Comparing two approaches of characterizing soil map unit behavior in solute transport

Soil maps are used to characterize spatial patterns of soil behaviour. A first approach is to characterize each soil map unit (SMU) by the behaviour of a pedogenetically representative profile; a second is to subsample each SMU and select from the sample a characteristic profile by its behaviour. The first approach was tested against the second. Using pedogenetically representative profiles resulted in biased estimations of functional properties related to water and solute transport. Soil profiles fitting to the definition of the SMU (impurities) corresponded to extreme values for four properties, which implies that impurities must be sampled when risk assessments must be made.