SMEAR-Agri Viikki station is built at Viikki Research Farm (in Helsinki, Finland) on fine textured mineral soil. The station offers an international top-level platform for research activities, and it provides continuous H2O, CO2, CH4 and N2O flux measurements by eddy covariance and chambers, automated soil measurements (temperature, moisture, electrical conductivity, redox, water table depth), vegetation, and atmospheric measurements of reactive gas concentrations, aerosols and aerosol precursors. All the measurements are conducted year-round over multiple years to decades.