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Cambisol
Cambisol
Cambisol
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Calcaric Cambisol (Humic) profile in Des'a forest in Ethiopia

A Cambisol in the World Reference Base for Soil Resources (WRB)[1] is a soil in the beginning of soil formation. The horizon differentiation is weak. This is evident from weak, mostly brownish discolouration and/or structure formation in the soil profile.

Distribution of Cambisols

Cambisols are developed in medium and fine-textured materials derived from a wide range of rocks, mostly in alluvial, colluvial and aeolian deposits.

Most of these soils make good agricultural land and are intensively used. Cambisols in temperate climates are among the most productive soils on earth.

Cambisols cover an estimated 15 million square kilometres worldwide. They are well represented in temperate and boreal regions that were under the influence of glaciation during the Pleistocene, partly because the soil's parent material is still young, but also because soil formation is comparatively slow in the cool, northern regions. Cambisols are less common in the tropics and subtropics, but they are common in areas with active erosion where they may occur in association with mature tropical soils.

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Cambisol

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Cambisols are a major reference soil group in the World Reference Base for Soil Resources (WRB), defined by the presence of a cambic horizon (Bw) starting within 100 cm of the mineral soil surface, which exhibits evidence of pedogenic alteration such as structural development, color changes, or partial without significant accumulation of clay, , or other diagnostic materials. This horizon, typically yellowish-brown to reddish and at least 15 cm thick, indicates an early to moderate stage of soil formation from parent materials like , , or , and the soils lack more advanced features such as argillic or spodic horizons. Derived from the Latin cambiare meaning "to change," Cambisols represent soils in transition, often with an ABC profile sequence where the surface A horizon may be ochric, mollic, or umbric. These soils typically have a loamy to clayey texture, good aggregate structure, and moderate water-holding capacity, with pH ranging from acidic (4–6) to neutral or slightly alkaline (6–8) and base saturation varying widely, influencing their fertility. They contain weatherable minerals and free iron oxides from oxidative processes, but show only slight clay illuviation or carbonate removal, and may exhibit weak redoximorphic features in poorly drained variants. Qualifiers such as eutric (high base saturation), dystric (low base saturation), chromic (strong color), or gleyic (water saturation) further specify subtypes based on chemical, physical, or environmental properties, allowing for over 100 possible combinations in the WRB system. Globally, Cambisols cover approximately 1.5 billion hectares, accounting for about 12% of the world's ice-free land surface, and are particularly widespread in temperate and boreal regions, including post-glacial landscapes of and , as well as mountain areas like the , , and . They also occur in humid subtropical highlands, young alluvial plains (e.g., Ganges-Brahmaputra delta), and eroding terrains, though less commonly in arid or strongly weathered tropical lowlands. Agriculturally significant, eutric Cambisols support productive cropping and due to their inherent , while dystric variants require amendments for arable use; however, steep slopes pose risks, often limiting them to or .

Definition and Characteristics

Definition

Cambisols are defined within the World Reference Base (WRB) for Soil Resources as soils showing moderate pedogenesis, primarily identified by the presence of a cambic horizon that begins within 100 cm of the mineral soil surface and exhibits evidence of alteration relative to the underlying . This cambic horizon, a subsurface layer at least 15 cm thick, displays weak brownish discoloration, development, or other signs of , such as color changes (e.g., higher chroma or redder hue in at least 90% of the exposed area) or an absolute increase in clay content of at least 4% compared to adjacent layers, without qualifying as a more developed diagnostic horizon like an argic or spodic. The horizon consists of mineral material that is sandy or finer in texture, with soil aggregate present in at least 50% of the fine-earth volume by volume. In addition to the cambic horizon, Cambisols may be characterized by a mollic horizon overlying a subsoil that has less than 50% base saturation (by 1 M NH₄OAc at 7) within 100 cm of the surface, provided no other overriding diagnostic features are present. These soils lack significant accumulations of illuviated clay, , soluble salts, or iron and aluminum oxides that would assign them to other reference soil groups, ensuring the cambic horizon remains the principal diagnostic attribute. Exclusions include properties such as vertic structure, gleyic color patterns within 50 cm of the surface, or salic, calcic, or gypsic horizons starting within specified depths. The typical profile of a Cambisol follows an ABC sequence, featuring an ochric, mollic, or umbric A-horizon over a yellowish-brown to red cambic B-horizon, with the C-horizon representing relatively unaltered below. This configuration reflects transitional soil development, where the cambic horizon serves as a marker of moderate and horizon differentiation without advanced profile complexity.

Key Properties

Cambisols exhibit a range of physical properties that reflect their moderately developed nature, with textures typically ranging from loamy to clayey, often including silty or sandy variants depending on . The structure is generally favorable, featuring weak to moderate development with subangular blocky or granular peds in the subsurface horizon, where at least 50% of the fine earth volume shows aggregate formation due to incipient . Colors vary from yellowish-brown to reddish hues, resulting from formation and pedogenic changes, with the subsurface layer often displaying a chroma at least one unit higher or a hue at least 2.5 units yellower or redder compared to the underlying material when moist. These soils are usually deep to moderately deep, with the key subsurface horizon starting within 100 cm of the surface and extending at least 15 cm thick, and they lack impermeable layers within 100 cm, promoting well-drained to moderately well-drained conditions unless affected by or . Chemically, Cambisols contain a high proportion of weatherable minerals with slight to moderate , and no significant accumulation of illuviated clay or . Base saturation varies, classified as eutric when exceeding 50% or dystric when below 50% in the specified layers, while is typically neutral to slightly acidic, often around 6 in representative profiles. Organic matter content is moderate, concentrated in surface horizons with levels up to 1% or more in humic variants, supporting aggregate stability without dominant accumulation. For example, in a Silti-Chromic Cambisol from deposits in (ISRIC reference soil CN 034), the profile features a reddish brown silt loam texture at 65 cm depth, overlying truncated material from slope wash, illustrating the typical loamy texture and color development in such soils.

Formation and Distribution

Soil Formation Processes

Cambisols develop through incipient pedogenic processes that mark an early to intermediate stage of soil evolution, characterized by the formation of a cambic horizon resulting from initial and structural changes in the subsoil. This horizon emerges from the weak alteration of primary minerals, particularly ferromagnesian minerals like and , through in oxidizing, weakly acidic conditions. The process releases iron, which oxidizes to form ferric oxides and hydroxides such as and ; these coat particles, imparting yellowish-brown to reddish colors and promoting the aggregation into blocky or prismatic structures. As a transitional soil type, Cambisols often form on unconsolidated parent materials such as , , or glacial deposits, where ongoing or depositional rejuvenation prevents further horizon development and maintains the soil in a relatively young state. In these settings, the limited depth and intensity of reflect a balance between soil-forming processes and geomorphic instability, with erosion removing surface material and resetting pedogenesis. Key environmental factors influence Cambisol formation, including cool to temperate climates that slow mineral weathering due to lower temperatures and reduced , adequate drainage that facilitates oxidation and precipitation, and vegetation cover that supplies to the surface horizons, enhancing initial . These soils typically develop over hundreds to thousands of years in environments where pedogenesis is constrained by young age, low temperatures, or resistant parent materials like or volcanic rocks. Unlike more advanced soils such as Luvisols or Podzols, Cambisols exhibit weak horizonation because insufficient time or energy limits processes like significant clay illuviation or translocation, resulting in only subtle subsurface modifications without pronounced layering.

Global Distribution

Cambisols cover an estimated 1.5 billion hectares worldwide, representing a significant portion of the Earth's continental land area. They are particularly prevalent in temperate and boreal zones, including post-glacial landscapes across and , as well as mountain regions throughout the world such as the , Carpathians, Appalachians, , and highlands in and . Additionally, Cambisols occur on young alluvial plains and terraces, notably in the Ganges-Brahmaputra delta and various European river valleys. These soils are commonly associated with humid to subhumid temperate climates, where moderate rates allow for their development without rapid evolution into more advanced soil types. They are less frequent in the and , owing to accelerated processes that typically lead to more differentiated profiles, and are rare in arid regions or polar extremes due to limited and extreme temperatures. Topographically, Cambisols favor erosion-prone slopes, , and areas with resistant parent materials such as or , which contribute to their relatively young and underdeveloped nature. Notable examples include their widespread presence on the Russian Plain, in the , and across the Andean highlands. In , a Silti-Chromic Cambisol serves as a key reference soil, illustrating typical characteristics in loess-derived landscapes.

Classification

WRB Classification

Cambisols are one of the 32 reference soil groups (RSGs) in the World Reference Base for Soil Resources (WRB), an international system developed by the International Union of Soil Sciences (IUSS). They encompass soils with little or no profile differentiation, and are characterized primarily by the presence of a cambic horizon—a subsurface horizon showing evidence of alteration through pedogenic processes such as structure development, color change, or removal of carbonates, but without advanced features like significant clay accumulation. The cambic horizon must start within 100 cm of the soil surface, have a thickness of at least 15 cm, and consist of mineral material with sandy loam or finer texture, excluding materials like claric drift. In the WRB hierarchical structure, Cambisols are defined at the RSG level as soils that do not qualify for other groups due to the absence of more developed diagnostic horizons or properties. They exclude soils with argic (clay accumulation), spodic ( and Fe/Al oxides), histic (organic), or other advanced horizons starting within 100 cm of the surface, as these indicate greater pedogenic development and precedence in classification. Diagnostic requirements specify no overlying or underlying layers with accumulated clay, , salts, or Fe/Al oxides that would qualify for other RSGs; subsurface horizons must meet specific texture (e.g., ≥50% fine earth with aggregate structure) and thickness criteria to confirm the cambic nature. Cambisols in the WRB correspond closely to in the , both representing soils with incipient horizon development. In the FAO/ Soil Map of the World legend, they align with the Cambisols group, including subtypes such as Calcaric or Calcic Cambisols based on properties like content. The WRB for Cambisols was first established in the 1998 edition, released at the 16th World Congress of in , providing a standardized framework for global soil correlation. Subsequent updates in 2014 refined depth requirements for diagnostic horizons and incorporated additional pedogenic features, while the 2022 fourth edition maintained core criteria with minor adjustments to inclusions like tsitelic horizons, enhancing precision without altering the fundamental exclusions.

Subtypes and Qualifiers

Cambisols are subdivided using prefix and suffix qualifiers in the World Reference Base (WRB) system to denote specific diagnostic properties or intergrades that refine their classification. Prefix qualifiers, placed before the reference soil group name, primarily indicate the presence of particular horizons or materials influencing soil development. For instance, the Andic qualifier applies to Cambisols with a layer ≥15 cm thick exhibiting andic properties—such as low bulk density (≤0.90 kg dm⁻³ air-dried), high pyrophosphate-extractable Al + ½Fe (≥2.0%), and phosphate absorption (≥85%)—typically derived from volcanic ash, starting within 100 cm of the surface. Similarly, the Vertic qualifier denotes soils with vertic properties, including a clay content ≥30%, evidence of shrink-swell dynamics like cracks or slickensides, and a prismatic or angular blocky structure in a horizon ≥25 cm thick starting between 25 and 100 cm depth. The Vitric qualifier specifies Cambisols influenced by volcanic glass, featuring a ≥15 cm layer with ≥5% volcanic glass shards by volume within 100 cm, often with andic-like properties but lower Al/Fe contents. Other notable prefix qualifiers include Petroplinthic, which indicates indurated plinthite (petroplinthite) occupying >50% of the volume within 50-100 cm depth, and Salic, signifying secondary salt accumulation with an electrical conductivity >15 dS m⁻¹ in a salic horizon starting between 50 and 100 cm. Suffix qualifiers, appended after the reference soil group, describe chemical, color, or organic characteristics of the cambic horizon or upper profile. The Eutric suffix is used for Cambisols with base saturation ≥50% (by NH₄OAc 7) in the cambic horizon or the major part of the upper 100 cm, indicating higher fertility due to greater exchangeable base cations. In contrast, the Dystric suffix applies to those with base saturation <50% in the same layers, often reflecting acidic conditions and lower nutrient availability from leaching of bases. The Calcic qualifier denotes the presence of secondary carbonates (>15% CaCO₃ equivalent by weight or >5% by volume) in a calcic horizon within 100 cm, enhancing . Chromic specifies a cambic horizon with high chroma (≥4 when moist) due to iron oxides, typically redder than 7.5YR hue, signaling oxidation in well-aerated conditions. The Humic suffix indicates elevated organic carbon (≥1%) and dark colors (Munsell value ≤4 and chroma ≤3 when moist) in the upper 25 cm or cambic horizon, promoting fertility in humid environments. Depth-based qualifiers further specify the positioning of these features relative to the surface. For example, andic, vertic, and vitric properties must occur in horizons starting between 25 and 100 cm depth to qualify, avoiding superficial influences that might reclassify the soil. Plinthic and salic qualifiers require the respective horizons to initiate between 50 and 100 cm, distinguishing them from more developed soils like Plinthosols or Solonchaks. Representative examples illustrate these qualifiers' applications. Eutric Cambisols, with their higher base saturation, support intensive agriculture in fertile alluvial plains, while Dystric Cambisols, being more acidic, often require liming for crop production in humid regions. A specific case is the Silti-Chromic Cambisol (Eutric) found in China (ISRIC reference soil CN 034), characterized by silty textures, reddish chromic B horizon, and eutric fertility, occurring in temperate loess plateaus suitable for wheat and maize cultivation. These qualifiers serve to tailor the broad Cambisol category to local pedogenic and environmental variations, facilitating precise soil mapping, assessments, and targeted strategies.

Uses and Management

Agricultural Applications

Cambisols are widely utilized in due to their moderate development and , which facilitate penetration and retention. Eutric Cambisols, characterized by higher base saturation and availability, rank among the most productive soils globally, particularly in temperate zones, supporting intensive cultivation of cereals, , and pastures. These soils exhibit good from inherent mineral reserves, enabling yields comparable to more mature soil types without excessive inputs. Common agricultural applications include cropland in temperate regions, such as production on eutric and dystric subtypes across European plains, where long-term experiments demonstrate sustainable yields with balanced fertilization. In mountainous areas, dystric Cambisols support for , leveraging their depth for grasses, while in boreal zones, they underpin operations alongside limited use. Vertic and calcaric subtypes in irrigated dry zones are employed for and crops, including annual and varieties. Despite their versatility, limitations affect productivity; dystric subtypes often suffer from acidity and , necessitating liming to raise and enhance nutrient uptake, as evidenced by studies showing improved availability and reduced exchangeable aluminum post-application. In erosion-prone locations, such as sloped terrains, is essential to minimize loss and maintain , with research on calcic Cambisols confirming reduced rates under no-till practices. Representative examples highlight their economic role: intensive rice-wheat farming on young alluvial Cambisols in the sustains high productivity for millions, contributing to regional . thrives on chromic Cambisols in Mediterranean hills, where their well-drained profiles support grape quality in areas like . Overall, Cambisols underpin global , especially in developing regions with young, fertile profiles covering about 1.5 billion hectares, bolstering in temperate and subtropical areas.

Soil Management Practices

Cambisols, particularly those on slopes, are susceptible to , which can rejuvenate profiles by removing upper horizons; effective control measures include contour farming, terracing, and planting cover crops to reduce runoff and sediment loss. Contour farming aligns crop rows with landscape contours to slow flow, while terracing creates level benches on inclines to intercept runoff, both proven to minimize displacement in sloping Cambisols. Cover crops, such as or grasses, provide vegetative barriers that stabilize and suppress rates by up to 38% in managed systems. Fertility management in Cambisols varies by subtype; for dystric variants with low base saturation, lime application mitigates acidity, raises , and enhances availability like and calcium. Organic amendments, including and , are essential for maintaining levels, improving and microbial activity in Cambisols under intensive use. In eutric subtypes with higher initial fertility, balanced mineral fertilizers—combining , , and at moderate doses (e.g., 80 kg ha⁻¹ each)—sustain productivity without excessive acidification. Sustainable practices for Cambisols emphasize long-term ; preserves aggregate structure and reduces losses to as low as 0.82 Mg ha⁻¹ yr⁻¹ compared to conventional . integrates diverse species to prevent depletion and enhance cycling. In semi-arid Cambisols, supplemental with integrated strategies, such as and hedges, minimizes water stress while curbing leaching. Cambisols contribute to environmental goals through their moderate organic content, which supports when augmented by organic amendments, potentially increasing organic carbon stocks by 50-110% over a decade in reclaimed variants. In forested Cambisols, management practices that limit disturbance protect belowground , including mycorrhizal networks and essential for cycling. Challenges in Cambisol management include intensified from climate change-driven extreme rainfall, which may significantly increase yields in vulnerable areas. Recent modeling as of 2025 projects increases up to 237% under certain climate scenarios in regions with Cambisols, underscoring the need for enhanced adaptation measures like improved and cover cropping. Irrigated semi-arid variants require vigilant monitoring for salinization, as poor water management can elevate salt accumulation in zones, threatening long-term viability. For calcic qualifiers, drainage improvements may be needed to address waterlogging risks.

References

  1. https://wrb.isric.org/files/WRB_fourth_edition_2022-12-18.pdf
  2. https://www.fao.org/4/y1899e/y1899e08.htm
  3. https://ees.kuleuven.be/soil-monoliths/wrb-documentation-centre/wrb-reference-soil-groups/CAMBISOLS-Lecture-notes.pdf
  4. https://isric.org/all-about-soil/cambisols/
  5. https://files.isric.org/public/documents/WRB_fourth_edition_2022-12-18.pdf
  6. https://www.fao.org/4/as360e/as360e.pdf
  7. https://ees.kuleuven.be/soil-monoliths/wrb-documentation-centre/wrb-reference-soil-groups/CAMBISOLS-Historical-Review.pdf
  8. https://pmc.ncbi.nlm.nih.gov/articles/PMC5274616/
  9. https://ui.adsabs.harvard.edu/abs/2010FCrRe.115..191H/abstract
  10. https://pmc.ncbi.nlm.nih.gov/articles/PMC9982607/
  11. https://www.sciencedirect.com/science/article/abs/pii/S0167198720305663
  12. https://www.e3s-conferences.org/articles/e3sconf/pdf/2018/25/e3sconf_terroircongress2018_01011.pdf
  13. https://www.sciencedirect.com/science/article/pii/S2095633923000424
  14. https://onlinelibrary.wiley.com/doi/full/10.1155/aess/9969088
  15. https://www.researchgate.net/publication/328128539_Improvement_of_Soil_Physical_Properties_of_Cambisol_Using_Soil_Amendment
  16. https://www.sciencedirect.com/science/article/pii/S112547182400361X
  17. https://www.rbcsjournal.org/article/water-erosion-in-a-long-term-soil-management-experiment-with-a-humic-cambisol/
  18. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0134244
  19. https://www.sciencedirect.com/science/article/pii/S0016706119301909
  20. https://www.researchgate.net/publication/370835262_Case_Study_on_Ecosystem_Biodiversity_Conservation_Using_the_Solutions_Adopted_by_a_Forest_Management
  21. https://link.springer.com/article/10.1007/s43621-025-01667-y
  22. https://bsssjournals.onlinelibrary.wiley.com/doi/10.1111/ejss.12742
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