Environmental ethics as a concept of practice. An investigation of the view of nature, practices and knowledge in organic farming.,The ph.d. thesis consists of three sections: conceptual considerations, an empirical investigation of the relations between the view of nature and practices among Danish organic farmers and a description of four paradigms of knowledge related to organic farming. It is shown that value assumptions and value orientations are influential for the physical-material farming practice as well as for the contents and development of agronomy. Generally spoken, the thesis exemplifies how value assumptions and orientations, the view of nature and philosophy of science are of more than theoretical interest as these aspects influence concrete problemsolving.The task of the thesis embraces many disciplines and transcends the institutionalized separation between technical, agro- and natural sciences opposed to social sciences and the humanities. In this sense the task of the thesis is interdisciplinary. A conceptual frame is created for the empirical investigation and the articulation of paradigms of knowledge. The frame is based on discussions of 1) technology as an unseparable and undividable nature-culture phenomenon, 2) recent concepts of nature, 3) different points of view within the philosophy of science about the natural sciences and nontypical kinds of scientific knowledge about nature and 4) different theories about ethics treated as different theories about the foundation of values. The conceptual frame, called environmental ethics as a concept of practice, is based on ethics as virtues. It means that values are seen as rooted in social practices without only being a social product/subjective. Views of nature, scientific knowledge as well as a concrete practice can be judged objectively in a context where goal and process are specified. The conceptual frame is a tool for understanding and describing multiplicity in value assumptions, practices and (scientific) knowledge.The investigation of the relations between the view of nature and practices among organic farmers is a qualitative study and includes methodological considerations. The main methodological inspirations come from phenomenology and anthropology. This study examines the physical-material aspects of the farmers’ practices deeper than similar sociological studies. The farmers practices include knowledge of various kinds and origins.On the level of knowledge four paradigms are articulated: the paradigm of nutrients (the conventional point of view), the paradigm of soil fertility (the traditional ecological point of view), the biodynamic point of view seen as a paradigm, and the paradigm of communication (an intermediary point of view). The paradigms are shared by farmers, agronomists in extension and advisory services and agroscientific researchers. Each paradigm is described regarding contents, analysed with respect to philosophy of science and consequences for the knowledge in action are described, for instance manuring strategies. The results of the thesis are the following: two main relations are found between the view of nature and practices among the organic farmers examined, four paradigms of knowledge are articulated, and relations between views of nature/paradigms of knowledge and the obtaining of an environmentally sustainable agriculture are documentated. Two kinds of environmentally sustainable agriculture within the organic farming can be distinguished: a non-poisonous agriculture and a soil fertility and crop quality sustaining agriculture. Consequences are pointed out for extension and advisory services, for education and research within technical-scientific and agro-scientific areas and for the relationship between concrete action and research.