Ingunn Øvsthus


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NIBIO Ullensvang, 5781 Lofthus


Use of organic fertilizers in fish pond has been common since ancient times. Applying fertilizers stimulates the growth of phytoplankton, primary producers of the fish food chain. Artificial nitrogen and phosphorus fertilizers are nowadays the main types of nutrients supply in ponds. However, the use of mineral fertilizers is not sustainable due to the use of nonrenewable resource and the impact on the environment. Moreover, the Norwegian government has defined the national ambition that organic food production and food consumption should be more than 15% by 2020. Modern societies produce large amount of organic wastes, which could be reused. Ahead of utilizing such waste as fertilizers in aquaculture, the first step is to gain knowledge about the mineralization patterns in seawater. This knowledge is important to ensure proper supply time and proper amount of nutrients from waste for optimal production with minimal negative impact on the environment This poster will present a study about nitrogen mineralization pattern from organic materials relevant as fertilizers in sustainable aquaculture.


In Norway there is an incomplete resource management of side products and residuals from the main primary sectors of agriculture, fish farming and fishery. For example is the theoretically hitherto unused energy content in animal manure estimated to approximately 2,5 TWh per year, while Norwegian fish farming annually emits about 40.000 ton nitrogen and 8400 ton phosphorous into the coastal environments. Furthermore, recycling of nutrients and energy from marine fish waste of approximately 3.2 million ton fish is still at its early stages. The incomplete resource management results in environmental, economically and social costs. Consequently, an optimisation of national nutrient and energy cycling is required to increase sustainability. The establishment of individual driven resource optimisation enterprises, e.g. local biogas reactors, are often challenging both logistically and financially, particularly at relatively remote sites. This paper presents an overall conceptual approach to optimize energy and nutrient cycling, due to a cooperatively and integrated resource management system on a regional scale in Steigen, Northern Norway.