The use of phosphorus as a tracer in erosion/sedimentation studies

Thirteen undisturbed soil cores (0.65 and 1.10 m deep) were taken in a cultivated micro-drainage basin in the Loess Belt of central Belgium. The analysis of the phosphorus content of these soil samples (taken every 0.1 m in depth) clearly shows that there is a phosphorus (P)-enriched layer in sedimentation areas which extends well below the plough layer. The depth of this layer gives an indication of the amount of sedimentation which occurred since the use of chemical fertilisers. Erosion areas are characterized by a sharp drop in P content at the contact between the plough layer and the subsoil. The use of phosphorus as a tracer in soil erosion/sedimentation studies was therefore compared with the use of caesium-137 (137Cs) inventories which is a common technique to measure erosion/sedimentation rates over several decades. The results of this comparison indicate that the phosphorus analysis is less accurate than the 137Cs method, but the predicted patterns are similar.