P fixation, many Fe oxides, strongly structured) FR Ferralsol (dominance of kaolinite and oxides) Pronounced accumulation of organic matter in the mineral topsoil CH Chernozem (very dark and well-structured topsoil, secondary carbonates) KS Kastanozem (dark topsoil, secondary carbonates) PH Phaeozem (dark topsoil, no secondary carbonates (unless very deep), high base status) UM Umbrisol (dark topsoil, low base status) Accumulation of moderately soluble salts or non-saline substances DU Durisol (accumulation of, and cementation by, secondary silica) GY Gypsisol (accumulation of secondary gypsum) CL Calcisol (accumulation of secondary carbonates) Soils with clay-enriched subsoil RT Retisol (interfingering of coarser-textured, lighter-coloured material into a finer-textured, stronger-coloured layer) AC Acrisol (low-activity clays, exchangeable Al > exchangeable base cations) LX Lixisol (low-activity clays, exchangeable base cations ≥ exchangeable Al) AL Alisol (high-activity clays, exchangeable Al > exchangeable base cations) LV Luvisol (high-activity clays, exchangeable base cations ≥ exchangeable Al) Note: The exchangeable base cations are given in cmolc kg-1. Soils with little or no profile differentiation CM Cambisol (moderately developed) FL Fluvisol (stratified fluviatile, marine or lacustrine sediments) AR Arenosol (very sandy) RG Regosol (no significant profile development) Examples Example for naming a soil with the WRB Our example soil has the following characteristics: Field characteristics (described according to Annex 1 of the WRB Manual): A soil developed from loess shows a marked clay increase in around 60 cm depth and clay coatings in the clay-richer horizon. According to the landscape setting, we presume that high-activity clays dominate. In the field, a pH value of 6 is measured in the subsoil. The lower part of the clay-poorer topsoil is light-coloured and the upper part is darker. In the clay-richer horizon, we observe redoximorphic features; the oximorphic and the reductimorphic features sum up to 30% of the exposed area, the intensive colours found in the interiors of the aggregates. In spring, reducing conditions occur. The soil is ploughed regularly. Laboratory characteristics: The laboratory analyses confirm the high cation exchange capacity per kg clay in the clay-richer horizon and the dominance of exchangeable base cations over exchangeable Al in the subsoil. In the topsoil, we find 20% clay, 10% sand and 70% silt, in the subsoil 35% clay, 8% sand and 57% silt. Organic matter concentrations in the topsoil are intermediate. The naming of the soil consists of four steps. Question 1: Does the soil have diagnostic horizons, properties and materials? The soil has the following diagnostics: argic