World Reference Base for Soil Resources Soils, Section 2

426© 2007 ecomed publishers (Verlagsgruppe Hüthig Jehle Rehm GmbH), D-86899 Landsberg and Tokyo • Mumbai • Seoul • Melbourne • Paris

J Soils Sediments 77777 (6) 426 – 430 (2007)

Soils, Section 2: Global change and environmental risk assessmentWorld Reference Base for Soil Resources (Subject Editor: Andreas Lehmann)

WRB-Excursion on Technosols and Stagnosols through Germany in August 2007Andreas Lehmann1* and Peter Schad2

1Institute of Soil Science and Land Evaluation (310), Hohenheim University, 70593 Stuttgart, Germany2Lehrstuhl für Bodenkunde, Technische Universität München, Germany

* Corresponding author (as@uni-hohenheim.de)

DOI: http://dx.doi.org/10.1065/jss2007.11.260

Please cite this paper as: Lehmann A, Schad P: WRB-Excursion on Technosols and Stagnosols through Germanyin August 2007. J Soils Sediments 7 (6) 426–430

Abstract. About 40 anthropogenic soils and soils altered by stag-nant water were presented during an excursion through Ger-many. The discussion during this tour aimed mainly at the defi-nitions of the WRB (World Reference Base for Soil Resources)soil groups Technosols and Stagnosols.

Keywords: Anthropogenic urban soils; hydromorphic soils;stagnosols; technosols; World Reference Base for Soil Resources(WRB)

Introduction

The soil groups Technosols and Stagnosols which were re-cently introduced into the second edition of the WRB (WRB,2006) have been studied in August 2007 during an eightdays lasting tour through Germany. The excursion startedin the Ruhr area in North-West-Germany, on-going in thearea of Halle and South of Halle in Central Germany, fi-nally forwarding to South-West Germany. Proposals for theimprovement of the WRB classification were formulatedduring an in-door discussion at Hohenheim University atthe last day. Twenty-eight participants from twelve coun-tries shared the excursion which traced back to a proposi-tion by A. Lehmann (Hohenheim) during the IUSS (Interna-tional Union of Soil Sciences) congress in Philadelphia in2006. Hence, A. Lehmann took over the general organiza-tion of the tour. The WRB working group of the IUSS (O.Spaargaren, Wageningen und P. Schad, Weihenstephan) wasinvited by the AK Bodensystematik (Working group on soilsystematic of the German Soil Science Society, chaired by G.Milbert, Krefeld, Fig. 1).

1 Soils presented in the Ruhr Area (R1–R14)

The first part of the excursion took place at the startingpoint of the industrialization in Germany, in the Ruhr area.There, in the 19th century, the industrialization (productionand manufacturing of iron and steel, primary chemical in-dustry, heavy machine engineering and power generation)developed parallel to hard coal mining. Since the 1950ies,the economic performance of the primary and secondarysector decreased in the Ruhr area in favor of activities of the

tertiary sector. Today about 5.3 million people are living inan area of around 4,500 square kilometers. Actually, theRuhr area has lost 7% of its residents since 1960. Also, theunemployment rate is still about 15%.

The substrates of the presented soils were according to theland use history of the Ruhr area: hard coal sludge and min-ing spoil, gravel, rubble, tar and slags as well as ashes andsewage sludge. These anthropogenic substrates were oftenmixed or overlaid with local loess. Dust, from differentsources such as industry and traffic as well as from weather-ing of constructions represent a widespread addition to thesoils of the Ruhr area.

The first soil (R1, Mollic Urbic Technosol) showed stagnantwater but no hydromorphy. Nevertheless, the subsoil showedstrong reaction with α, α, dipyridyl indicating the presenceof Fe++. The stagnation of water in this soil consisting of

Fig. 1: Participants of the WRB-Excursion on Technosols and Stagnosols2007 discussing a Technosol from slags in the Ruhr Area

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multiple layers containing rubble ashes and loess loam wascaused by subsoil compaction. The compaction leads in somesoil horizons to a bulk density exceeding 1.8 g·cm–3. Thiswas discussed as a wide-spread phenomenon in anthropo-genic urban soils. Additionally, the importance of urban soilsfor a tolerable urban climate was discussed.

Taxonomic questions arising during the discussion in thefield are summarized in the subsequent chapter. For expla-nations of the prefix qualifiers and for the full WRB classifi-cation with suffix qualifiers, analytical data and pictures fromthe soil profiles see an update of the excursion guide com-prising 200 pages. This is scheduled for December 2007 andwill be available via http://www.uni-hohenheim.de/soil/TechnoStagno2007GuideUpdate.pdf.

The subsequently presented profile of an anthropogenic ur-ban soil (R2, Technic Regosol) in a park area showed someother general characteristics of urban soils: high contents oforganic matter and plant available phosphorous as well ashigh amounts of coarse material and a high pH in the sub-soil. The substrate in which the soil developed was depos-ited in a former fire water pond; dredged during World WarII and filled afterwards with a mixture of fine rubble, plas-ter, ashes, organic waste and loess loam. This material wascovered with fertile soil material. The discussion at the opensoil pit addressed the problem of distinguishing betweentechnogenic and organogenic carbon.

The next soil pit (R3, Mollic Endostagnic Technosol) fo-cused on the problem of mixing toxic and nontoxic sub-strates while depositing. The lead content in differently col-ored compartments of the profile, for example, differed by1000%. In consequence, problems for the evaluation of suchsoils on the base of average contents occur. Therefore, tech-niques for separation of different materials should be intro-duced in large scale operating.

We discussed soils under sealing and soils altered by reduc-tive gases at a profile (R4, Spolic Ekranic Technosol) openedby roadwork. Thus, we had access to a ditch dug under astreet where a gas pipeline showed a leakage. A strong blu-ish color indicated the reduction by gas. This phenomenonis widespread along old gas pipelines. Additionally, the rel-evance of sealed soils for the water and nutrient supply ofstreet trees was discussed there.

A short walk on a 100-year-old heap of hard coal spoil cov-ered by an overaged Robinia forest allowed us an insightinto a less compacted soil (R5, Folic Spolic Cambisol, bulkdensity: 0.4 g·cm–3 in 10 cm depth, 1.3 g·cm–3 in 70 cm depth)with about 10 cm in situ accumulated organic matter. Theoriginal pH of 7 decreased to pH 4 as a consequence ofoxidation of sulfuric acid.

The following two soils originating from rubble (R6, UrbicTechnosol, 25 years old) and hard coal spoil (R7, SpolicTechnosol, 8 years old) were very skeletic and compacted.A 7 cm thick topsoil with some organic matter has devel-oped in the R 6-soil from rubble (pH: 8 to 9), whereas notopsoil development was visible in the 8-year-old R7-soilfrom spoil (pH 10).

The last profile shown on the first day (R8, Spolic Technosol)developed mainly from dolomite stones, brought there in1885 for the construction of track beds. The stone contentranges from 70 to 90% within the first meter of depth. Ad-mixed to the dolomite, slags and ashes are present in the up-per part (above 40 cm) and hard coal mining spoil in the lowerpart. Dust was incorporated in the upper 15 cm. The weath-ered slags and ashes caused a brownish color. Further down,mottling caused by stagnant water was developed in the hardcoal mining spoil. This soil was high in heavy metals.

The fist site of the second day was an excellent example todemonstrate formation of carbonate and silica by weather-ing of slags (R9, Endogleyic Spolic Technosol). The surfaceof the soil was remarkable, because it consists of cementedcalcium carbonate. This, because calcium oxide from blastfurnace slags (e.g., slags from iron extraction contain approx.40% CaO) gets dissolved by and reacts with water. There-fore, CaO changes to calcium hydroxide which bonds car-bon dioxide from the air to form carbonates. These reac-tions are similar to the reactions of the technical carbonatecycle. There, the same processes of slaking calcium oxide(quick lime) and setting (of slaked lime or lime mortar) tocalcium carbonate (lime) occur.

Besides much of CaO, higher concentrations of MgO, K2Oand Na2O are present in most blast furnace slags due to thehigh temperatures in the furnace during metal processing.These chemical compounds cause high pH levels from 8 to12 when dissolved in water. Since silica in slags is oftenpoorly crystallized and becomes soluble at pH 9, it is pre-sumably dissolved and translocated in young soils from blastfurnace slag. Then, Zeolithes are preferably formed duringperiods of water saturation, when concentrations of sodiumand potassium are increasing in the water (Sauer andBurghardt, 2006). Therefore, a jackhammer was needed toopen this profile. The next stop enables a view on liquiddeposited slags which hardened to a massive, several meters,towering formation.

The last four soils shown in the Ruhr area (annual precipi-tation: 820 to 930 mm (R 14), mean annual temperature:9.6°C) were influenced by stagnant water. All these soilswere formed from unconsolidated sedimentary rock. AnAbeluvisol (R11) and two Planosols (R12, R13) were devel-oped from marine clay covered with fluvial sand and gravel.The Planosols showed an abrupt textural change caused bysedimentation. Another Albeluvisol (R14) was developedfrom loess. The four profiles showed prominent and clearredoximorphic mottles, reducing conditions and many iron-manganese segregations as a result of a temporary reduc-tion by stagnant water.

2 Soils presented in Central Germany (H1–H8)

In the evening of the second day, the excursion moved toHalle in Central Germany by train. There, the tour contin-ued the following morning. After a sound introduction intothe area of Saxony-Anhalt, the excursion focused on an-thropogenic soils, most of them from ashes.

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The first soil profile (H1, Endogleyic Spolic Technosol) de-veloped from rubble, tar and oil residues was situated at alake shore site with spontaneously grown Phragmites. In thegranular structured topsoil, more than 50 Lumbricidae persquare meter had been detected. The site was marked by anintense odor of phenols and by bluish-blackish soil colors.The concentration of polycyclic aromatic hydrocarbonsranged around 40 μg·g–1. The concentration of petroleum-derived carbons ranged from 40 μg·g–1 (topsoil) to near50,000 μg·g–1 (subsoil). Lead (297 μg·g–1) was the most criti-cal heavy metal in the topsoil. The soil, which was about 85years old, showed a negative Eh (–100 mV) in the subsoil(ground water level: 50 cm below surface).

After a short discussion, the participants of the tour went tothe former opencast lignite mine Geiseltal, southeast of Halle.There, the surface of the soils had a deflation pavement ofsand and gravel. The whole site was affected by some sheeterosion and by heavy rill erosion. Only sparse vegetationwas developed, even from the grass that was sown for green-ing. In this area, the substrate for soil development changedat a small scale. One profile from lignite and another fromsilty loamy mine spoil (with two pits) were presented. Thesoil from lignite (H2.1, Haplic Regosol, bulk density: 0.4 to0.5 g·cm–3) showed rooting only along clefts, and aggrega-tion was low in topsoil and subsoil. Phosphorous and po-tassium were not restrictive for plant growth. The pH in thetopsoil was about half a pH unit lower than in the subsoilthat had a pH of 5.8.

The two neighboring pits of soil from mine spoil (H2.2.1,H2.2.2, both Spolic Technosols, bulk density: 1.0 to1.5 g·cm–3, pH: around 5.5, Corg: around 10%, C/N: around1:100) showed granular to angular blocky aggregates andvery little rooting. Nevertheless, the nutrient supply of thesoils of the two pits differed strongly. One pit with a well-developed Ah horizon and a high content of plant availablephosphorous and potassium showed a high amount(> 800 kg·ha–1) of microbiological biomass, while the soilof the other pit showed contradicting properties.

The subsequent soil profile lies to the southeast of Halle (atOsendorfer See) at a hillside of lignite ash with skeletal loamysand over skeletal sandy loam (H3, Vitric Spolic Technosol)and 25 years of soil formation. The soil is still calcareousthroughout. It has a well aggregated topsoil and is rooted tonearly 1 m depth. The available water capacity ranges from45% in the topsoil (bulk density: 0.65 g·cm–3) to not lessthan 25 % below 35 cm (bulk density: 0.51 g·cm–3). Thecontent of organic carbon in the topsoil (0–5 cm) was 4.7%(C/N: 57) and the color of the Ah was dark brown (0–5 cm:10YR 6/1, 5–35 cm: 10YR 6/6). Carbonate and gypsum werewashed out to some extent and precipitated at 70 cm depth.

The following soil profile (Halle-Bruckdorf, H4, SpolicTechnosol) indicated clearly by its skewed boundaries thatits parent material was deposited by tilting (loams and sandsfrom mine spoil). A platy structure was visible throughout

the soil. The roots access a depth of more than 1 m. Enrich-ment of Corg took place in the topsoil (0 to 5 cm, Corg: 8%,C/N: 67) where granular and platy structure was expressed.The pH decreased from 4.2 to 3.2 from the surface to 140cm depth (CECpot from 27 to 17 cmolc·kg–1, accordingly).

The site in Halle-Trotha, visited next, was a former clay pitwhich was then used as a pond (size: 7 ha, capacity: 1.6million m3) to pump in an ash-water suspension. The asheswere the output of power plants working with differentqualities of brown coals and various burning techniquessince 1924. Two highly stratified soils from the flushedmaterial were shown (H5.1, H5.2, Gypsic Vitric FluvicSpolic Technosols, Zikeli et al. 2005). These soils, one coarsegrained, one finer grained, experienced 17 years of soil de-velopment before sampling. H5.1 was from sand from lig-nite ash (CECpot: around 20 cmolc·kg–1, pH-H2O: around8.5, bulk density: 0.6 to 0.9 g·cm–3), H5.2from silt loamfrom lignite ash (CECpot: around 40 to 70 cmolc·kg–1, pH-H2O: 8, bulk density: around 0.4 g·cm–3). Their topsoilswere structureless (H 5.1: Corg: 7%, C/N: 70, bulk density:0.65 g·cm–3; H 5.2: Corg: 32%, C/N: 81, bulk density:0.42 g·cm–3). In both soils gypsum was formed from cal-cium hydroxide and sulfur.

The next presented soil was 15 years old and developed froma calcium hydroxide and calcium oxide suspension from sodaproduction (H6, Fluvic Spolic Technosol). The light yellow-ish topsoil showed a granular structure (Corg: 2.5%, C/N:14), the whitish subsoil was still coherent showing shrink-age clefts. The soil was characterized by decreasing carbon-ate concentrations (mainly calcite, 55 to 44%) and bulkdensities (0.36 to 0.25 g·cm–3) depth-wise, as well as by anelectrical conductivity and a pH which increased with depth(from 1.5 to more than 10 mS·cm–1, pH-H20: from 8 to 9).Results from isotope analyses indicated that calcite wasformed initially near the surface of the alkaline slurry bybinding CO2 from the atmosphere. Much calcite was formedin an extremely short time span. The soil also showed asurprisingly fast accumulation of organic matter.

The last anthropogenic soil shown in the area of Halle(Weißandt-Gölzau) had developed from lignite ash andrubble with a lot of fine- and coarse-sized lignite particles(H7, Vitric Spolic Technosol). Due to the technique of tilt-ing, the ash-rubble boundary slopes through the profile. TheCorg content in the topsoil was 8% (C/N: 26, bulk density:0.59 g·cm–3).

The part of the tour in central Germany was closed by thepresentation of a natural soil (H8, Stagnic Cutanic Albe-luvisol) influenced by stagnant water. There, Gustaf AdolfKrauss (1888–1968) developed the concept of 'gleiartigeBöden' which leads to the soil type Pseudogley in the Ger-man soil classification. The soil in the Wermsdorfer Forest(annual precipitation: 650 mm, mean annual temperature:8.4°C) developed from periglacially reworked loess loamand showed prominent mottling. The stagnation of waterwas caused by clay illuviation below 50 cm depth.

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3 Soils presented in southwest Germany (S1–S11)

In the afternoon of the fourth tour day, the group moved toStuttgart and arrived there at late night. The following dayand the morning of the last tour day was dedicated to natu-ral soils formed by stagnant water which were located onthe Swabian Alb, in Upper Swabia and the 'Obere Gäue'(area between the Black Forest and the Swabian Alb). Theprincipal differences between these soils are shown inTable 1.

Most of the presented hydromorphic soils developed under7°C mean annual temperature, only the soils in Stuttgartexperienced 8.5°C annual temperature. The texture of S 1(Stagnic Cutanic Albeluvisol from Pleistocene solifluctiondeposit consisting from loess and clay (latter from limestoneweathering)) ranged from SiL above 63 cm depth to SiCLbelow 63 cm. The soil showed no indication of clay illuvia-tion, but many blackish-brownish concretions are presentin the subsoil. S 2 (Stagnic Albeluvisol from penultimate gla-cial till, throughout SiL) was marked by a formation, alter-ation and translocation of clay in a moderate degree. Coarsemottles and large oxide concretions could be observed inthe pit. Only few clay skins could be found in the deep sub-soil of S 3 (Haplic Stagnosol from penultimate glacial tillfrom reworked sandy Molasse (Tertiary)), a soil with a sandcontent increasing with depth (from 27 to 38%). Slicken-sides were found in S 4 (Vertic Stagnosol from Opalinuston(Middle Jurassic clay) below the E horizon. There, the hy-dromorphic mottling was prominent. S 5 (Alic Stagnosolfrom Loess above Lettenkeuper (Upper Triassic clay), SiLabove SiCL) showed medium-sized mottles that were dis-tinct in the E horizon and prominent in the horizon below.The two hydromorphic soils in Stuttgart (S 6 from peri-glacially reworked loess above Lower Jurassic clay and S 8from periglacially reworked loess, Stagnic Cutanic Albelu-visols) showed clear hints of clay illuviation.

Then, anthropogenic soils were the topic of the afternoonof the last tour day. First a dump site was visited, wherewaste with higher portions of organic material was coveredwith 45 cm of loess in the 1980ies (S 8, Garbic Technosol).Reductive gases were emitted there. After about 20 yearsmainly of CO2-emissions, the soil now predominantly emitsCH4. These gases caused reductive features below 35 cm ina loess cover, whereas further upwards oxidative hues aredetermining the soil color. This reddish coloring was causedby iron, mobilized below 35 cm and transported upwardsby ascending water.

The subsequent soil was about 55 years old and consisted ofrubble backdating to World War II and a substrate fromLate Jurassic (S 9, Urbic Technosol). This material was filledinto a ravine to a maximum depth of 7 m. Large parts of thesoil were occupied by the coarse material that was calcare-ous throughout. Soil development was nearly restricted tothe topsoil, where organic matter accumulation and aggre-gation took place. Some signs of initial iron oxidation werefound in the subsoil.

The following, quite contrasting profile was also calcareousthroughout (S 10, Urbic Technosol). It was about 80 yearsold and consisted mainly of refuses from a slaughter houseand from a cooking plant. This material was covered withloamy soil material, poor in artefacts and a moderate bulkdensity. The sandy subsoil with ashes and a lot of artefactslike bottles, broken dishes and bones had a bulk density ofonly 0.7 g·cm–3. The color of the subsoil from 25 to 80 cmdepth has changed to a brighter brown which signifies anintense iron oxidation. The content of carbonates was rela-tively low in these brighter brownish parts.

The tour closed with a soil bearing much historical infor-mation (S 11, Technic Cambisol). The deeper subsoil con-sisted from ashes and horse dung brought there in the 19th

century, when the garbage collection was managed by horse

No. of profile

Pleistocene frost cracks

Absence of stagnant water

(frequency)

Approximate soil age [years]

Lithological discontinuity (li. disc.) or

clay illuviation (clay ill.)

Intensity of stagnation, according to 1. wet period

2. hydromorphy

Reason for water stagnation

S 1 + less than once per year

> 20,000 li. disc. ++++

clayey texture

S 2 + never dry > 20,000 li. disc. +++++

dense subsoil

S 3 + every year 12,000 li. disc. ++

dense subsoil

S 4 – once per three years 2,000 li. disc. +++++

clayey texture

S 5 (+) every year 12,000 li. disc. +++

sandstone in 1 m depth

S 6 + every year 12,000 clay ill., li. disc.

+(+)++

clayey subsoil and claystone in 2 m depth

S 7 + every year 12,000 clay ill. +++

clayey subsoil

Table 1: Outline to the hydromorphic soils presented in southwest Germany

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and cart. This sandy material became subsoil material whenit was moved in the 1960ies to model a park area. Abovethis material, a more clayey substrate from Late Jurassicwas deposited. According to agricultural soil evaluation, thedescribed soil is best suited for corn growing. Highly criticalconcentrations of heavy metals were restricted to a depthbelow 45 cm.

Altogether, most of the wide range of anthropogenic soils,their properties and functionality (Lehmann 2006) could bepresented during the tour. Numerous questions arousedabout the soil development in technogenic soils. Further clari-fication is necessary, if similar looking phenomena of soildevelopment in natural and anhtropogenic soils are alike ornot. In respect to hydromorphic soils, the determination ofthe soil functionality by stagnant water became obvious. Thefact, that a number of these soils were classified as Albelu-visols, which may not have stagnant water, was turned outas problematic. These points became input for the follow-ing day, dedicated to constructive discussion for completionsand changes of the WRB-framework.

4 Soil Classification

A major objective of the tour was to test the definitions ofthe Reference Soil Groups of Technosols and Stagnosols.

Technosols comprise three kinds of soils with a strong influ-ence of human technical activities: Soils with artefacts (sub-stances created or significantly modified by humans or sub-stances brought to the surface by human activity andunaltered by pedogenesis), soils with a geomembrane, andsoils with technic hard rock (consolidated material resultingfrom an industrial process). Besides one soil with technichard rock, all the technogenic soils presented during the tourwere characterized by artefacts. Technosols were introducedin 2006 to group together soils with technogenic parentmaterial and limited pedogenesis. The limited pedogenesisis part of the definition of the artefacts. But 20 percent (byvolume, by weighted average) of artefacts within 100 cm ofthe soil surface or to continuous rock (whichever is shal-lower) are sufficient to key out as Technosol. What happensif the rest of the soil volume (may it be of natural or technicorigin) has undergone an advanced pedogenesis? It was acommon opinion that such soils should – contrary to thepresent definition – not be Technosols, and that thereforesome diagnostic horizons and diagnostic properties indicat-ing a more advanced soil formation should be explicitly ex-cluded from Technosols (unless there is a geomembrane ortechnic hard rock in the required depth). In a second stepthe lists of the prefix and suffix qualifiers must be adjustedto the diagnostics which may be present in Technosols. Ad-ditionally, it was questioned whether the fixed limit of 20percent artefacts is appropriate for shallow Technosols or ifa dynamic criterion requiring higher percentages for shal-low soils would be better. During the discussions it was alsopointed out that a differentiation between in-situ accumu-lated (pedogenic) organic carbon and lithogenic organic car-

bon is necessary to avoid erroneous classifications of soilsthat are rich in the latter.

The definitions of the Stagnosols as such seemed to be well.Some criticism was made on the separation of the stagnicproperties (one diagnostic property in WRB of 1998) intoreducing conditions and stagnic color pattern (two diagnos-tic properties in WRB of 2006). A point of serious discus-sions was the differentiation between Stagnosols, Planosols,and Albeluvisols. Stagnosols and Planosols are both formedunder the influence of stagnant water. Albeluvisols showalbeluvic tonguing and may or may not have stagnant wa-ter. The present WRB key gives preference first to theAlbeluvisols and then to the Planosols. The differentiationbetween Planosols and Stagnosols was not regarded to beproblematic as Planosols are easily identified by an abrupttextural change within 100 cm from the soil surface. A topicfor intensive discussion was whether soils with both, analbeluvic tonguing and stagnant water, should belong tothe Albeluvisols or to the Planosols and Stagnosols. A ma-jor argument in favor of the present situation (priority tothe Albeluvisols) was that the coarser-textured tongues areunderstood to control the water regime of the soil. In thefinal discussion, the suggestions for a change in priority didnot succeed but there was an agreement to work on a re-finement of the definition of albeluvic tonguing, especiallyfor those soils where the overlying coarser-textured hori-zon is eroded or disturbed. There was also a criticism onthe name Albeluvisol which was a former political com-promise and, instead of referring to the tongues, gives theerroneous impression that an albic horizon is required andthat the soil (like a Luvisol) must have a high CEC and ahigh base saturation.

Acknowledgements. The Techno-/Stagnosols-Tour was also the 25th

jubilee of the WRB working group, which was initiated from FAO in1980 as a follow up of the 'Soil Map of the World' project and estab-lished in 1982 from the ISSS. We all were glad to have the WRB-veterans R. Dudal und H.-P-Blume with us on the Techno-/Stagnosols-Tour; this, in order to benefit from their long-term memory. Finally, wewant to thank the numerous contributors not mentioned here by namefor their support during the preparation and running of the excursion.Also, we want to thank the generous sponsors, notably the DFG (Ger-man Research Foundation), the Universitätsbund Hohenheim, theFarny- and the Eiselen foundation, the DBG (German Soil ScienceSociety) and the IUSS.

References

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Sauer D, Burghardt W (2006): The occurrence and distributionof various forms of silica and zeolites in soils developed fromwastes of iron production. Catena 65 (3) 247–257

WRB (IUSS Working Group WRB 2006): World Reference Basefor Soil Resources 2006. World Soil Resources Reports 103,FAO, Rome

Zikeli S, Kastler M, Jahn R (2005): Classification of anthrosolswith vitric/andic properties derived from lignite ash. Geoderma124 (3–4) 253–265