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Andersson, Helena (2008) Jordbrukets påverkan på Östersjön. Other thesis, SLU.

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The Baltic Sea, due to its special conditions, is a unique and vulnerable marine environment. There are many pressures that have an impact on the sea and one of the major problems is the extensive flow of nutrients from land. The most visible effect of the supply of nutrients is the annual algal blooms. One of the main sources of nitrogen and phosphorus supply is agriculture. Nutrient losses from arable land have been increasing as agricultural production has intensified. At the end of the twentieth century an increased awareness of these problems led to the formation of organizations such as HELCOM and Baltic 21. While these international organizations work in different ways to restore the state of the marine environment and decrease the supply of nutrients, they all use indicators to illustrate the situation and track improvements. Indicators are an approach used to characterize a complex reality. This approach has been used for example to point out the main factors in agriculture that have an influence on the nutrient balance of the Baltic Sea. While an indicator does not represent a complete explanation, it can sometimes shed light on some aspects of a problem and hopefully even on possible solutions. A number of important agricultural factors that may have an impact on the Baltic Sea are presented more closely and studied in this analysis. The results suggest that for some of the indicators there is a correlation with nutrient losses. The connection between nutrient balances and losses is clear – an increased surplus in nutrient balances leads to an increase in nutrient leaching to the sea. The highest nitrogen losses come from Denmark and Germany (57 and 40 kg N/ha agricultural land), the two countries with the greatest surpluses. Finland, the country with the highest phosphorus losses (1.1 kg P/ha agricultural land), also has a significant phosphorus surplus. There is a clear correlation between animal density and nitrogen balance which indicates that there may be measures to be taken in order to decrease nitrogen losses from agriculture. The problem with using animal density as an indicator for the agricultural influence on the Baltic Sea is that measures can be taken which decrease nutrient losses without actually decreasing the amount of animals. The positive changes that arise from these measures may therefore not be possible to see in this indicator. The study also showed a correlation between production of meat, cereals and milk and nutrient balances of both nitrogen and phosphorus which indicates that nutrient losses increase as the production of each of these increases. However, a high use of mineral fertilizers did not show any correlation with high nutrient losses from agricultural land. In addition, while forage plants and fallow land are known to have low nutrient losses compared to areas with cereals, the study did not show on any link between these factors and nutrient losses. Finally, the study shows that on the whole, correlations between nitrogen balances and different agricultural factors generally are more pronounced than those for phosphorus.

Item Type: Thesis (Other)
Keywords: Jordbruk, Östersjön, indikator, belastning, kväve, fosfor
Subject (faculty): Faculty of Veterinary Medicine and Animal Science > Dept. of Soil and Environment
Divisions: SLU > Faculty of Natural Resources and Agricultural Sciences
Depositing User: Anne Olsson
Date Deposited: 06 Oct 2008
Last Modified: 18 Aug 2015 10:08
URI: http://ex-epsilon.slu.se/id/eprint/2867

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