Sustainable agriculture: how to make it work? : a modeling approach to support management of a mixed ecological farm

Keywords: sustainable agriculture; organic farming; whole farm management; decision support; farming systems research; designing; modeling; beta-gamma integrationThe objective of the research described in this thesis was to develop a model that helps farmers to design a sustainable farm system. If sustainability must go beyond the level of vague statements, it must be implemented in operational farm management. Sustainable development was considered as an active design process by the farmer that should focus on creating and maintaining adaptive capacities in order to tune the farm system to an ever-changing environment. Because sustainability involves social, ecological and economic aspects, the farmer must be enabled to integrate soft and hard parameters in decision-making. From literature research in the fields of management science and sociology, a three-phase methodology was defined: (i) negotiate with the environment, (ii) solve problems in a heuristic way and (iii) implement solutions in operational control. This methodology enables the farmer to make his visions, intentions and values explicit. It was argued that the current scientific concept of agricultural production, production ecology, is not suitable for designing sustainable farm systems. A new concept was defined: ecological production, which takes the social and ecological environment as a starting point, while production is tuned to it. This requires a design-oriented approach in which the farmer is enabled to improve his skills. Management should focus on preventive and recycling management, which requires that the primary processes must be considered as a logistic chain of product flows. Based on the three-phase-methodology and the concept of ecological production, a model was developed. The model consists of several components of which the so-called Product Flow Model is the most important one. It represents the production process as a chain or network of product flows between production units, internal and external resources. Other components help to define sustainability goals and connect them with the Product Flow Model, followed by a translation into operational management, resulting in the so-called Sustainability Management Handbook. The model was tested and illustrated by two case studies on potato production and nutrient management. The model and methodology was evaluated by expert validation. The general conclusion was that the approach is suitable for implementing sustainability in operational farm management and that, potentially, it helps to improve farmer's skills, but this was not sufficiently justified