The loss of nutrients from agricultural land to water bodies is a serious concern in river basin management in many countries.
To gain information on the contributions of agricultural grassland to the eutrophication of water bodies, this study set out to
assess phosphorus (P) loss from grassland areas on poorly drained soils. A second aim was to look at the impact of grassland
management practices on nutrient concentrations in overland flow.
Edge-of-field measurements of overland flow quantity and of P and nitrogen (N) concentrations in overland flow were carried
out at three study sites with different soil P levels. The amounts of overland flow and the P concentrations in overland flow
varied considerably during events, and among sites and events. Despite this variability, there was a clear increase in P loss in
overland flow from the low to the medium and high soil P sites. The inter-site variability of the P concentrations in overland
flow greatly exceeded the variability of the amounts of overland flow from the different sites. Thus, P concentrations had a
larger impact than the volume of overland flow on the differences in P exports from the three sites. Management practices
which, at times, influenced the P and N concentrations in overland flow were grazing and N fertilisation