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The aim of this study was to evaluate the long-term (1977–2004) effects of new agricultural practices and reduced acid rain on drainwater and groundwater chemistry for an intensely cultivated arable field with sandy soil in south-west Sweden. Trends in chemical composition of the drainwater were compared with those of atmospheric deposition and groundwater. A modified crop rotation including catch crops significantly decreased the average concentration of nitrate nitrogen (NO3-N) in drainwater from 13.0 to 7.2 mg L−l. This rotation was also found to be a very effective measure against high NO3-N concentrations in shallow groundwater (1.7 m below the soil surface). The degree of phosphorus saturation (DPS) in the subsoil, calculated to be 10% and 9% by two different laboratory methods, corresponded to an average and constant concentration of dissolved reactive phosphate (DRP) in drainwater of 0.006 mg l−l. Generally lower inputs of acid deposition to the soil were confirmed by a decreasing SO4-S trend (by 3% over 24 years) in drainwater. Changes in cropping had reduced the acid load to the soil, while drainwater alkalinity showed a slow but significant positive trend amounting to 0.4% over 24 years.

Nutrient concentrations and exports were monitored for eight years in two agriculture-dominated watersheds in the central part of the Västgöta Plain in Sweden. The hydrology and the nutrient concentrations in the streams were very similar. Concentrations (monthly flow-weighted) of dissolved phosphate-phosphorus (PO4P) varied substantially during the year (from 0.03 to 0.27 mg 1−1) whereas concentrations of particulate phosphorus (PartP) varied less (from 0.03 to 0.16 mg −1). No trends in nutrient export during the eight years were found after flow-normalization of export data. Three wet periods dominated the long-term loads of the streams. Although a few events dominated annual yields of suspended solids (SS) from drainage pipes, standard deviation of annual mean SS concentration was reasonably constant between different years. However, when further developing phosphorus load models the variation in SS concentration should probably be considered. In-stream processes may contribute nearly as much to the phosphorus export as those occurring on and in arable soils in terms of their impact on the magnitude of phosphorus export. Total nitrogen (TotN) mean concentration was 5 mg 1−1 and was similar in drainage pipes and in the streams.