Discharges of nutrients can cause eutrophication
Fertilizer from farmland pollutes water in the same way as discharges of nutrients from domestic waste water, aquaculture and certain types of industry. Locally, agriculture alone can cause eutrophication in a watercourse. Local pollution problems of this type can arise wherever there is farmland.
The coastline from the Swedish border to Lindesnes is vulnerable
In addition, agriculture can contribute to eutrophication of coastal waters in certain parts of the North Sea, in combination with domestic waste water, discharges from industry and long-range pollution. In Norway, the coastline from the Swedish border to Lindesnes (the southern tip of Norway) is vulnerable to excessive nutrient loads. Inputs of phosphorus to the whole area should be reduced, and for the two areas from the Swedish border to Strømtangen lighthouse near Fredrikstad, and the inner Oslofjord, additional measures should be taken to reduce the nitrogen load.
The catchments of these areas are identified as vulnerable zones according to the EU nitrates directive. In these zones, Norway is required to establish action programmes to reduce nitrogen and phosphorus pollution from agriculture.
Pollution from runoff and leakages
The main sources of nutrient pollution from agriculture are runoff and discharges from point sources. The most important point sources of discharges are leakages from storage facilities for livestock manure and silage effluent. Leakages may be caused by poor construction, insufficient storage capacity, or accidents. Spills may also occur when facilities are emptied. Although discharges of this kind may be serious on a local scale and cause severe pollution, the largest total discharges of nutrients to water are from runoff, which may also result in long-term pollution problems.
Intensive farming can cause increased runoff of nutrients
More intensive farming can cause the runoff of nutrients to increase, partly because larger quantities of fertilizers are used and larger numbers of animals are kept on each farm.
During the 1980’s and 1990’s several legal instruments were developed to prevent further loss of nutrients caused by intensive farming. In addition, economical incentives are applied to promote development of agricultural practices that will reduce the risk of nutrient loss. The agricultural authorities give financial support to farmers to encourage environmental efforts such as altering soil management regimes, establishment of vegetation zones along water courses and grassed waterways to prevent erosion.
Regulations under the Soil- and Pollution Control Act
To limit discharges of nutrients from agriculture and the environmental damage they can cause, different sets of regulations have been laid down pursuant to the Pollution Control Act and the Soil Protection Act.
The regulations relating to manure and to silage effluent are intended to reduce point discharges from storage facilities and runoff when manure is used on agricultural land, and a regulation relating to the levelling of agricultural land are to help control runoff from areas that have been levelled.
In addition to these regulations, the Ministry of Agriculture can use other regulations and grant schemes to reduce excessive nutrient inputs. These include the regulations relating to fertilizer management and a number of grant schemes that can encourage conversion to more environmentally-friendly cultivation techniques such as:
- altering soil management regimes so that farmers avoid leaving areas with no plant cover in winter
- applying fertilizer in such a way that there is no surplus of nutrients
- maintaining strips of vegetation along the edges of fields
- constructing grassed waterways to prevent erosion
Until 1997, grants were provided for technical facilities to improve environmental conditions in agriculture, and point discharges were considerably reduced as a result.
The Ministry of Agriculture is responsible for drawing up action programmes as required by the EU nitrates directive. When these have been completed, it is expected that further measures will be taken to reduce nutrient inputs from agriculture.