Advances in pedology in Japan since the late 19th century: soil surveys and classification systems

The characteristics of Japanese soil were developed by wide paddy field farming, the influence of volcanic ash on soil, and a perudic moisture regime under temperate climatic conditions. Major soil classifications in Japan have developed in line with public work projects and soils in Japan have tended to be classified independently depending on the land use, such as cultivated area, forest, and so forth. Consequently, there is no available soil map drawn with a single framework of soil classification on a practical map scale, which hampers the progress of environmental studies such as watershed-level nutrient cycling, carbon sequestration and so on. In response, we published the Comprehensive Soil Classification System of Japan – First Approximation; a more practical system that enables the nationwide classification of soils. In it, we defined the following categories: soil great group, soil group, soil subgroup, and soil series group, determined by dichotomous keys. The proposed system contains 27 soil groups, 116 soil subgroups and 381 soil series groups. Setting these 4 category levels renders the system usable for both general outlines and detailed descriptions, and to create soil maps and soil information on various scales. Discipline: Soils, fertilizers and plant nutrition Additional key words: Ando soils, Paddy soils, Upland soils *Corresponding author: e-mail obara@affrc.go.jp Received 12 December 2013; accepted 10 November 2014. Introduction Soil is a natural body that covers the thin surface layer of the Earth. It provides nutrients and water to plants and supports plant bodies. Soil is also a living space and habitat for animals and microorganisms. Although soils have common general properties, their figure and properties vary considerably depending on the soil forming factors. Soils are the end product of the collective influence of climate, relief, organisms, parent materials and time. Understanding soil varieties and classifying them while keeping their different characteristics in mind is crucial to recognizing the environment, managing soils and keeping land sustainable. In Japan, these differences in soils were recognized and old documents of agricultural guidance from the Edo era (1600 – 1868) have emerged. More recently, the first national soil survey program was launched in the 1870s, using a European agro-geological soil classification introduced by Dr. Fesca from Germany, following which certain soil survey programs have been carried out for agricultural land, forest land, and other land use to date. Soil classification systems were also developed to order data and publish survey reports, referring to the development of soil classification systems overseas and international organizations such as FAO and IUSS. The characteristics of Japanese soil emerged through wide paddy field farming, the influence of volcanic ash on soil, and a perudic moisture regime under temperate climatic conditions. The soil classifications of Japan were developed to identify soils with peculiar characteristics under those conditions, and group soils in meaningful ways for agricultural, and forestry production. In this paper, we would like to introduce soil classification of major soils in Japan and provide an outline of the latest soil classification; namely “the Comprehensive Soil Classification System of Japan – First Approximation”. 1. General view of the soil classification of major soils in Japan The soil classification in Japan has proactively developed in three fields, namely paddy soils, volcanic ash soils,

Several pedological soil classification schemes have been developed to classify soils worldwide based on morphological features, stage of weathering, and to some extent their chemical and physical properties. Three soil classification systems are commonly used as research and teaching tools in the tropics, namely, the USDA Soil Taxonomy classification, the FAO/UNESCO World Soil Legends, and the French soil classification system. Brazil, the country with the largest land area in the tropics, has its own national soil classification system. However, soil survey, classification, and interpretation are costly and time-consuming, and few countries in the tropics have completed soil maps that are at a scale detailed enough to be useful to farmers and land users. In the absence of soil information at state, county or farm level, the authors propose a simple descriptive grouping of major soils in the tropics based on clay mineralogy to facilitate discussion on soil management and plant production in the subsequent chapters of this book. Reference to the Soil Taxonomy classification will be made when such information is available. It should be pointed out that the main purpose of this technical grouping is to provide field workers, especially those who are less familiar with the various soil classification systems, with a simple framework for planning soil management strategies. It by no means replaces the national and international soil taxonomy and classification systems that are designed for communication among soil scientists and for more detailed interpretation of soil survey data and land-use planning. This technical scheme classifies major arable soils in the tropics into four groupings according to their dominant clay mineralogy. They are • kaolinitic soils • oxidic soils • allophanic soils • smectitic soils Kaolinitic soils are deeply weathered soils with a sand, loamy sand, or sandy loam texture in the surface horizon and a clayey B horizon (20-60%). Silt content is low (< 20%) throughout the profile. Kaolinite (> 90%) is the dominant mineral in the clay fraction. These soils have an effective CEC of less than 12 cmol/kg of clay in the lower B horizon. Kaolinitic soils have a relatively high bulk density, especially in the clayey subsoil horizons (> 1.40 Mg/m3). The structure of the subsoil horizons is usually massive or blocky.

Endorsement of USDA Soil Taxonomy by the International Union of Soil Sciences

Differences between local systems of soil classification hinder the communication between pedologists from different countries. The FAO–UNESCO Soil Map of the World, as a fruit of world-wide collaboration between innumerable soil scientists, is recognised internationally. Ideally, pedologists should be able to match whole classes in their local systems to those in an international soil classification system. The Australian Soil Classification (ASC) system, created specifically for Australian soil, is widely used in Australia, and Australian pedologists wish to translate the orders they recognise into the FAO soil units when writing for readers elsewhere. We explored the feasibility of matching soil orders in the ASC to units in the FAO legend using a multivariate analysis. Twenty soil properties, variates, of 4927 profiles were estimated from their visible–near infrared reflectance (vis–NIR) spectra. We arranged the profiles in a Euclidean 20-dimensional orthogonal vector space defined by standardised variates. Class centroids were computed in that space, and the Euclidean distances between the centroids of the ASC orders and units in the FAO scheme were also computed. The shortest distance between a centroid of any ASC order and one of units in the FAO classification was treated as a best match. With only one exception the best matches were those that an experienced pedologist might expect. Second and third nearest neighbours in the vector space provided additional insight. We conclude that vis–NIR spectra represent sufficiently well the essential characters of the soil and so spectra could form the basis for the development of a universal soil classification system. In our case, we could assign with confidence the orders of the ASC to the units of the FAO scheme. A similar approach could be applied to link other national classification systems to one or other international systems of soil classification.

In 2017, the Japanese Society of Pedology (the Fifth Committee for Soil Classification and Nomenclature) established the Japanese soil classification system. In the classification system, all the soils derived from volcanic ejecta (volcanic ash, pumice, scoria, etc.) are classified into the Great Group of Andosols, excluding Man-made and Organic soils, although some volcanic soils were classified into other soil groups, such as the Podozols and Brown forest soils in the previous classification systems. The aim of the present study was to verify and propose revision for the new system based on physicochemical data collected from forest soils across the Japan archipelago. Approximately 20% of the forest soils have andic properties and were classified into the Andosols in the Soil Classification System of Japan, which is consistent with the Andisols in Soil taxonomy and Andosols in World Reference Base for Soil Resources, excluding a few soils with low andic horizon thickness. Many other forest soils that were not classified into Andosols possessed some of the regosolic andic properties, and it was challenging to classify them into Regosolic Andosols or Brown forest soils. Therefore, additional diagnostic activities on the volcanic ejecta and glass are required to classify such soils appropriately. In the new classification system, the Fulvic Andosols soil group was abolished and substituted with the Humic and Brown-humic subgroups under the Non-allophanic and Allophanic Andosols, respectively. The revision was consistent with the traditional forest soil classification system. In conclusion, the classification of volcanic soils in the Soil Classification System of Japan was verified using forest soil data in Japan. Abbreviations CFSJ: Classification of Forest Soils in Japan (1975); CSCSJ: Comprehensive Soil Classification System of Japan, 1st approximation (2011); SCSJ: Soil Classification System of Japan (2017); ST: Keys to Soil taxonomy, Twelfth Edition (2014); USCSJ: Unified Soil Classification System of Japan, 2nd Approximation (2002); WRB: World Reference Base for Soil Resources (2014, 2015 updated)

The total area of irrigated rice fields on the slopes of Mount Argopura is 21,420.02 hectares. Soil that experiences flooding will change the characteristics of the physical, chemical, and soil classification properties. The aim of the study was to examine the soil characteristics and classification system of paddy fields on the slopes of Mount Argpura. The research was conducted in July–September 2022 in paddy fields on the slopes of Mount Raung. Soil analysis in the laboratory of the Faculty of Agriculture, University of Jember This research uses a descriptive exploratory method through field surveys. Parameter research on the chemical-physical characteristics of soil and soil classification The research shows that the average rainfall of paddy fields at the foot of Mount Argopura is 2,275 mm per year with a standard deviation of 514 mm and a coefficient of variance of 23%. The morphological horizons of the genesis results in paddy fields are generally Apg, Adg, Bwg, and Cg. The USDA's classification of soil Hydraquentic Humaquepts (pedon 1), Typic Epiaquepts (pedon 2), Aeric Epiaquepts (pedon 3), Indonesian soil classification Gleisol molik (pedon 1), Gleisol eutric (pedon 2), and Gleisol eutric (pedon 3), according to WRB/FAO Molic epireductic Gleisol (Aphihumic) (pedon 1), ochric reductive gleysol (ochric, clayic) (pedon 2), and ochric siltic reductive gleysol (pedon 3). Keywords: Mount Argopura, Rice fields, Tillage, Volcanics

The geotechnical properties of soils are often influenced by chemical compounds and mineral additives. This study investigates the effects of varying calcium chloride (CaCl2) contents (0% to 6% by weight of dry soil) on the Atterberg limits and classification of Marley soil (MS), stabilized with 8% lime (L), 20% natural pozzolana (NP), and their combination (8%L+20%NP). The research also examines the impact of curing time (1 and 30 days) on the plasticity index (PI) and soil classification, both with and without CaCl2. In the absence of CaCl2, the addition of L, alone or combined with NP, significantly reduced the PI of stabilized MS and markedly improved its classification, particularly with the L-NP combination over longer curing periods. In contrast, NP alone caused only a slight decrease in the PI. The inclusion of CaCl2 further reduced the PI in the MS‒L and MS‒L-NP mixtures. Notably, the transformation in soil classification was more substantial with L and L-NP than with NP alone. A comparative evaluation of the Unified Soil Classification System (USCS) and the British Soil Classification System (BSCS) revealed that the BSCS offered greater precision in classifying stabilized MS, underscoring its suitability for such applications. These findings highlight the significant benefits of incorporating CaCl2, alone or in combination with L or L-NP, in enhancing the PI and the classification of MS. The improvements in both PI and classification are influenced by several factors, including additive type and amount, CaCl₂ content, curing period, and the classification system employed. Keywords: Marley soil (MS), Mineral additives (L and NP), Calcium chloride (CaCl2), Atterberg limits, USCS and BSCS classification systems, Stabilization.

Underground gold mines in Nevada are exploiting increasingly deeper ore bodies comprised of weak to very weak rock masses. The Rock Mass Rating (RMR) classification system is widely used at underground gold mines in Nevada and is applicable in fair to good-quality rock masses, but is difficult to apply and loses reliability in very weak rock mass to soil-like material. Because very weak rock masses are transition materials that border engineering rock mass and soil classification systems, soil classification may sometimes be easier and more appropriate to provide insight into material behavior and properties. The Unified Soil Classification System (USCS) is the most likely choice for the classification of very weak rock mass to soil-like material because of its accepted use in tunnel engineering projects and its ability to predict soil-like material behavior underground. A correlation between the RMR and USCS systems was developed by comparing underground geotechnical RMR mapping to laboratory testing of bulk samples from the same locations, thereby assigning a numeric RMR value to the USCS classification that can be used in spreadsheet calculations and geostatistical analyses. The geotechnical classification system presented in this paper including a USCS–RMR correlation, RMR rating equations, and the Geo-Pick Strike Index is collectively introduced as the Weak Rock Mass Rating System (W-RMR). It is the authors’ hope that this system will aid in the classification of weak rock masses and more usable design tools based on the RMR system. More broadly, the RMR–USCS correlation and the W-RMR system help define the transition between engineering soil and rock mass classification systems and may provide insight for geotechnical design in very weak rock masses.

Classifying soils for a particular purpose involves the ordering of soils into groups with similar properties and for potential end uses. The classification of soil is a terrific conceptual and practical challenge, especially in arid environments. The challenge may spur on, or it may deter scientists or end users with an interest in soils. If a classification system proves to be relevant and user-friendly, it stimulates and encourages further work because it is recognised for its inherent capacity to create order and enhance the useful understanding and mapping of soils. General-purpose, internationally recognised soil classification systems such as Soil Taxonomy and the World Reference Base and other nationally recognised classification systems (e.g. Australian or South African) have proved to be tremendously useful for soil classification and advancing understanding of soils across the world. However, because the use of these general-purpose classifications requires considerable expertise and experience, there is a need for complementary special-purpose classification systems that are specifically tailored, for example, to particular environmental problems, land uses or local regions and that use plain language descriptions for soil types. General-purpose classification systems often lag in the incorporation of new terminologies, for example, classification of acid sulfate soils in the Murray-Darling Basin, Australia, has led to descriptions of soil types with subaqueous properties (submerged underwater), monosulfidic materials and hypersulfidic materials, to enable assessment of environmental risk and management options. In addition, new challenges face general-purpose soil classification systems, especially in response to the following questions most frequently asked by soil users: (1) what soil properties are changing vertically and laterally in landscapes and with time, especially in acid sulfate soils? and (2) what are the most suitable approaches for characterising, monitoring, predicting and managing soil changes for environmental impact assessments, pollution incidents, waste management, product development and technology support? The purpose of this chapter is to address these challenges by presenting new ideas and concepts on how best to predict and solve practical problems by focussing on the development of special-purpose or more technical soil classification systems, which use plain language names for soil types. To demonstrate the critical importance of developing special-purpose technical soil classifications, the following five case studies are presented, which tackle difficult problems involving highly complex issues: (1 and 2) soil and water degradation in large aquatic environments from the River Murray and Lower Lakes region in South Australia (changing climatic and anthropogenic modified environments) and from the Mesopotamian marshlands in Iraq (anthropogenic modified arid environment); (3) acid sulfate soil as a new geochemical sampling medium for mineral exploration; (4) soil damage to the Australian telecommunication optic fibre cable network from shrink-swell soils and soil corrosion; and (5) soil landscape features to assist police in locating buried objects in complex terrain.

As mentioned in Chap. 3, soils and their properties in Libya are influenced to the great extent by nature and conditions in which these soils were formed. Hence, the types of soil formed in Libya differ from one place to another, and this difference is related to the diversity in the factors responsible for soil formation. In this chapter, we discussed the most common Soil Classification Units found in the country and reviewed the main properties of the Libyan soils. As mentioned also in Chap. 2, Many soil studies have been carried out in Libya over the last four decades. These soil survey reports differ in their contents, types of maps, the scale of mapping, classification systems, methods of soil analysis, and the criteria on which the interpretation of data is based. The major soil classification systems used in Libya are the Russian soil classification system, the U.S.A Soil Taxonomy, and the FAO soil classification system. In the early 1990s, Libyan soil experts decided to adopt the U.S. A. Soil Taxonomy for future soil survey work and converted the names of soil taxonomic units from the Russian soil classification system to the U.S.A. one. The taxonomic units for the Libyan soils were discussed according to the Russian and U.S.A soil classification systems. According to the U.S.A. Soil Taxonomy, Soil Taxonomic Units of Libya are either Entisols or Aridisols. Alfisols, Mollisols, and Vertisols can only be found in Al Jabal Al Akhdar. Inceptisols are placed in both Al Jabal Al Akhdar and Jabal Nafusa. Soil Properties of the main soil taxonomic units at the great group levels were also discussed. The major soil limiting factors that are risking the agricultural activities in the country were also defined and will be discussed further in the next chapter.

Soil genesis, soil classification and soil survey

Cross-system legacy data applied to digital soil mapping: A case study of Second National Soil Survey data in China

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.

It is well known that most saline soils have salt accumulation at the soil surface and the root zone due to the capillary movement of saline groundwater and subsequent evaporation. The criteria for classifying soil as saline taxa are different in different soil classification systems. In Chinese Soil Taxonomy (CST), soils that have a salic horizon starting within 30 cm from the soil surface are named as Orthic Halosols. In the World Reference Base for the Soil Resources (WRB), soils that have a salic horizon starting within 50 cm from the soil surface are named as Solonchaks. In the US Soil Taxonomy (ST), soils that have a salic horizon starting within 100 cm from the soil surface are named as Salids. In China, a large area of saline soils was reclaimed for crop production. This chapter describes some soil profiles that were classified into saline taxa in CST, WRB, and ST before they are reclaimed, to see if these soils, after a long history of irrigation, are still classified into saline taxa in the three soil classification systems. The results showed that the salts were leached into certain depth, the salic horizons were observed at different depth from the surface, many profiles could not be classified as Orthic Halosols as identified earlier, some of them could not be classified as Solonchaks, and few of them even could not be classified as Salids. With a long irrigation history, the depth of salic horizon is related to the amount of irrigation water and irrigation models. When more water was used for irrigation each time, the salts were found at deeper layers. Relatively the surface irrigation leached the salts deeper than the drip irrigation. According to the present study, we suggest that the criteria of ST should be taken in order to keep the reclaimed saline soils in the saline taxa, i.e., soil classification should not be changed by irrigation. We also suggest that more soil survey should be taken for discovering how much water was used in normal irrigation models and how deep the salts were leached under such normal irrigation models. Through analyzing large amount of data, especially those data coming from reclaimed saline soils, the depth and index for salic horizon should be redefined to keep the reclaimed saline soils in the saline taxa of soil classification systems. In this chapter, we examined the criteria of saline soil classification and made some suggestions by citing other scholar’s research results published in the scientific literature.

This study was conducted to verify the application of indigenous knowledge of Imugan farmers in soil classification in the Imugan watershed of Sta Fe, Nueva Vizcaya. The results were further compared with the scientific knowledge on soil classification. Drawing out the indigenous knowledge was made through the use of participatory rural appraisal techniques such as focus group discussions, key informant interview, and transect walk. Field observation was also done. On the other hand, scientific knowledge included soil profiling, characterization and soil laboratory analysis. Criteria used by Imugan Farmers in soil classification are their experiences supported by their ability to observe attributes of soil resource. This is their way to identify the best use, and appropriate management practices of the soil resource. Scientific soil classification system is a thorough process of soil characterizations that investigates not only the surface soil’s properties, its genesis and chemical properties but also subsoil’s characteristics. This expensive and rigorous procedure is intended to aid decision making on the land‘s best use and crop choice. The two systems of soil classification- knowledge that is tested through time combined with knowledge formed from scientific analysis- may have differences, but combining them together in the framework of soil classification will benefit Imugan farmers. The combined system of soil classification provide detail information about nutrient deficiency and attributes of each soil type, the variety of crops suitable for each soil based on farmers’ preference and appropriate inputs in raising crops that are less or not suitable in a given soil.