Soil Profile Description Otto Spaargaren ISRIC – World Soil Information Wageningen The Netherlands

Why soil profile descriptions ? In surveys: as typical example of soil mapping unit or of one of its components For research: as baseline record to illustrate the environmental setting and relationships between the soil attributes For land resource development: as base for building geo-referenced land information systems

Guidelines FAO Guidelines for Soil Profile Description. 3rd Edition. 1990 – English 1993 – French

Purpose of the FAO Guidelines To enhance standardization and uniformity of soil profile descriptions, in order to facilitate cross-references and comparison between soil descriptions To contribute, through the objective description and recording of soil properties, both to the understanding of the land of which the soil forms part, and to the reliable transfer of technology

Sources for the FAO Guidelines USDA Soil Survey Manual Revised Legend of the Soil Map of the World Keys to Soil Taxonomy Australian Soil and Land Survey Field Handbook

Content of the FAO Guidelines General information about the soil, both administratively and environmentally Description of the individual soil horizons Linkage to computerized information systems, in particular the FAO-ISRIC Soil Database (SDB)

General Information Section Registration and location Soil classification Landform and topography Land use and vegetation Parent material Surface characteristics Soil-water relationships

General information (1) : Registration and location Profile number Soil profile description status Date of description Author(s) Soil unit Location Elevation Map sheet number and grid reference Coordinates

General information (2) : Soil classification Soil taxonomic classification WRB reference group name FAO Legend (1974) and Revised Legend (1988) Soil Map of the World Soil Taxonomy (1999) National Soil climate

General information (3) : Landform and topography Land element Position Slope Micro-topography Soil-landscape sequential relationships

General information (4) : Land use and vegetation Human influence Vegetation

General information (5) : Parent material Unconsolidated material Rock type Effective soil depth

General information (6) : Surface characteristics Rock outcrops Surface coarse fragments Erosion Surface sealing Surface cracks Other surface characteristics

General information (7) : Soil-water relationships Drainage class Internal drainage External drainage Flooding Groundwater Moisture conditions of the soil

Soil horizon description Horizon designation and dimensions Soil colour Primary constituents Organization of the constituents Voids (porosity) Concentrations Biological activity Soil reaction Samples

Soil horizon description (1) : Designation and dimensions Horizon symbol – H, O, A, E, B, C and R master horizon nomenclature, and the subordinate characteristics within master horizons and layers Horizon boundary – depth, distinctness and topography

Soil horizon description (2) : Master horizon designation (1) Organic horizons: H or O H = wet O = dry

Soil horizon description (3) : Master horizon designation (2) Mineral horizons: A (organic matter) E (eluviation) B (illuviation) C (parent material, unconsolidated)

Soil horizon description (4) : Master horizon designation (3) Mineral horizons: R (parent rock)

Soil horizon description (5) : Subordinate characteristics of master horizons (1): c Concretions or nodules f Frozen soil g Gleying evidenced by mottling h Accumulation of organic matter j Jarosite mottling k Accumulation of carbonates m Cementation or induration

Soil horizon description (6) : Subordinate characteristics of master horizons (2): n Accumulation of sodium o Residual accumulation of sesquioxides p Ploughing or other disturbance q Accumulation of silica r Strong reduction s Illuvial accumulation of sesquioxides t Accumulation of silicate clay

Soil horizon description (7) : Subordinate characteristics of master horizons (3): v Occurrence of plinthite w Development of colour or structure x Fragipan character y Accumulation of gypsum z Accumulation of salts more soluble than gypsum

Soil horizon description (8) : Soil colour Matrix colour – hue, value and chroma, both dry and moist, according to the Munsell Soil Color Charts, or the Revised Standard Soil Color Charts Mottling – abundance, size, contrast, boundary and colour (dry and moist)

Soil horizon description (9) : Primary constituents Texture of the fine earth fraction – sand, loamy sand, sandy loam, loam, silt loam, silt, silty clay loam, silty clay, clay loam, sandy clay loam, sandy clay, clay Rock fragments – gravel, stones, boulders

Soil horizon description (10) : Organization of soil constituents Soil structure – grade, size and type Types: single grain, massive, granular, prismatic, columnar, angular blocky, subangular blocky, platy, rock structure, stratified structure Consistence – dry, moist and wet

Soil horizon description (11) : Voids (porosity) Voids include all space in the soil. They are described in terms of Type Size Abundance Continuity Orientation

Soil horizon description (12) : Concentrations Cutanic features – clay, humus, pressure faces, slickensides, iron coatings Cementation and compaction – continuity, structure, nature, degree Mineral nodules – abundance, kind, size, shape, hardness, nature, colour

Soil horizon description (13) : Biological activity Roots – abundance and size Biological features – abundance and kind

Soil horizon description (14) : Soil reaction Presence of carbonates – non-calcareous, slightly calcareous, moderately calcareous, strongly calcareous and extremely calcareous (tested with 10% HCl) Field pH – Hellige test, field pH meter, NaF test for volcanic soils

Soil horizon description (15) : Samples Basically, there are two methods of collecting soil samples: Sampling in equal proportions over the whole horizon (recommended method) Sampling in equal proportions within a depth of 20cm, either from the centre of the horizon, or at balanced intervals if the horizon exceeds 50cm thickness

Linkages (1) : FAO-ISRIC Soil Database (SDB) Permits storage and retrieval of large amounts of field and analytical data Provides a flexible coding system to accommodate local needs Can be linked to geographical information systems (GIS), automated land evaluation packages, or statistical programs

Linkages (2) : FAO-ISRIC Soil Database (SDB) The following data sets can be stored in the SDB: Field descriptions: coded information on site and profile characteristics Standard soil analytical results: chemical analyses, soluble salts Soil physical analytical results: infiltration and water retention data

New developments In 2002, a new “Field Book for Describing and Sampling Soils” (Version 2.0) was issued by the National Soil Survey Center of the USDA’s Natural Resources Conservation Service

New developments In 2003, a “Students Guide for Soil Description, Soil Classification and Site Evaluation” was prepared by R. Jahn, H.-P. Blume and V.B. Asio, for workshops and international seminars in Poland and The Philippines

New developments In 2003, FAO and CSIC issued “The Multilingual Soil Profile Database” (SDBm Plus), an upgraded and expanded Windows version of the SDBm software, which had replaced the DOS- based version of SDB

The USDA Field Book Very comprehensive, with numerous useful diagrams and illustrations Introduces new descriptive elements, such as “redoximorphic features”, “soil crusts”, and “odor” Provides little linkage to the FAO Guidelines (e.g. no comparison between particle size classes of USDA and FAO)

The Student Guide Builds strongly on the 1990 Guidelines, with elements of the “Kartieranleitung” (Germany, 1994), SOTER (1995), WRB (1998), and Soil Taxonomy (1999) Links observation to interpretation Biased towards soil conditions in temperate regions

SDBm Plus (1) Re-designed and re-written as Windows application Multilingual (English, French, Spanish, German) Detailed soil profile characterization

SDBm Plus (2) Possibility of monitoring the temporal variability of analytical, physical and hydraulic soil properties Metadata facility for describing analytical methods and procedures used Linkage between database and land evaluation/geographical information systems (LES/GIS)

Conclusions (1) There is a need to update the 1990 FAO Guidelines for Soil Profile Description, in order to accommodate new knowledge and needs for recording soil properties The new USDA Field Book and the Student Guide provide good practical material to be incorporated in a 4th Edition of the Guidelines, enhancing the interpretative value

Conclusions (2) Special attention should be paid to the consequences of changes with respect to the older versions of the Guidelines (see, for example, the change in textural boundaries in 1990) Care should be taken that presented methods are valid worldwide, or that users are cautioned for the limited validity of methods given

Afterthought “In view of the high costs of soil survey, soil profile descriptions should be made as detailed and comprehensive as possible, so that they can serve multiple purposes.”