Gypsum treatment of fields has the potential to be a new and important way to reduce phosphorus discharges from agriculture to the Baltic Sea. For farmers, it is easy to spread gypsum, and the impact of the procedure is fast and efficient. Gypsum improves the ionic strength of cultivated fields, thus reducing erosion and phosphorus runoff to waterways. According to preliminary results, gypsum treatment can reduce particulate phosphorus discharges from cultivated fields by up to 50%, but does not require any changes in farming practices, reduce the cultivated area, or weaken crops. In efforts to reduce phosphorus discharges, gypsum treatment is more cost-efficient than any other waterway protection method currently in use, as the gypsum that is spread is effective for at least five years, and the raw material needed is created as an industrial side stream.
Large-scale testing of treating farmed fields with gypsum is currently underway within the NutriTrade and SAVE projects. In autumn 2016, gypsum was spread over more than 1,500 hectares in the Lieto and Paimio area, working in cooperation with farmers. The impact of gypsum on waterways will be monitored, and based on the results, a plan for using gypsum on the coastal areas of Southern Finland will be drawn up, as well as a proposal for including the practice in agricultural subsidy systems. The NutriTrade project is financed by the Interreg Central Baltic programme, and SAVE is part of the government’s circular economy key project, financed by the Ministry of the Environment.