6 EUFASOM – Theoretical foundation 3.7 EUFASOM – Demand and supply functions 3.8 EUFASOM – Model description 3.8.1 Objective function 3.8.2 Identity and convexity constraints 3.8.3 Product balance 3.8.4 Land use restrictions 3.8.5 Nitrogen balance 3.8.6 Further accounting equations 3.9 Calibration 3.10 Integration of scenarios 4 Scenarios and results 4.1 Scenario 1: Technical potential of healthy diets 4.1.1 What are healthy diets? 4.1.2 Implementation of healthy diets 4.1.3 Scenario 1.1: Healthy diets with constant calorie intake 4.1.4 Scenario 1.2: Healthy diets with restricted calorie intake 4.1.5 Scenario 1.3: Healthy diets with restricted ruminant meat intake 4.1.6 Discussion on the potentials of healthy diets 4.2 Scenario 2: Greenhouse gas emission taxes 4.3 Scenario 3: Redistribution of emissions taxes as biofuel subsidy 4.4 Scenario 4: Emissions trading scheme for agriculture 4.4.1 Scenario 4.1: GHGE-cap on agricultural production 4.4.2 Scenario 4.2: Combined GHGE-cap on agricultural production and net-imports 4.4.3 Scenario 4.3: GHGE-cap on agricultural production and generation of allowances through producing biofuels 4.4.4 Scenario 4.4: GHGE-cap on agricultural production and imports and generation of allowances through producing biofuels 4.4.5 Discussion on ETS 5 Summary and conclusion References List of Figures List of Tables List of Abbreviations Annex 1 Base Solution Annex 2 Process parameters and associated information Annex 3 Lists of model variables, process parameters, equations and sets Annex 4 Demand elasticities Annex 5 Derivation of specific energy and protein demand of livestock Annex 6 Further assumptions for the livestock sectors