论土种单元的划分

我国土壤基层分类的研究尚属薄弱环节.解放前,土壤基层分类采用美国的土系制;解放初期采用苏联的土种制和连续命名法;1958年全国第一次土壤普查中,改用农民习用的土壤名称,独立命名,一直沿用至今,而未对这些命名加以系统提炼和整理,对土壤基层分类缺乏明确的原则和标准.     

Humus Horizons of Soils in Urban Ecosystems

The origin, structure, composition, and properties of soil humus horizons in functional zones of St. Petersburg have been studied. The radiocarbon age of organic matter in the humus horizons varies from 500 to 2700 years, which attests to the natural origin of humus. The structure of microbiomes in the humus horizons of soils under different plant communities has its specific features. The taxonomic structure of microbial communities at the phylum level reflects both genetic features of natural soils and the impact of anthropogenic factors, including alkalization typical of the studied urban soils. Tomographic studies have shown that the transporting system of humus horizons is less developed in the anthropogenically transformed soils in comparison with the natural soils. It can be supposed that the intensity of water and gas exchange in the anthropogenic soils is much lower than that in the natural soils. The fractional and group composition of humus in the urban soils is specified by the long-term pedogenesis, on one hand, and by the impact of metabolic products of the city and the factors of soil formation in the megalopolis, on the other hand. Bulk density of the humus horizon in the urban soils is higher than that in the natural soils; the portion of overcompacted humus horizons in the urban soils reaches 44%. Humus horizons of the lawns along highways are most contaminated with heavy metals: Pb, Zn, and Cu. There are no definite regularities in the distribution of major nutrients (NPK) in the humus horizons of anthropogenic soils.     

Inclusion of soils and soil-like bodies of urban territories into the Russian soil classification system

The results of the Internet discussion on the classification of urban soils aimed at evaluating their possible inclusion into the modern Russian soil classification system adopted by a wide range of specialists are presented. The first step was to address the urban diagnostic horizons as the basis for identifying soil types according to the rules of the Russian soil classification. New diagnostic horizons were proposed for urban soils: urbic (UR), filled compost-mineral (RAT), and filled peat (RT). The combination of these horizons with other diagnostic horizons and layers of technogenic materials correspond to different soil types. At the subtype level, the diagnostic properties (qualifiers) that may reflect both natural phenomena (gley, alkalinity) and technogenic impacts on the soils (urbistratified; phosphatic; or poorly expressed urban—ur, rat, rt) are used. Some corrections were proposed for the system of parent materials in urban environments. Urban soils formerly described in another nomenclature—urbanozems, urbiquasizems, and culturozems—are correlated with the taxa in all the trunks of the system. The proposals accepted can be used for the next updated version of the new Russian soil classification system.     

Diagnostic horizons in the Russian soil classification system

The analysis of the responses of users of the substantive-genetic Russian soil classification system revealed some problems concerning the genetic (diagnostic) horizons. Applying horizons is essential since soil diagnostics are based on their identification and their combinations in soil profiles. In the recent Russian system, there are many diagnostic horizons, and their recognition is not always easy. This review is aimed at displaying the main elements and the genetic essence of the horizons, as well as the reasons to choose the diagnostic criteria and parameters for most of them. The horizons are grouped into genetic sets, and the specific properties of the horizons are emphasized, as well as the differences between the horizons and the feasibility to introduce new horizons. A rough comparison of the diagnostic horizons in the Russian and WRB systems revealed the considerable similarity of the taxa, whose definitions depend on the presence of the diagnostic horizons: these are the orders and soil reference groups, respectively.     

Soil system and pedogenic processes: Self-organization, time scales, and environmental significance

The essence of pedogenesis, as a synergetic process, consists in generation, selection, accumulation and differentiation of the solids produced in the course of bio-abiotic processes functioning within a soil body. Soil formation in the broad sense is the result of synergetic processes of self-organization of an in situ soil system during its functioning in time and space. Soil formation, sensu stricto, is the transformation of the solid-phase lithomatrix (parent material) of the soil system into the pedomatrix (soil body, soil mantle). Pedogenesis is perceived as an integration of specific pedogenic processes (SPP); each of them characterized by a definite set of solid-phase pedogenic features. Each soil body is formed by a combination of some SPP. The whole set of SPP may be grouped in accordance with their essence, characteristic times (rates) and reversibility-irreversibility. In terms of characteristic times (rates) they may be arranged in three main groups: rapid (10^1–2 years), medium-rate (10^3–4 years), and slow (10^5–6 years). Soil system functioning and soil formation are intimately linked but fundamentally different processes: the former is infinite in time, if not interrupted by external factors; the latter, as any self-organization process, is finite in time and tends to reach a steady state. The theoretical grouping of the pedogenic processes according to their essence and self-termination or quasi-equilibrium is proposed. All the diagnostic soil horizons (as defined in WRB) are perceived as more or less stable and “mature” degrees of soil self-development. They may be separated into favorable and unfavorable with respect to their suitability for biota. Favorable conditions are generally common in 12 out of 39 diagnostic horizons and properties (32%). They are mainly influenced by biotic fluxes and cycles, which are comparable to, or exceed, abiotic fluxes and cycles in their strength and capacity. In this case, biota transforms and improves the environment rather than adapts to it. Unfavorable conditions are more common in 27 out of 39 diagnostic horizons and properties (68%). They are influenced by the mutual action both of biotic and abiotic fluxes and cycles. In this case, biota adapts to the environment rather than improves it.     

Soil system and pedogenic processes: Self-organization,time scales,and environmental significance

The essence of pedogenesis, as a synergetic process, consists in generation, selection, accumulation and differentiation of the solids produced in the course of bio-abiotic processes functioning within a soil body. Soil formation in the broad sense is the result of synergetic processes of self-organization of an in situ soil system during its functioning in time and space. Soil formation, sensu stricto, is the transformation of the solid-phase lithomatrix (parent material) of the soil system into the pedomatrix (soil body, soil mantle). Pedogenesis is perceived as an integration of specific pedogenic processes (SPP); each of them characterized by a definite set of solid-phase pedogenic features. Each soil body is formed by a combination of some SPP. The whole set of SPP may be grouped in accordance with their essence, characteristic times (rates) and reversibility-irreversibility. In terms of characteristic times (rates) they may be arranged in three main groups: rapid (10^1–2 years), medium-rate (10^3–4 years), and slow (10^5–6 years). Soil system functioning and soil formation are intimately linked but fundamentally different processes: the former is infinite in time, if not interrupted by external factors; the latter, as any self-organization process, is finite in time and tends to reach a steady state. The theoretical grouping of the pedogenic processes according to their essence and self-termination or quasi-equilibrium is proposed. All the diagnostic soil horizons (as defined in WRB) are perceived as more or less stable and “mature” degrees of soil self-development. They may be separated into favorable and unfavorable with respect to their suitability for biota. Favorable conditions are generally common in 12 out of 39 diagnostic horizons and properties (32%). They are mainly influenced by biotic fluxes and cycles, which are comparable to, or exceed, abiotic fluxes and cycles in their strength and capacity. In this case, biota transforms and improves the environment rather than adapts to it. Unfavorable conditions are more common in 27 out of 39 diagnostic horizons and properties (68%). They are influenced by the mutual action both of biotic and abiotic fluxes and cycles. In this case, biota adapts to the environment rather than improves it.     

栾城县土系划分及其基本性状

本文根据中国土壤系统分类的原则要求,对河北省栾城县土壤进行了全面调查,确立了特征土层,具体划分出16个土系,初步明确了其基本属性与区域分布。     

Characteristics of the induration of tephra-derived soils in Kyushu,Japan

The physical, chemical, and mineralogical properties as well as the micromorphology of five indurated volcanic ash soils in Kyushu, Japan were investigated. The indurated soils were divided into two types based on the physical and chemical properties. Type 1 was not indurated in its moist state, but shrank and became very hard by air-drying. Type 1 included the buried volcanic ash soils whose physical and chemical properties were similar to those of other buried volcanic ash soils except for the property of induration by air-drying. The mechanism of the induration is still unknown, although it is considered to have occurred during the long period after the deposition of tephra under the influence of soil formation processes. Type 2 included the tephra layers that were indurated in both moist and air-dried states. The carbon and clay contents of type 2 were remarkably lower than those of type 1. Type 2 had not been affected by the soil formation process but had undergone induration soon after the deposition of the tephra. Neither type 1 nor type 2 could be classified into any indurated horizons that are defined in the present soil classification system. For the improvement of soil productivity, type 1 should be harrowed thoroughly soon after its exposure to the surface, and type 2 should be harrowed or removed using farm machinery.     

Technosols in the World Reference Base for Soil Resources – history and definitions

ABSTRACT

The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the update 2015 of its third edition. WRB has two levels: first and second. The first level comprises 32 Reference Soil Groups (RSGs), identified using a Key. At the second level, the soil names are constructed by adding a set of qualifiers to the name of the RSG. In the WRB, diagnostic horizons, properties and materials are defined. Diagnostic materials are materials that significantly influence soil-forming processes. Diagnostic properties and horizons have a combination of attributes that mostly reflect results of soil-forming processes.

The RSG Technosols was introduced in the second edition of the WRB in 2006. In the current version of the WRB, two diagnostic materials are defined for Technosols: artefacts and technic hard material. Artefacts are substances that are created or substantially modified by humans or brought to the surface from a depth, where they were not influenced by surface processes. The technic hard material is a (relatively) continuous consolidated material resulting from an industrial process. The Technosols are at the third place in the Key after Histosols and Anthrosols. A soil is a Technosol if it has technic hard material within 5 cm or a geomembrane or a significant amount of artefacts within 100 cm. If a soil has no technic hard material and no geomembrane but a layer with artefacts that has undergone enough soil formation to develop a diagnostic horizon typical for advanced pedogenesis, the soil is excluded from the Technosols. There are specific qualifiers to further characterise the Technosols. They are also important to characterise soils other than Technosols that have artefacts or technic hard material. Human-transported natural soil material does not qualify as Technosol.     

The effect of petrocalcic horizons on the content and distribution of organic carbon in a Mediterranean semiarid landscape

Petrocalcic horizons are frequent in soils of semiarid landscapes. A survey of SIC and SOC contents made in Southern Spain in a pilot area with well defined geomorphological surfaces showed that topsoils overlying petrocalcic horizons are almost twice as rich in SOC as soil of similar depth without petrocalcic horizons. This could be due to impedance to root penetration, changes in redox potential and soil water availability caused by the presence of indurated crust. Soil age, on the contrary, seems not be an essential factor, since only a short time is required to reach a steady state in SOC in comparison to the time span available for soil formation on the different geomorphic surfaces.     

Ecological niches of major soil types in Russia: Geographical aspects of the new Russian soil classification system

The factors of soil formation are not directly taken into account in the new profile-genetic Russian soil classification system; they are not reflected in the names and diagnostics of the soils. At the same time, as well as in many other modern soil classification systems, including the American Soil Taxonomy and the WRB system, the choice of the diagnostic criteria, the establishment of the relationships between them, and the setting of the quantitative boundaries between the soil taxa are based on our perception of soil geneses with due account for the factors of soil formation. In contrast to the ecological-genetic soil classification system of 1977, information on the factors of soil formation in the new system is encoded in the properties of the soil horizons. In some cases, this is insufficient for the definite geographic localization of soils and complicates the practical application of the new classification system. In this context, information on the ecological niches of soil types was included in the field manual on soil correlation-an abridged version of the soil classification system published in 2008—in the form of special tables developed for native and agrogenic soils. The analysis of these tables made it possible to outline certain geographic regularities in the distribution of soil types belonging to the trunk of postlithogenic soils.     

Higher levels of description—approaches to the micromorphological characterisation of Russian soils

Several attempts were made in the past to identify high-level soil microfabrics, following the ideas of Kubiëna. They resulted in proposals to identify specific fabric types, soil materials, somas, formations, or morphotypes, based on the combinations of micromorphological characteristics of the studied horizons of soils. These units present complex (integrated, typical, and central) micromorphological images of soil horizons or materials. Using the available information on Russian soils, the author defined the “micromorphotypes” of soil horizons by illustrating this approach by two examples of simple and complicated genetic horizons. Emphasis was put on genetic and diagnostic aspects of micromorphological interpretations, which is traditional for Russian micromorphological studies. Moreover, the definition of “micromorphotypes” was derived from the ideas of diagnostic horizons, which serve as a base for the new Russian soil classification system. Examples of “micromorphotypes” are discussed for a Chernozem and major mineral horizons of loamy soils with textural profile (correlated with Albeluvisols in the WRB system). They illustrate the morphogenetic principles applied, and also bring to light some problems concerning the choice and hierarchy of criteria used for a number of soils.This “micromorphotypes” approach may contribute to the diagnostics of horizons for soil classification, for detection of human impacts, and for the identification of paleosols and their diagenetic changes. To facilitate contacts with nonprofessionals in micromorphology, a simple terminology and a priority of pedogenic principles seem to be preferable.     

An assessment of anthropogenic soil transformation of the arkhangelskoe museum estate based on the example of studying inclusions

The natural soil cover of a territory is transformed during the formation of landscape architecture objects. Natural soils are replaced by anthropogenically transformed soils and soil-like bodies. Due to technological features, either only surface horizons of natural soils or an entire range of horizons within a significant profile can be replaced. To determine the extent of transformation, the composition of inclusions of anthropogenically transformed and anthropogenic soils of the museum-estate Arkhangelskoe was studied. The study results were used to assess the extent of soil contamination and to determine the features of the composition of anthropogenic inclusions. A practical proposal on research on the coarse fraction inclusions of the soil was made.     

The effects of agrogenic transformation on soil profile morphology,organic carbon and physico-chemical properties in Retisols of Western Lithuania

The aim of this study was to determine changes in the morphological, physical and chemical properties of Retisols caused by their agrogenic transformation. The study carried out on Retisols on relatively natural and agrogenically affected land in 2016. Soil samples taken from the genetic horizons of all profiles to measure soil organic carbon, pH, hydromorphic and physical properties. Due to long-term, deep ploughing, the sequence of soil horizons in the Retisol profile had changed from O–Ah–El–ElBt to Ahp–ElBt. Intensive soil liming changed chemical properties and morphological features of Retisol. The clay and silt particles leached out of from the Ah and El horizons to the deeper layers due to illuviation and podsolization. The content of SOC in the 0–30 cm layer of the Ah horizon of agrogenically affected Retisol was 1.0%, and in the forest Retisol – 1.7%; however, forest Retisol was more acidic. Ploughing and no tillage management caused a reduction in total porosity, water holding capacity and plant available water content compared with the other land-uses. We conclude that the use of ploughless tillage on Retisol is not identical to the conditions of natural soil formation and soil fertility maintenance.     

SOIL CLASSIFICATION IN THE SOIL SURVEY OF ENGLAND AND WALES

The development of soil classification as a basis for soil mapping in England and Wales is briefly reviewed, and a system for future use is described. The things classified are soil profiles, and classes are defined by relatively permanent characteristics that can be observed or measured in the field, or inferred within limits from field examination by comparison with analysed samples. Profile classes are defined at four categorical levels by progressive division, and are termed major groups, groups, subgroups, and soil series respectively. Classes in the three higher categories are defined partly by the composition of the soil material and partly by the presence or absence of particular diagnostic horizons, or evidence of recent alluvial origin, within specified depths. Soil series are distinguished by other characteristics, chiefly lithologic, not differentiating in higher categories. Most of the soil groups, regarded as the principal category above the soil series, are closely paralleled in other European systems, in the U.S.D.A. system (7th Approximation with subsequent amendments), or in both. Compared with the system used hitherto, the main innovations are the use of specific soil properties to define classes at all categorical levels, and the separation at group level of classes based primarily on inherited lithologic characteristics. The soil-profile classification provides a uniform basis for identifying soil map units, considered as classes of delineated soil bodies. When a map unit is identified by the name of a profile class, it is implied that most of the soil in each delineation conforms to that class, and that unconforming inclusions belong to one or more closely related classes or occupy an insignificant proportionate area. Map units identified by land attributes not differentiating in the profile classification are termed phases.     

Classification schemes for the acidity,base saturation,and acidification status of forest soils in Switzerland

Soil chemical parameters related to soil acidity were determined for 1450 soil samples taken from individual mineral soil horizons in 257 forest soils in Switzerland, 196 developed from carbonate‐containing and 61 from carbonate‐free parent material. The distribution of pH values and exchangeable base cations in corresponding pH ranges were related to the capacity and rate of buffer reactions in the soil. Based on this, five acidity classes for individual soil samples were defined. To describe and classify the status of soil acidity and base saturation (BS) of an entire soil body, the pH and the BS of the total fine earth in the soil were calculated from the pH and BS, respectively, of the individual soil horizons and the estimated volumetric content of fine earth. The status of soil acidification of soil profiles was assessed primarily using the total amount of exchangeable acidic cations in percent of the CEC of the fine earth in the entire soil profile. As a second factor, the gradient between the acidity class of the most acidic soil horizon and the estimated acidity class at the beginning of soil formation was used. The application of these classification schemes to our collection of soil profiles revealed the great influence played by the type of parent material. The acidification status of most soils on carbonate‐containing parent material was classified as very weak to weak, whereas soils on carbonate‐free parent material were found to be strongly to very strongly acidified. In terms of parent rock material, microclimate, and natural vegetation, the results of this study and the proposed classification schemes can be considered appropriate for large parts of Europe.     

Influence of afforestation on soil genesis,morphology and properties in glacial till deposits

A study of soil morphological, physical and chemical properties was performed in woodland of different ages, in which spruce (Picea abies), aspen (Populus tremula) and birch (Betula pendula) growing stocks have colonized former agricultural land. The aim of the study was to clarify changes in soil genesis, morphology and properties due to the afforestation of abandoned agricultural land in glacial till deposits. The research showed that soil in these deposits (loamy sand, loam, clay) retains the morphological properties of agricultural land for up to 100 years. Secondary podzolization features in the soil profiles were observed within 100 years of the start of afforestation, whereas the diagnostic properties of Albic and Spodic horizons had not developed in the soil profile after 200 years. This study demonstrated that the morphological and physico-chemical properties of forest litter horizons, including the accumulation of organic substances, are dependent on forest age; however, changes in the properties of mineral soil horizons are mainly related to woodland age. Following the afforestation of agricultural lands, changes in soil pH_KCl, organic matter content and extractable Al and Fe concentrations occur more rapidly than changes in soil diagnostic properties and profile formation.     

A BASIS FOR THE CLASSIFICATION OF SOIL

Considering the nature of soil and the ends which a classification must serve, principles are stated whereby a soil classification may be devised for application over extensive areas of varied soil composition. Naturally occurring bodies of soil, each with a high degree of homogeneity, are apparent rather than real individuals as their properties overlap to form a continuum. This continuum is multi-dimensional because soil is characterized by numerous properties. The procedure of devising a classification is one of subdividing the continuum such that class boundaries accommodate, as far as possible, apparent individuals rather than of grouping like apparent individuals together. A classification may be used to locate the position of a profile in the continuum and so define its relationship with other profiles. It may also be used to indicate the soil composition of land by using soil classes on a map to show differences in the soil mantle. The latter procedure may best be regarded as land classification or soil mapping rather than soil classification; a class of land or mapped area seldom contains profiles belonging exclusively to a single class, whereas a soil class never contains profiles of another class. The soil form, a specific arrangement of diagnostic horizons, is introduced as a category above the series to facilitate the identification of soil profiles. Member series of a form are defined according to property variations within the diagnostic horizons of the form. It is suggested that a binomial system of profile nomenclature, using the form and the series, would have much to commend it.