Informa UK Limited
Agricultural and Biological Sciences
In climate change scenarios, the frequency of high-intensity rain events in Sweden is assumed to increase. In a plot experiment at Ultuna, Uppsala, the influence of rain intensities on phosphorus (P) transport in the uppermost 0.5 m of a clay soil was studied at 16 locations. A rain simulator, 0.5 × 0.5 m and mounted 1 m above the soil surface, was used to simulate 85–500 min rain sequences causing small (4–9 mm h) and large (22–28 mm hand one extreme at 37 mm h) steady water fluxes (intensity) in the underlying soil profile. Water percolated to a zero-tension collector tray at 0.5 m depth where drain water and its sediment load was sampled at discrete time intervals. The total P (TP) mass flux ranged, at low intensity, between 12–92 μg mmin(average 28.1 μg mmin) and, at high intensity, between 83–375 μg mmin(average 168.5 μg mmin) and 648 μg mminat the extreme intensity. The soluble reactive (inorganic) P (SRP) mass flux ranged, at low intensity, between 1–65 μg mmin(average 10.0 μg mmin) and, at high intensity, between 6–205 μg mmin(average 47.9 μg mmin) and 495 μg mminat the extreme intensity. Thus, in the intensity range 4–28 mm h, TP and SRP increased, on average, by approximately 12% (μg mmin) per unit increase in intensity (mm h). The results of this study demonstrate increased sediment and P loss/mobility for clay soil under increased precipitation intensity predicted under climate change.