Keywords

3.1 Introduction

The launch of the Irish Soil Information System (SIS) in 2014 represented a major advancement in the availability of soil information at a national level in Ireland. A comprehensive inventory of soil data in Ireland compiled in 2007 highlighted that soil data coverage was incomplete in detail and extent (Daly and Fealy 2007), and that an updated soil map was necessary to satisfy a growing demand to meet sustainability targets (Creamer et al. 2014). The Irish SIS project was designed to satisfy this growing need, a key output of which was the development of the 3rd Edition National Soil Map of Ireland, a digital map at a resolution of 1:250,000 (Chap. 4). The Irish SIS combined novel digital mapping techniques with traditional field survey methods and historic soil survey detail, to establish a consistent national legend for Irish soils. A brief overview of the World Reference Base for Soil Resources (WRB) with specific attention to the correlation of the Irish SIS with the WRB classification system is also presented.

As described in Chap. 2, soil formation and development depends upon the interactions of several factors. Soil classification within the Irish SIS recognises these soil forming factors and processes, morphology and soil geographic approaches which have been complemented with laboratory data for verification (Simo et al. 2015). The heterogeneity of soil insists that similar members are grouped together so that the great number of soils, which vary from one another in different degrees of contrast, can be clustered into progressively higher categories (USDA 1960). Thus, soil classification is the process of grouping soils together where a similar range of chemical, physical and biological properties have been observed, into units that can be geo-referenced and mapped. The Irish SIS consists of a three-tiered taxonomy of ‘Great Soil Group’, ‘Subgroup’ and ‘Series’, ordered from the most general to the most specific (Fig. 3.1).

Fig. 3.1
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Three-tiers of soil taxonomy in the 2014 Irish soil classification

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3.2 Reference Section

The reference section refers to the vertical section of the soil profile which is described and classified. Within this section, diagnostic horizons are identified following set principles outlined in the Irish SIS handbook. The depth or thickness of this section varies depending upon the soil parent material . In Irish soil classification, four main reference section depths are recognised:

  1. 1.

    Soils in peat have a reference section that extends from 40 to 80 cm with organic material deeper than 80 cm (Fig. 3.2). Utilising a thickness of 40 cm or more of peat to classify peat soils is consistent with the WRB definition of Histosol (IUSS Working Group WRB 2006). These soils are composed of organic material largely derived of partially decomposed plant remains that accumulated under waterlogged conditions, either formed in situ or as constituents of sub-aquatic sediments such as organic lake muds (Avery 1980).

    Fig. 3.2
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    Reference section for peat soils (from Simo et al. 2014, based upon Clayden and Hollis 1984 p. 13)

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    In peat soil, the mineral fraction has little textural significance as peats are mostly composed of organic materials. Soils with more than 50% organic matter are defined as peats. Soils with less than 50% but greater than 20% organic matter and with 50% or more sand content in the mineral fraction are defined as Sandy Peat, or with less than 50% sand content defined as Loamy Peat. Other criteria for differentiation of soils in peat of less than 50% organic matter: Soils with organic carbon (OC) <20% (calculated by organic carbon analysis), two categories are distinguished; soils with more than 12% OC and more than 50% Sand, they are defined as Peaty sand; and soil with OC >14.5% and amount of clay ≥50%, defined as Peaty loam.

  2. 2.

    Histic Organic soils over bedrock mainly consist of organic material over a layer of coherent bedrock or skeletal products of weathering. These soils extend from the organic soil surface to the upper surface of this bedrock/skeletal layer, whichever is at the shallowest depth (30 cm). The peaty (> 20% OC) O horizon must have a thickness of 7.5 cm or more.

  3. 3.

    Mineral soils over bedrock or lithoskeletal substrate are comprised of mineral material overlying bedrock or skeletal weathered bedrock fragments. This includes two subtypes (Clayden and Hollis 1984): Firstly, where the surface layer is no greater than 30 cm thick, typically occurring as Rendzina or Lithosol soils. Secondly, where the profile depth is greater than 30 cm but bedrock occurs within 80 cm (Simo et al. 2014).

  4. 4.

    All other substrates, which includes any mineral soils comprised in thick drift. In general, soil material must be at least 80 cm thick. These substrates are mostly glacial till or fluvio-glacial deposits and recent alluvium.

3.3 Describing a Soil Profile

Part of the process of describing the soil profile includes a site description. Local landscape description is an important part of the soil classification process. On arrival GPS locational data and the principal landscape features should be recorded, such as relief, topography, aspect and land use (Fig. 3.3). Once the profile pit is dug to a depth of approximately 1.2 m, the profile face must be cleared and photographed, along with recording the parent material . Thereafter, each horizon should be described in detail with characteristics of field estimated texture, structure, colour, carbonates, stone content and type, root content and depth and the presence of biota recorded (Creamer et al. 2014).

Fig. 3.3
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Profile description card to record the site description and horizon detail for each horizon. During the SIS campaign a field tablet with a supporting database and interface was used to record data directly in the field

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In relation to analysing soil profile pits, along with the classification criteria described, a suite of measurements were analysed at horizon level (Table 3.1) to provide a more complete description of the soil profile.

Table 3.1 Sampling of horizons in Irish SIS (Creamer et al. 2014)
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Figure 3.4 (left) shows an open profile pit with three bulk density rings taken per horizon. Final bulk density values are recorded on a horizon basis and reported as an average value (cm3) with standard deviation (σ).

Fig. 3.4
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Three bulk density rings per horizon as a physical soil measurement shown on left, method for bulk density measurements shown on right (Photo: Jeremy Emmet-Booth)

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3.4 Horizon Definitions

When characterising or classifying soil type, it is essential to define the differing layers (horizons) found within the soil profile. This characterisation is done by defining certain characteristics such as structure, colour, porosity, mottling, textural changes, pH , etc. These characteristics are then used to classify genetic horizons. The classification of soils at Subgroup level requires that the various horizons of the soil profile are described and defined. Horizon definitions within the Irish SIS are fully described in the field handbook by Simo et al. (2014). Overall, there are three main horizons, A, B and C that occur in a majority of soil profiles as shown in Fig. 3.5. The A and B horizons constitute the ‘true soil’ whilst the C horizon refers to parent material . Some soils lack a B horizon and are said to have AC profiles. On other soils, organic layers (O horizons) may overlie the mineral horizons. Underlying rock is indicated by the symbol R.

Fig. 3.5
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Source Irish Soil Information System

Sample soil profiles annotated with soil horizon designations.

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Organic horizons

  • Peaty O horizons accumulate under wet conditions. They are saturated with water for at least 30 consecutive days in most years, or have been artificially drained, and include fibrous, semi-fibrous and amorphous peat. Sub-horizons include: Of, Omf, Oh, Op.

  • L horizon represents fresh litter deposited during the previous annual cycle. It is normally loose and the original plant structures are little altered.

  • F, H are organic horizons originating as litter deposited or accumulated at the surface and seldom saturated with water for more than a month at a time. The F has partly decomposed or comminuted litter, remaining from earlier years, in which some of the original plant structures are visible to the naked eye. The H has well decomposed litter, often mixed with mineral matter, in which the original plant structures cannot be seen.

Mineral horizons

  • The A horizon refers to the mineral horizon formed at or near the surface. An A horizon is characterised by incorporated humified organic matter, or by evidence of cultivation, or both. The incorporation of organic matter is presumed to be due to biological activity or artificial mixing. Horizon designations include: Ah, Ap, Ahg, Apg, AB.

  • The E horizon is a subsurface mineral horizon that contains less organic matter and/or dithionite-extractable iron and/or silicate clay than the immediately underlying horizon, presumably as a result of loss or washing out of one or more of these constituents.

  • The B horizon is the mineral subsurface horizon, without rock structure characterised either by illuviation or by an alteration of original material such as the solution and removal of carbonates. Horizon designations that occur include: Bf, Bg, Bh, Bs, Bt, Btg, Bw, Bx, Bk, BC.

  • The C horizon is usually unconsolidated or a weakly consolidated mineral horizon that retains soil structure or otherwise lacks the properties of the overlying horizons. C horizons may have been modified by gleying or by an accumulation of carbonates or soluble salts or they may have developed brittleness and associated properties of fragipans. Horizon designations include: Cu, Cr, Ck, Cg.

Many soils are subdivided on the basis of a significant difference within the main horizons. These differences are identified by the horizon designation accompanied by a suffix identifier (Table 3.2). Where lithological discontinuity occurs and two different geologic parent material s are present, the number ‘2’ is placed in front of the horizon symbol for horizons developed in the second parent material .

Table 3.2 Suffix and definition
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3.4.1 Diagnostic Criteria

Table 3.3 describes the criteria for the diagnostic features included in the Irish SIS for the classification of soils at Subgroup level.

Table 3.3 Diagnostic features to classify soil subgroup
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3.5 Classification of Great Soil Groups

Great Soil Groups represent the most general soil classification unit in the Irish SIS . Great Soil Groups are organised based upon the dominant soil forming factors. Soils within Great Soil Groups have common characteristics and soil forming conditions; they are developed under the influence of environmental factors (vegetation and climate) active over a considerable geographic range and have one or more Subgroups of soil. Soils occurring in a Great Soil Groups have the same arrangement and degree of expression of horizons in the soil profile. In Ireland, 11 Great Soil Groups have been identified and are coded 01–11: (01) Ombrotrophic Peat Soils ; (02) Mineratrophic Peat Soils ; (03) Rendzina ; (04) Lithosols ; (05) Alluvial Soils ; (06) Groundwater Gleys ; (07) Surface-water Gleys ; (08) Podzols ; (09) Brown Podzolic ; (10) Luvisols and (11) Brown Earths . The following key allows a simplified determination of Great Soil Group within the Irish SIS by following a quick yes/no system that is applied from the top to the bottom. The most distinguishing features are at the top of the key, and Brown Earths are at the bottom representing the group with the fewest distinguishing features (Fig. 3.6).

Fig. 3.6
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Key to determine Great Soil Group classification based upon Irish SIS Classification 2014

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This key is based upon the following principles, with criteria synthesised in Table 3.4:

Table 3.4 Sequencing of Great Soil Groups (Simo et al. 2014)
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  • Organic soils are first differentiated from mineral soils and are further defined on the basis of whether they are rain-fed (Ombrotrophic peat) or groundwater-fed systems (Minerotrophic peat). If pH  is <4 they are Ombrotrophic. If pH  >4 they are classified as Mineratrophic peat soils .

  • Next shallow soils (<30 cm) with a severe limitation to rooting are identified as Lithosol or Rendzina soils. If the soil pH is >7, or if the presence of calcium carbonate (CaCO3) is induced by a hydrochloric acid (HCl) (10%) reaction these soils are classified as Rendzina soils.

  • Thirdly soils that are influenced by water are identified due to the presence of mottling in the soil profile. If the profile shows stratification associated with fluvial transport and deposition, these soils are classified as Alluvial soils. If there is no evidence of Alluvial bands, the profile is checked for a groundwater influence. This should be clearly observed within the surface 40 cm. If present, the profile will exhibit a grey uniform colour throughout the profile and these soils are classified as Groundwater Gleys . These are typically influenced by location and are often found near rivers or inter-drumlin hollows where the water table is high. If no groundwater influence is found, these soils are classified as Surface-water Gleys which are poorly drained due to presence of a slowly permeable subsurface layer.

  • If the profile has not been influenced by water, the profile is next checked for iron (Fe) and/or aluminium (Al) chemistry. Where Fe and Al have played a major role in the soil formation, soils are classified as Podzols and Brown Podzolic s. Where an obvious E horizon exists, indicating a zone of eluviation is present, these soils are classified as Podzols . This is evidenced by the presence of a bleached white sandy layer. Soils where no E horizon is evident, but where clear Fe/Al accumulation has occurred in the Bs horizon are defined as Brown Podzolics.

  • Step five, soils with clay illuviation from surface and/or sub-surface horizons to lower down the profile are classified as Luvisols . These soils have an increase of clay in the lower horizon by 20% (presence of a Bt horizon).

  • Finally, Brown Earths which are relatively young soils or soils with limited profile development are identified and represent the group with no clear distinguishing features.

Soils vary due to a suite of soil forming factors and processes, including topography (see Chap. 2). As a result, the catena sequence of soils varies from hilltop to valley floor. As the Irish SIS considers these soil forming factors and processes, a generalised description of the soil catena sequence can be presented (Fig. 3.7) with the 11 Great Soil Groups of Ireland described across a landscape position.

Fig. 3.7
figure 7

Great Soil Groups described across a landscape position (Simo et al. 2014)

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3.6 Classification of Soil Subgroups

The second level of classification in Irish SIS is the Soil Subgroup. Altogether, the Irish SIS contains 67 Subgroups, based upon the diagnostic features found within the 11 Great Soil Groups. The character of the various horizons in the soil profile, reflect the influential processes of soil formation that represent the true characteristics of a soil that are important for its use and management. Diagnostic features are soil properties that describe soil characteristics and are used to classify the Soil Subgroup.

Altogether nine main diagnostic features are included in the Irish SIS , coded 1–9 (Fig. 3.8). 0 is also included in the classification key and indicates that there are no additional distinguishing characteristics present. The Irish SIS has developed a key based upon the following principles:

Fig. 3.8
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Key codes applied according to the subgroups and diagnostic features

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  1. 1.

    The first number in the code refers to the Great Group (01–11) following the key system (Fig. 3.6).

  2. 2.

    The second number is the dominant diagnostic feature (Fig. 3.8) code (0–9).

  3. 3.

    The third number is the secondary diagnostic feature code (0–9) (Fig. 3.8).

The nomenclature at Subgroup level provides the most information on the soil processes, as Subgroups are named on the basis of the most important features that occur in the reference section to a maximum of two, described as additional features to the Great Soil Group. For example, a Humic Calcareous Brown Earth is coded as 11.5.6 (Fig. 3.8) where 11 indicates the Great Group; the soil is predominantly calcareous (within 40 cm) indicated by a five, 11.5 and finally, the soil also has a humose surface horizon represented by a six, therefore: 11.5.6. Figure 3.8 shows the Subgroups that exist within Irish SIS .

3.7 Classification of Soil Series

Soil Series is the final level of classification and represents the most specific category in the taxonomy. In Ireland, of the final 213 Soil Series classified, 73 originated and were described by the AFT soil survey. Series are defined on the basis of the following hierarchy; Great Soil Group, Soil Subgroup, texture and parent material . Series names are derived from the place names, such as town lands, from where the soil was first defined or where it was best expressed. Soil Series are identified by a unique code made by concatenating the Subgroup code with a code based upon the series name; for example, ‘Ballylanders’ is a Typical Brown Earth (1100) and has a map code ‘BY’, hence the unique full series code is ‘1100BY’ (Simo et al. 2013).

Texture refers to the relative proportions of the various sized particles in the mineral fraction of the soil, specifically the sand, silt and clay less than 2 mm in diameter (Gardiner and Radford 1980). Texture is described at horizon level. Soil texture is one of the most important physical characteristics of the soil due to its influence on soil properties, such as moisture retention. The Irish SIS applied the particle-size distributions as adopted by USDA (Fig. 3.9) to maintain consistency with earlier soil survey work carried out by AFT. Particle sizes are described as follows: sand (2 mm–50 picometre (pm)), silt (50–2 pm), and clay (<2 pm) sized particles.

Fig. 3.9
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Chart with percentages of clay (<0.002 mm) silt (0.002–0.05 mm) and sand (0.05–2.0 mm) in the basic soil texutre classes (Soil Survey Staff 1993)

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Overall soil profile texture:

Four broad particle-size groupings are defined for generalising the overall texture of the reference section; sandy (Sy), loamy (Ly), silty (Zy) and clayey (Cey). When describing the total profile, as opposed to individual horizons, texture is described on the basis of particle size classes (Fig. 3.10). For agriculturally important soils, the loamy and silty groups are further subdivided into coarse and fine categories. To define the soil as either coarse (cLy) or fine loamy (fLy) the dominant texture within 80 cm should be used to define the broad textural class. The following procedures are applied (Jones et al. 2014):

Fig. 3.10
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Soil particle-size classes and broad groups for Soil Series definition (Jones et al. 2014) used in Irish soil classification 2014

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  1. 1.

    if topsoil ~40 cm thick cLy over fLy, classify soil as cLy

  2. 2.

    if topsoil ~40 cm thick fLy over cLy, classify soil as fLy

  3. 3.

    if topsoil <40 cm thick fLy over cLy, classify soil as cLy

  4. 4.

    if topsoil <40 cm thick cLy over fLy, classify soil as fLy

In the Podzol and Lithosol Great Soil Groups, no distinction is made between coarse and fine loamy and Soil Series are described as Sandy, Loamy or Clayey (in Lithosols only).

Parent material is also used to define the Soil Series unit. Substrates in Ireland occur in five different states; peat, bedrock, drift, alluvium and anthropogenic (Table 3.5).

Table 3.5 Substrate types used to define soil series in Ireland (Simo et al. 2014)
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Peat is a biogenic deposit having developed in the post-glacial period of the last 10,000 years. Three main peat formations are recognised in Ireland (1) raised bogs of the Central Plain; (2) blanket bogs of the western seaboard and upland regions and (3) fen peat. Their genesis has been influenced by drainage, climate, hydrology, geomorphology, nutrient status and glacial geology but over time, these deposits have also been altered by man’s activities.

Bedrock is the hard rock beneath surface materials such as soil and gravels. These soils comprise mineral material overlying a layer of coherent bedrock, or skeletal weathered bedrock fragments (that are at least 15 cm thick and begins above and extends below 80 cm depth). Where possible, effort to distinguish between bedrock and skeletal substrates should be made.

Drifts, the third substrate group, are composed mostly of Quaternary deposits including glacially-derived tills and fluvioglacial deposits and recent alluvium. The main classes of drift in Ireland found are: (1) drift with siliceous stones with deposits dominated by sandstone, slate, shale or chert stones. Soils in this substrate are usually non-calcareous to at least 120 cm; (2) drift with limestones that have calcareous material within 80 cm depth, or a non-calcareous B horizon within 80 cm but that passes conformable within 120 cm into calcareous material; (3) drift with igenous and metamorphic stones where these constitute the dominant local lithology and, (4) stoneless drift soils.

Alluvium substrate are soils that include all thick drifts in which loamy or clayey marine, river, or lacustrine sediments of recent age extend below 30 cm depth (Avery 1980) of which three types are used to define Soil Series; river alluvium, marine/estuarine alluvium and lake marl. However, the distinction between each type is not always clear because intrinsic properties such as structure, porosity, pH , CaCO3 content, exchangeable cations and colour do not provide a consistent means of identification.

3.8 Correlation of Irish SIS to World Reference Base

Global population growth, land degradation and climate change, along with the interdependence of countries for the supply of food and agricultural produce, prompted the need for a global harmonised soil information system. On this basis the Food and Agriculture Organization of the United Nations (FAO) called on the active participation of the soil community to come together to develop a framework for the harmonisation of existing soil classification systems (IUSS Working Group WRB 2006). The first meetings were held in 1980 and 1981, hosted by the Poushkarov Institute of Soil Science and Yield Programming in Sofia, Bulgaria. At the first meeting it was decided to launch a programme to develop an International Reference Base for Soil Classification (IRB). At the second meeting, the general principles of the joint programme towards the development of the IRB were defined (IUSS Working Group WRB 2006). In 1992, the IRB was renamed the World Reference Base (WRB), with the working group established at the 15th Congress of ISSS. The work culminated in the release of the first edition of the WRB for soil resources at the 16th World Congress of Soil Science at Montpellier in 1998. A second edition was subsequently released at the 18th World Congress at Philadelphia in 2006. The first edition comprised of 30 Reference Soil Groups (RSGs) with the second edition including 32 RSGs. Following a period of eight years, and an intensive worldwide testing and data collection effort, the third edition was launched in 2015 to reflect new updates and the earlier drafts and editions of the WRB (IUSS Working Group WRB 2015).

The development and revision of the publication of the WRB for soil resources has greatly contributed to a better understanding of soil science and has been used by the European Commission as the basis for harmonised assessment for the European Union and beyond. Many countries have adopted the WRB as a higher level to their national soil classification system (Reidy et al. 2014). The WRB was not designed as a national classification system but rather to serve as a mechanism for harmonisation to facilitate communication at an international level.

In the Irish SIS Final Technical Report 8, Reidy et al. (2014) describe the correlation of the Irish soil classification system to the WRB 2006 system. During the SIS field campaign 225 soil pits were described in detail with samples analysed to 1 m depth. The description and the associated analytical data were completed with consideration of correlation to the WRB system (Reidy et al. 2014). Within WRB, two categorical levels are defined: the 1st level contains the 32 RSGs with groups of soils based upon dominant identifiers such as soil forming factors or processes that indicate the soil condition. The RSG represent all major regions of the world. The 2nd level includes prefix and suffix qualifiers that are added to the RSG to allow precise characterisation and classification of individual soil profiles (Reidy et al. 2014). Within WRB the classification of soils is based on soil properties defined in terms of diagnostic horizons, properties and materials that take into account their relationship with soil forming processes. Diagnostic features are then included that are of significance to soil management and should be selected, to the extent possible, at a high level of generalisation. Similarly, within the Irish SIS , classification at Great Soil Group level considers the main soil forming processes with classification at Soil Subgroup level taking diagnostic criteria into account. Table 3.6 by Reidy et al. (2014) shows the RSG that Irish Great Soil Groups are correlated to. For example, Irish Great Soil Group 01, Ombrotrophic Peat correlates with RSG Histosol, with the Ombric suffix qualifier. A full table of the current WRB correlation for each representative soil profile at Soil Series level is also available from Reidy et al. (2014).

Table 3.6 Soil great group code and soil group in Irish classification and correlation to the WRB (Reference Soil Group) from Reidy et al. (2014) with dominant WRB reference group in bold
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While some WRB prefix and suffix qualifiers may not so readily correlate and might require laboratory data not measured in the SIS, currently most Great Soil Groups readily correlate with the RSG of the WRB. The WRB is an on-going evolving process and correlation of the Irish SIS with WRB designations is important for collaboration and the presentation of work at an international level.

3.9 WRB Classification for Urban Soils

Concepts for discussing urban soils have been developed by the SUITMA series of conferences (Soils of Urban, Industrial, Transport, Military and Mining Areas), and by ICOMANTH (International Committee on Anthropogenic Soils of the United States Department of Agriculture). In relation to classification, many informative names for urban soils come from the WRB for Soil Resources (IUSS Working Group WRB 2015). The WRB for Soil Resources includes many concepts that can help with describing urban soils, and how to recognise human action in soils everywhere. “Transportic”, “Relocatic” and “Aric” qualifiers in soil names refer to soil moved long distances (such as in trucks), short distances (using diggers), and mixed without moving, so soil layers are disrupted. These transformations occur during construction, but also in many historical agricultural operations such as burying dead animals, bringing up limestone to spread on the land surface, installing and removing drains and earthbanks. Soils that have been mixed do not have horizons, and are called Regosols. The soil name “Technosol” was coined in 2006, and represents soils with sealing (including by buildings and roads, carparks and other “pavements”) OR soils with a high proportion of artefacts (including all products of manufacture, wastes, ash, oil, and mine spoil). A narrower concept is Ekranic Technosol, with the “Ekranic” qualifier specifically referring to soils sealed by constructed rock-like material such as concrete, tarmacadam or asphalt. This qualifier is only associated with the Technosol group and goes before the name, as do qualifiers for intermediates between groups. Further qualifiers are listed in brackets after the name, giving very informative soil names. Table 3.7 provides an example of an urban soil type, using the WRB approach to naming:

Table 3.7 Garbic Ekranic Technosol (Densic, Toxic, Transportic) based upon definitions of formative elements for second-level units of WRB from IUSS (2015)
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The Garbic Ekranic Technosol (Densic, Toxic, Transportic) soil is primarily a Technosol. It has two characteristics typically associated with Technosols, the more-important one being that it is sealed by a “technic hard” material such as concrete or asphalt (Ekranic), and secondly that it includes a significant amount of material derived from organic wastes (Garbic). The order of Irish SIS nomenclature is consistent with the order described here for the WRB. Further characteristics identifiable under field conditions are listed, in alphabetical order. The soil is denser than will allow growth of roots (Densic); it contains substances toxic to organisms (Toxic); and it has been moved from another site (Transportic).

A few more examples show some variation among urban soils:

Arenosol (Relocatic)

Regosol (Densic, Technic)

Spolic Technosol (Thapto-Fluvisolic)

Arenosol is a sandy soil, while Relocatic identifies it as having been reconstructed without being removed from the site. A Regosol is a soil with no distinct horizons from soil-formation processes; Technic shows it as having significant artefact content (but not enough to qualify as a Technosol). Spolic Technosols represent industrial waste or mine spoil, while Thapto-Fluvisolic identifies underlying buried (Thapto-) sediment derived from flowing water (Fluvisol[ic]).

The full system, for naming all soils in the world, is published by IUSS Working Group WRB (2015). Examples of urban soils with their WRB names are given in Fig. 3.11.

Fig. 3.11
figure 11

Urban soils. a Ekranic Technosol, a pavement with constructed deposits below, formerly a tramline, road base, and embankment. b Regosol, formed during soil relocation as cut-and-fill for highway construction; this will eventually be given a topsoil cover and grass seed sown. c Garbic Technosol (Thapto-Fluvisolic), reclamation deposits of commercial garbage, with many artefacts such as bottles; beach sediments lie a further 80 cm below the base of this hand-dug pit. d Regosol (Relocatic), a reclamation deposit over a worked-out sand pit, showing remnants of former site soils, roughly mixed

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