Anderson, D. W. and Smith, C. A. S. 2011. A history of soil classification and soil survey in Canada: Personal perspectives. Can. J. Soil Sci. 91: 675-694. This paper presents an overview of soil classification and soil survey in Canada based on both historical documentation and the personal experiences and perspectives of the two authors. The first soil surveys in Canada beginning in Ontario in 1914 are described along with the earliest systems of soil classification. The roots of the current system of soil classification in Canada can be traced back to the establishment of the first meeting of the National Soil Survey Committee (later the Canada Soil Survey Committee) held in Ottawa in 1945. The Committee met every 2 to 3 years and a hard-cover “first” edition, “The Canadian System of Soil Classification” was published in 1978 and a slightly revised second edition in 1987. The third edition (1998) includes a more complete key and a tenth order, the Vertisolic Order. The four to five decades starting in the late 1940s were the glory years for soil survey in Canada, with well-funded and productive programs in all provinces and territories, with major outputs like the Canada Land Inventory. The period between mid 1990s and 2010 saw declining activity in new field survey and reductions in staff levels by government agencies, but a rise in private sector soil survey, largely for environmental assessment purposes. There is a renewed and on-going interest in and need for soil information. The challenge for pedologists is to provide reliable information in innovative and proactive ways.

Smith, C. A. S., Webb, K. T., Kenney, E., Anderson, A. and Kroetsch, D. 2011. Brunisolic soils of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 695-717. Brunisols are considered as moderately developed soils formed under forest cover. They have a wide range of physical and chemical properties and no single dominant pedogenic process drives the development of these soils. Brunisols are some of the more common soils in Canada, occupying over 1.2 million km² of land, roughly equivalent to the area of Podzolic soils, and about half the area of the most common soil order in Canada, the Cryosols. Brunisols occur mainly within the boreal forest regions, but extend across the country with the exception of the Arctic and prairie regions. Within the zone of discontinuous permafrost they co-exist on landscapes with Cryosols. In humid regions of both eastern and western Canada they form a continuum of soil development with Podzolic soils. Within subhumid to semi-arid regions they often co-exist with Luvisolic soils, occurring on parent materials too coarse to enable Luvisolic soil formation. Brunisols equate closely to the Cambisol reference group in the World Reference Base taxonomic system and to several suborders of the Inceptisol order in Soil Taxonomy. Both Melanic and Sombric Brunisols are important agricultural soils in British Columbia, Ontario and the Maritime provinces. Eutric and Dystric Brunisols support commercial forest stands throughout the boreal forest and western cordillera of Canada.

Pennock, D., Bedard-Haughn, A. and Viaud, V. 2011. Chernozemic soils of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 719-747. Chernozemic soils in Canada have a characteristic biomantle that fully expresses the effect of organisms on soil formation. Additions of large amounts of below-ground biomass from grasses are transformed into complex organic compounds through the activities of meso- and macro-fauna, microbial degradation and combustion by fires. Degradation is regulated by (a) climatic influences on plant inputs and microbial activity, (b) the chemical and biochemical nature of the residues, (c) encapsulation of organic matter within aggregates by soil micro-faunal activities and freeze-thaw processes and (d) protection against decomposition by Ca² and clay minerals. These organic compounds are mixed with the mineral matrix through the action of organisms from mites to badgers. Regional differences in the regulators cause differences in soil organic carbon (SOC) storage and the colour value of the surface Chernozemic A horizon. The storage of SOC is lowest in the Brown soil zone (∼60 to 80 Mg ha^-1) and greatest in the Black soil zone (∼120 to 150 Mg ha^-1); this corresponds to a decrease in the annual water deficit from ∼200 mm (Brown) to 70 to 100 mm (Black). Where soil CaCO₃ contents are high either through initial concentration in the parent material or by the precipitation of secondary CaCO₃, substantially higher SOC storage than the regional norms can result. A repetitive catenary pattern occurs throughout the region. The primary controls on this pattern are hydrological - a lateral component to water flow in hillslopes leads to more developed horizonation downslope, and discharge surrounding wetlands causes precipitation of secondary carbonate minerals and more soluble salts in a fringe surrounding the wetlands. Chernozemic landscapes have been highly altered by humans through their conversion to agricultural production. Loss of the dense root network of the native grasslands causes a substantial decrease in SOC. This loss of carbon and reduction in A horizon thickness is accelerated by erosion; the effects of tillage erosion are now recognized as being ubiquitous through the agricultural region. The substantial amounts of SOC storage and our ability to increase storage through altered management practices make these soils a particular focus of interest in a future made more uncertain by the possibility of human-induced climatic change.

Tarnocai, C. and Bockheim, J. G. 2011. Cryosolic soils of Canada: Genesis, distribution, and classification. Can. J. Soil. Sci. 91: 749-762. Cryosols are permafrost-affected soils whose genesis is dominated by cryogenic processes, resulting in unique macromorphologies, micromorphologies, thermal characteristics, and physical and chemical properties. In addition, these soils are carbon sinks, storing high amounts of organic carbon collected for thousands of years. In the Canadian soil classification, the Cryosolic Order includes mineral and organic soils that have both cryogenic properties and permafrost within 1 or 2 m of the soil surface. This soil order is divided into Turbic, Static and Organic great groups on the basis of the soil materials (mineral or organic), cryogenic properties and depth to permafrost. The great groups are subdivided into subgroups on the basis of soil development and the resulting diagnostic soil horizons. Cryosols are commonly associated with the presence of ground ice in the subsoil. This causes serious problems when areas containing these soils are used for agriculture and construction projects (such as roads, town sites and airstrips). Therefore, where Cryosols have high ice content, it is especially important either to avoid these activities or to use farming and construction methods that maintain the negative thermal balance.

Bedard-Haughn, A. 2011. Gleysolic soils of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 763-779. This review examines the pedogenesis of Gleysolic soils, including how they affect and are affected by land use and climate change. In the Canadian System of Soil Classification, the Gleysolic Order includes all those soils with morphologic features that provide dominant physical evidence of oxidation-reduction processes or gleying. Gley features include dull coloured soil matrices and/or brightly coloured mottles, which arise due to periodic or permanently saturated conditions. Under saturated conditions, oxygen is rapidly depleted and alternative terminal electron acceptors (such as iron, Fe³ ) are used by microorganisms in the decomposition of organic matter. Gleysolic soils are found throughout Canada, either in low-lying landscape positions in association with better-drained soil orders (e.g., Prairie Pothole region), or as the dominant soil type where topography and/or a slowly permeable substrate prolong the period of saturation (e.g., Clay Belt of northern Ontario and Quebec). These soils are often highly fertile agricultural land and are commonly drained for production, altering the soil-forming environment. Gleysolic soils have also been found to be potentially significant sources of greenhouse gas emissions due to high levels of denitrification and methanogenesis under their characteristic reducing conditions. Given their economic, ecologic, and environmental significance, further research is required to refine our understanding and classification of Gleysolic soils, particularly with respect to (1) how Gleysols are affected by human- or climate-change-induced changes to the drainage regime (either progressing towards reducing conditions or regressing to a non-redoximorphic state), (2) classification of carbonated and saline Gleysols, and (3) pseudogley versus groundwater Gleysols.

Lavkulich, L. M. and Arocena, J. M. 2011. Luvisols of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 781-806. Luvisols link the soil continuum on the Quaternary landscapes. These soils are developed from parent materials rich in Ca and Mg in a relatively humid climate. An acidic eluvial horizon overlying a phyllosilicate-enriched illuvial Bt horizon is the common horizon sequence in Luvisolic soils. Lessivage or the translocation of clays with minimal chemical alteration is the characteristic soil-forming process and results to the diagnostic Bt horizon with well-developed, oriented clay skins or cutans. These soils commonly form intergrades with Chernozems, Podzols and Vertisols. With time, the eluvial horizons experience increased chemical weathering and further release of sequioxides to form Brunisolic and Podzolic sequences within the eluvial Ae in biseqeual soils. Lessivage significantly influences several ecosystem functions of soils. The high amounts of phyllosilicates in the Bt horizon serve as one of the most active sorption sites in soils for metals and organic materials including soil carbon. Sorption of cations takes place through cation exchange reactions and determines the availability of cations to plant roots as well as in the “colloid facilitated transport” of strongly sorbing metals and organic pollutants. Clays in Bt can be restrictive to water and air movement as well as to root growth and distribution. Agricultural and forestry practices such as tillage can compact the structure of Luvisols and may decrease soil productivity.

Kroetsch, D. J., Geng, X., Chang, S. X. and Saurette, D. D. 2011. Organic soils of Canada:Part 1. Wetland Organic soils. Can. J. Soil Sci. 91: 807-822. In the Canadian System of Soil Classification, the Organic order represents those soils that have developed from materials that are comprised primarily of plant tissue remains and includes both wetland Organic soils and upland Organic soils. This review focuses on the first group; the latter group is discussed in Fox and Tarnocai (2011). Wetland Organic soils can be subdivided into three great groups: Fibrisol, Mesisol, and Humisol, reflecting the degree of decomposition of organic material and the vertical arrangement of different organic horizons and other horizons. Wetland Organic soils are present in all regions of Canada and are commonly referred to as (unfrozen) peatland soils. Unfrozen peatlands with Organic soils cover approximately 75 5568 km² (8.4%) of the land area of Canada. The two primary processes of formation of wetland Organic soils are paludification and terrestrialization. The major taxonomic issues identified for the wetland Organic soils concerns the lack of taxonomic protocols for limnic materials within the soil control section. This is an issue for those soil profiles in which the middle tier is dominated by, if not entirely composed of, deposited limnic materials. Further work is required to determine if these issues should be expressed at the great group or subgroup level of classification. Our understanding of the effects of management practices such as cultivation, tree removal, drainage, and peat extraction on soil properties needs to be translated into models of soil development.

Fox, C. A. and Tarnocai, C. 2011. Organic soils of Canada: Part 2. Upland Organic soils. Can. J. Soil Sci. 91: 823-842. Soils from upland moderately well-drained environments with thick accumulations (>10 cm over lithic contact; >40 cm over mineral soil) of folic materials (forest materials, branches, roots, and other non-wetland materials) are classified within the Folisol great group in the Organic Order since the 1987 revision of the Canadian System of Soil Classification. The Folisol great group correlates to Folist in Keys to Soil Taxonomy and Folic Histosol in World Reference Base for Soil Resources (FAO). Two subgroups - Hemic and Humic Folisol - account for most Folisols addressing the state of decomposition of folic materials. The Lignic and Histic Folisol subgroups identify specific kinds of folic accumulations. Folisolic soils can occur throughout Canada, in forest, heath, and alpine ecosytems with cool, moist, humid environments, but are most prominent within the Pacific Maritime Ecozone; areal extent in Canada is ~12 505 km². The main genetic process is the accumulation and decomposition of the folic materials that lead to distinct F and H horizons. Recommendations for research needs are presented to address outstanding taxonomic questions for: 1. Classification of Folisols as a separate soil order; and 2. Taxonomic protocols for lowercase suffixes for the L, F and H horizons and the need for enhanced humus form classifications. Some of the historical proposals to address these issues are discussed. Folisols should be considered extremely sensitive environmentally because of their markedly different genetic development being dependent on thick accumulations of folic materials, their limited and unique distribution in Canada, and their importance for forest sustainability.

Sanborn, P., Lamontagne, L. and Hendershot, W. 2011. Podzolic soils of Canada : Genesis, distribution, and classification. Can. J. Soil Sci. 91: 843-880. Podzolic soils occupy 14.3% of the Canadian landmass, and occur in two widely separated areas, eastern Canada (northern Ontario, Quebec, Maritimes) and British Columbia, usually under coniferous forest and on non-calcareous parent materials. Broad climatic control of Podzol distribution and properties is evident at the national scale, with higher organic matter concentrations (Ferro-Humic Podzols) in wetter climates, in contrast to Humo-Ferric Podzols predominating in drier boreal forest regions. Humic Podzols are least abundant and are restricted to the wettest landscape positions. International and Canadian research suggests that a more diverse range of processes is involved in podzolization than was envisioned in the 1960s, and proposed mechanisms must account for observed patterns of organic matter distribution and a diverse array of inorganic amorphous constituents in profiles. Taxonomic concepts of Podzolic soils in the Canadian System of Soil Classification have remained consistent since the late 1970s, and the higher-level criteria defining the order and its great groups have proved to be meaningful in new applications, such as delineating soil carbon stocks across Canadian landscapes. Canadian contributions to pedological research on Podzols declined dramatically after 1990, coincident with shifting research priorities in soil science and diminished activity in soil survey.

VandenBygaart, A. J. 2011. Regosolic soils of Canada: Genesis, distribution and classification. Can. J. Soil Sci. 91: 881-887. Regosolic soils of the Canadian System of Soil Classification are those soils that are weakly developed and do not contain a recognizable B horizon at least 5 cm thick. They must be able to support plant life and thus represent the boundary between pedologic and geologic realms. They commonly occur in Canada where recent geomorphic or anthropogenic processes have exposed fresh parent materials to the climatic forcings at the earth's surface, but can also occur where parent materials are highly resistant to weathering or where climatic conditions are arid and cold. A key stage in their development involves stabilization of the parent material usually by vegetation, which through the plant carbon cycle provides organic matter to the surface, a key component of many soil formation processes. Regosolic soils occur broadly across Canada with major areas in southern Quebec, southern Manitoba, the Rocky Mountains and the Arctic. Classification and taxonomy are fairly straightforward in that all Regosolic soils lack a well-developed B horizon. They are divided into two Great Groups based on the development of an Ah horizon that is either greater than 10 cm thick or is less than 10 cm thick or absent.

Miller, J. J. and Brierley, J. A. 2011. Solonetzic soils of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 889-902. Soils of the Solonetzic order are defined as having a Solonetzic B horizon designated as a Bn or Bnt horizon. The Solonetzic Order includes four great groups: Solonetz, Solodized Solonetz, Solod, and Vertic Solonetz. Solonetzic soils are thought to develop via the stepwise pedogenic processes of salinization, solonization (desalinzation and alkalization), and solodization. Soluble salts are brought into the soil pedon of Solonetzic soils by capillary movement and evaporation from spring to fall, and upward water flow from the water table to the freezing zone in the winter deposits salts upon freezing. Solonization proceeds when desalinization lowers the total salt content and alkalization is initiated by high exchangeable Na. Solodization occurs when anisotropic flow conditions or a change in vertical hydraulic gradients prevent capillary rise and replenishment of soluble Na in the Bn horizon. Two common Solonetzic catenas are found in the prairies. In the first sequence, Gleyed Solonetz or Solonetz occur in the depressional areas of the landscape, and soils then grade through Solodized Solonetz, Solods, and in some cases, Chernozems or normal zonal soils at higher elevations. In the second sequence, Solods are found in the lowest topographic position, while Solodized Solonetz, Solonetz and Chernozems are found at progressively higher slope positions. Solonetzic soils have unique properties that adversely affect their use for agriculture and other land uses (e.g., construction, septic systems). Further interdisciplinary research is required to better understand the genesis of these soils at the “meter scale” or local landscape level because of the extreme spatial variability of these soils.

Brierley, J. A., Stonehouse, H. B. and Mermut, A. R. 2011. Vertisolic soils of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 903-916. The Vertisolic soil order is the most recent addition to the Canadian System of Soil Classification (1998). Soils of the Vertisolic order in Canada occur within the Brown, Dark Brown, and Black soil zones, associated with the Prairie ecozone. Due to the absence of swelling clays in central Canada, morphological characteristics of Vertisolic or vertic intergrades are not recognized in soils occurring to the east of Manitoba. Finetextured parent materials dominated by the presence of swelling silicate clays in conjunction with appropriate climatic factors are the principal soil-forming factors for these soils. Two Great Groups are recognized within the Vertisolic order: the Vertisol and Humic Vertisol. Soils of the Vertisol great group are associated with the arid portions of the Prairie ecozone, specifically the Mixed Grassland ecoregion, and Brown soil zone. Humic Vertisols occur within the Dark Brown and drier portions of the Black soil zone. Each Vertisolic soil great group contains three subgroups: Orthic, Gleyed and Gleysolic. Classification to this level is based upon the presence of mottles (reflecting the duration of soil saturation) within the upper 50 cm of the surface. Vertisolic soils develop in finetextured parent materials of high shrink-swell potential and pose problems for agricultural land use and engineering purposes.