To distinguish erosion classes, the illuvial horizon B was separated in three parts (Bt1, Bt2, and BC) that were easily recognized in the field by the identification of the B subhorizon located below the plowed layer.
The changes are related with excavation of the illuvial horizon B due to erosion and its gradual contribution to the plowed layer.
The sequence of soil horizons in the first soil profile (lysimeter 1) was as follows: (i) a top layer (litter) ~13 cm thick (horizon A); (ii) a 37-cm-thick illuvial horizon with anthropogenie disturbances, consisting of two sub-horizons, a light layer on top of a black organic-rich one (horizon B1 and horizon B0, respectively); and (iii) the parent material with two sub-horizons, a white-coloured on top of a green-coloured sub-horizon starting at a depth of 88 cm (horizon Cw and horizon Cg, respectively).
Our soil displays optimised [K.sub.s] values that vary strongly between the layers, with the lowest value (155 cm [day.sup.-1]) for the third layer, which corresponds to the bottom sub-layer of the illuvial horizon (black organic-rich layer).
So far the minimum of Pb and Cu concentrations under the illuvial horizon B has not been quite clear.
Thus, the total carbon content in topsoil horizons up to a depth of 3-40 cm exceeds its respective concentration by 2.9-3.3 times in the 2nd transelluvial meadow landscape position and by 18.2 times in the illuvial horizon B.
An argillic horizon is an illuvial horizon
that is at least 10 percent as thick as the overlying A horizon and contains 3 to 8 percent more clay.
It merges into a strongly compacted argillic illuvial horizon
, which here reaches 180 cm depth.
The interval from 66-112 cm is also now part of the BC horizon of the surface soil and an illuvial horizon
(B'X) of the fragipan.
Between these two horizons, an illuvial horizon
is formed, called albic, generally shallow and highly lixiviated or leached (see also vol.
A diagnostic subsurface horizon, the agric horizon, is an illuvial horizon
that has formed under cultivation (essentially a plough pan).
This process consists in the translocation of claysize particles from eluvial (A, E) to illuvial horizons
(mainly Bt, and to a lesser degree, in BA or BC horizons).