Water erosion and phosphorus problems in an agricultural catchment-Need for natural research for implementation of the EU Water Framework Directive

A study of erosion and phosphorus problems was carried out in central Sweden in an area with very visible erosion and negative offsite effects on water quality. The MässingsboÃ¥n catchment is dominated by agriculture and the recipient Lake Brunnsjön suffers from eutrophication. Local demonstration areas were established and local personal contacts to motivate action and local subsidies were financed for 2 years. Measures identified and/or implemented to reduce phosphorous load on the lake were grouped into: (1) improved soil fertility and minimising of soil erosion; (2) measures at or in the stream; (3) measures in the lake itself; (4) improvements of single household wastewater treatment systems. Soil management that improved aggregate stability was demonstrated to significantly reduce soil erosion and loss of particulate-bound phosphorus. In addition, high soil fertility was generally associated with good aggregate stability. Local experiments in the stream and in the lake were less successful and more research is needed. Maximum phosphorus concentration for water loading the lake without causing excessive eutrophication was calculated to be similar to the background phosphorus concentration from arable land (0.05 mg l−1).