DETAILS OF AGRICULTURAL AND SOIL SCIENCE & PRESENT OF SOIL NACTURE AND STRUCTRES AND CHARITERS
Indrotiction
Fields of study
Research
Mapping -Soil survey -Background- Classification -
Soil classification -Overview -Engineering Soil science-
History
Areas of practice
Fields of application in soil science
Related disciplines
Depression storage capacity
Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.[1]
The main branches of soil science are pedology ― the study of formation, chemistry, morphology, and classification of soil ― and edaphology ― the study of how soils interact with living things, especially plants. Sometimes terms which refer to those branches are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned. Indeed, engineers, agronomists, chemists, geologists, physical geographers, ecologists, biologists, microbiologists, silviculturists, sanitarians, archaeologists, and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences.[1]
Soil scientists have raised concerns about how to preserve soil and arable land in a world with a growing population, possible future water crisis, increasing per capita food consumption, and land degradation.[2]
Fields of study
Soil occupies the pedosphere, one of Earth's spheres that the geosciences use to organize the Earth conceptually. This is the conceptual perspective of pedology and edaphology, the two main branches of soil science. Pedology is the study of soil in its natural setting. Edaphology is the study of soil in relation to soil-dependent uses. Both branches apply a combination of soil physics, soil chemistry, and soil biology. Due to the numerous interactions between the biosphere, atmosphere and hydrosphere that are hosted within the pedosphere, more integrated, less soil-centric concepts are also valuable. Many concepts essential to understanding soil come from individuals not identifiable strictly as soil scientists. This highlights the interdisciplinary nature of soil concepts.
Research
Exploring the diversity and dynamics of soil continues to yield fresh discoveries and insights. New avenues of soil research are compelled by a need to understand soil in the context of climate change,[3][4] greenhouse gases, and carbon sequestration.[3] Interest in maintaining the planet's biodiversity and in exploring past cultures has also stimulated renewed interest in achieving a more refined understanding of soil.
Mapping
Background
Soil surveys apply the principles of soil science and draw heavily from geomorphology, theories of soil formation, physical geography, and analysis of vegetation and land use patterns. Primary data for the soil survey are acquired by field sampling and by remote sensing. Remote sensing principally uses aerial photography, but LiDAR and other digital techniques are steadily gaining in popularity. In the past, a soil scientist would take hard-copies of aerial photography, topographic maps, and mapping keys into the field with them. Today, a growing number of soil scientists bring a ruggedized tablet computer and GPS into the field with them. The tablet may be loaded with digital aerial photos, LiDAR, topography, soil geodatabases, mapping keys, and more.
Publication
- a brief overview on how to use the survey
- a general soil map for comparing the sustainability of large sections of the county
- a detailed map with specific soil series outlined and indexed
- a section on the use and management of soils
- tables describing the physical features and environment of the county
- tables containing land use suitability based on standards set by the Natural Resources Conservation Service.
See alsoClassification
The term soil survey may also be used as a noun to describe the published results. In the United States, these surveys were once published in book form for individual counties by the National Cooperative Soil Survey. Today, soil surveys are no longer published in book form; they are published to the web and accessed on NRCS Web Soil Survey where a person can create a custom soil survey. This allows for rapid flow of the latest soil information to the user. In the past it could take years to publish a paper soil survey. Today it takes only moments for changes to go live to the public. The most current soil survey data is made available for high end GIS users such as professional consulting companies and universities.
Typical information in a published county soil survey includes the following:[1]
The information in a soil survey can be used by farmers and ranchers to help determine whether a particular soil type is suited for crops or livestock and what type of soil management might be required. An architect or engineer might use the engineering properties of a soil to determine whether it is suitable for a certain type of construction. A homeowner may even use the information for maintaining or constructing their garden, yard, or home.
Soil survey information can be used to predict or estimate the potentials and limitations of soils for many specific uses. A soil survey includes an important part of the information that is used to make workable plans for land management. The information must be interpreted to be usable by professional planners and others. Predictions based on soil surveys serve as a basis for judgment about land use and management for areas ranging from small tracts to regions of several million acres. These predictions, however, must be evaluated along with economic, social, and environmental considerations before they can be used to make valid recommendations for land use and management.[2]
Soil classification
deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.
Overview
Soil classification is a dynamic subject, from the structure of the system, to the definitions of classes, to the application in the field. Soil classification can be approached from the perspective of soil as a material and soil as a resource.
Inscriptions at the temple of Horus at Edfu outline a soil classification used by Tanen to determine what kind of temple to build at which site.[1] Ancient Greek scholars produced a number of classification based on several different qualities of the soil.[2]
Engineering
Soil science
Main article: Soil science
- Stable Rock: natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed.
- Type A - cohesive, plastic soils with unconfined compressive strength greater than 1.5 ton per square foot (tsf)(144 kPa), and meeting several other requirements (which induces a lateral earth pressure of 25 psf per ft of depth[14])
- Type B - cohesive soils with unconfined compressive strength between 0.5 tsf (48 kPa) and 1.5 tsf (144 kPa), or unstable dry rock, or soils which would otherwise be Type A (lateral earth pressure of 45 psf per ft of depth[14])
- Type C - granular soils or cohesive soils with unconfined compressive strength less than 0.5 tsf (48 kPa) or any submerged or freely seeping soil or adversely bedded soils (lateral earth pressure of 80 psf per ft of depth[14])
- Type C60 - A subtype of Type C soil, though is not officially recognized by OSHA as a separate type, induces a lateral earth pressure of 60 psf per ft of depth
Geotechnical engineers classify soils according to their engineering properties as they relate to use for foundation support or building material. Modern engineering classification systems are designed to allow an easy transition from field observations to basic predictions of soil engineering properties and behaviors.
The most common engineering classification system for soils in North America is the Unified Soil Classification System (USCS). The USCS has three major classification groups: (1) coarse-grained soils (e.g. sands and gravels); (2) fine-grained soils (e.g. silts and clays); and (3) highly organic soils (referred to as "peat"). The USCS further subdivides the three major soil classes for clarification. It distinguishes sands from gravels by grain size, classifying some as "well-graded" and the rest as "poorly-graded". Silts and clays are distinguished by the soils' Atterberg limits, and thus the soils are separated into "high-plasticity" and "low-plasticity" soils. Moderately organic soils are considered subdivisions of silts and clays and are distinguished from inorganic soils by changes in their plasticity properties (and Atterberg limits) on drying. The European soil classification system (ISO 14688) is very similar, differing primarily in coding and in adding an "intermediate-plasticity" classification for silts and clays, and in minor details.
Other engineering soil classification systems in the United States include the AASHTO Soil Classification System, which classifies soils and aggregates relative to their suitability for pavement construction, and the Modified Burmister system, which works similarly to the USCS but includes more coding for various soil properties.[3]
A full geotechnical engineering soil description will also include other properties of the soil including color, in-situ moisture content, in-situ strength, and somewhat more detail about the material properties of the soil than is provided by the USCS code. The USCS and additional engineering description is standardized in ASTM D 2487.[4]
For soil resources, experience has shown that a natural system approach to classification, i.e. grouping soils by their intrinsic property (soil morphology), behaviour, or genesis, results in classes that can be interpreted for many diverse uses. Differing concepts of pedogenesis, and differences in the significance of morphological features to various land uses can affect the classification approach. Despite these differences, in a well-constructed system, classification criteria group similar concepts so that interpretations do not vary widely. This is in contrast to a technical system approach to soil classification, where soils are grouped according to their fitness for a specific use and their edaphic characteristics.
Natural system approaches to soil classification, such as the French Soil Reference System (Référentiel pédologique français) are based on presumed soil genesis. Systems have developed, such as USDA soil taxonomy and the World Reference Base for Soil Resources,[5][6] which use taxonomic criteria involving soil morphology and laboratory tests to inform and refine hierarchical classes. Another approach is numerical classification, also called ordination, where soil individuals are grouped by multivariate statistical methods such as cluster analysis. This produces natural groupings without requiring any inference about soil genesis.
In soil survey, as practiced in the United States, soil classification usually means criteria based on soil morphology in addition to characteristics developed during soil formation. Criteria are designed to guide choices in land use and soil management. As indicated, this is a hierarchical system that is a hybrid of both natural and objective criteria. USDA soil taxonomy provides the core criteria for differentiating soil map units. This is a substantial revision of the 1938 USDA soil taxonomy which was a strictly natural system. The USDA classification was originally developed by Guy Donald Smith, director of the U.S. Department of Agriculture's soil survey investigations.[7] Soil taxonomy based soil map units are additionally sorted into classes based on technical classification systems. Land Capability Classes, hydric soil, and prime farmland are some examples.
The European Union uses the World Reference Base for Soil Resources (WRB), currently the fourth edition is valid.[5] According to the first edition of the WRB (1998),[8] the booklet "Soils of the European Union"[9] was published by the former Institute of Environment and Sustainability (now: Land Resources Unit, European Soil Data Centre/ESDAC).
In addition to scientific soil classification systems, there are also vernacular soil classification systems. Folk taxonomies have been used for millennia, while scientifically based systems are relatively recent developments.[10] Knowledge on the spatial distribution of soils has increased dramatically. SoilGrids is a system for automated soil mapping based on models fitted using soil profiles and environmental covariate data. On a global scale, it provides maps at 1.00–0.25 km spatial resolution.[11] Whether sustainability might be the ultimate goal for managing the global soil resources, these new developments require studied soils to be classified and given its own name.[12]
The U.S. Occupational Safety and Health Administration (OSHA) requires the classification of soils to protect workers from injury when working in excavations and trenches. OSHA uses three soil classifications plus one for rock, based primarily on strength but also other factors which affect the stability of cut slopes:[13]
Each of the soil classifications has implications for the way the excavation must be made or the protections (sloping, shoring, shielding, etc.) that must be provided to protect workers from collapse of the excavated bank
In 1998, the World Reference Base for Soil Resources (WRB) replaced the FAO soil classification as the international soil classification system. The currently valid version of WRB is the 4th edition, 2022.[5] The FAO soil classification, in turn, borrowed from modern soil classification concepts, including USDA soil taxonomy.
WRB is based mainly on soil morphology as an expression of pedogenesis. A major difference with USDA soil taxonomy is that soil climate is not part of the system, except insofar as climate influences soil profile characteristics.
Many other classification schemes exist, including vernacular systems. The structure in vernacular systems is either nominal (giving unique names to soils or landscapes) or descriptive (naming soils by their characteristics such as red, hot, fat, or sandy). Soils are distinguished by obvious characteristics, such as physical appearance (e.g., color, texture, landscape position), performance (e.g., production capability, flooding), and accompanying vegetation.[6] A vernacular distinction familiar to many is classifying texture as heavy or light. Light soil content and better structure take less effort to turn and cultivate. Light soils do not necessarily weigh less than heavy soils on an air dry basis, nor do they have more porosity.
History
The earliest known soil classification system comes from China, appearing in the book Yu Gong (5th century BCE), where the soil was divided into three categories and nine classes, depending on its color, texture and hydrology.[7]
Contemporaries Friedrich Albert Fallou (the German founder of modern soil science) and Vasily Dokuchaev (the Russian founder of modern soil science) are both credited with being among the first to identify soil as a resource whose distinctness and complexity deserved to be separated conceptually from geology and crop production and treated as a whole. As a founding father of soil science, Fallou has primacy in time. Fallou was working on the origins of soil before Dokuchaev was born; however Dokuchaev's work was more extensive and is considered to be the more significant to modern soil theory than Fallou's.
Previously, soil had been considered a product of chemical transformations of rocks, a dead substrate from which plants derive nutritious elements. Soil and bedrock were in fact equated. Dokuchaev considers the soil as a natural body having its own genesis and its own history of development, a body with complex and multiform processes taking place within it. The soil is considered as different from bedrock. The latter becomes soil under the influence of a series of soil-formation factors (climate, vegetation, country, relief and age). According to him, soil should be called the "daily" or outward horizons of rocks regardless of the type; they are changed naturally by the common effect of water, air and various kinds of living and dead organisms.[8]
A 1914 encyclopedic definition: "the different forms of earth on the surface of the rocks, formed by the breaking down or weathering of rocks".[9] serves to illustrate the historic view of soil which persisted from the 19th century. Dokuchaev's late 19th century soil concept developed in the 20th century to one of soil as earthy material that has been altered by living processes.[10] A corollary concept is that soil without a living component is simply a part of Earth's outer layer.
Further refinement of the soil concept is occurring in view of an appreciation of energy transport and transformation within soil. The term is popularly applied to the material on the surface of the Earth's moon and Mars, a usage acceptable within a portion of the scientific community. Accurate to this modern understanding of soil is Nikiforoff's 1959 definition of soil as the "excited skin of the sub aerial part of the Earth's crust".[11]
Areas of practice
Academically, soil scientists tend to be drawn to one of five areas of specialization: microbiology, pedology, edaphology, physics, or chemistry. Yet the work specifics are very much dictated by the challenges facing our civilization's desire to sustain the land that supports it, and the distinctions between the sub-disciplines of soil science often blur in the process. Soil science professionals commonly stay current in soil chemistry, soil physics, soil microbiology, pedology, and applied soil science in related disciplines.
One exciting effort drawing in soil scientists in the U.S. as of 2004 is the Soil Quality Initiative. Central to the Soil Quality Initiative is developing indices of soil health and then monitoring them in a way that gives us long-term (decade-to-decade) feedback on our performance as stewards of the planet. The effort includes understanding the functions of soil microbiotic crusts and exploring the potential to sequester atmospheric carbon in soil organic matter. Relating the concept of agriculture to soil quality, however, has not been without its share of controversy and criticism, including critiques by Nobel Laureate Norman Borlaug and World Food Prize Winner Pedro Sanchez.
A more traditional role for soil scientists has been to map soils. Almost every area in the United States now has a published soil survey, including interpretive tables on how soil properties support or limit activities and uses. An internationally accepted soil taxonomy allows uniform communication of soil characteristics and soil functions. National and international soil survey efforts have given the profession unique insights into landscape-scale functions. The landscape functions that soil scientists are called upon to address in the field seem to fall roughly into six areas:
- Land-based treatment of wastes
- Septic system
- Manure
- Municipal biosolids
- Food and fiber processing waste
- Identification and protection of environmentally critical areas
- Sensitive and unstable soils
- Wetlands
- Unique soil situations that support valuable habitat, and ecosystem diversity
- Management for optimum land productivity
- Silviculture
- Agronomy
- Native vegetation
- Grazing
- Management for optimum water quality
- Stormwater management
- Sediment and erosion control
- Remediation and restoration of damaged lands
- Mine reclamation
- Flood and storm damage
- Contamination
- Sustainability of desired uses
There are also practical applications of soil science that might not be apparent from looking at a published soil survey.
- Radiometric dating: specifically a knowledge of local pedology is used to date prior activity at the site
- Stratification (archeology) where soil formation processes and preservative qualities can inform the study of archaeological sites
- Geological phenomena
- Altering soils to achieve new uses
- Vitrification to contain radioactive wastes
- Enhancing soil microbial capabilities in degrading contaminants (bioremediation).
- Carbon sequestration
- Environmental soil science
- Pedology
- Soil biology
- Soil chemistry
- Soil biochemistry
- Soil mineralogy
- Soil physics
- Pedotransfer function
- Soil mechanics and engineering
- Soil hydrology, hydropedology
Fields of application in soil science
- Climate change[3]
- Ecosystem studies
- Pedotransfer function
- Soil fertility / Nutrient management
- Soil management
- Soil survey
- Standard methods of analysis
- Watershed and wetland studies
- Land Suitability classification
Related disciplines
- Agricultural sciences
- Agricultural soil science
- Agrophysics science
- Irrigation management
- Anthropology
- Environmental science
- Physical geography
- Geology
- Hydrology
- Waste management
- Wetland science
Depression storage capacity
Depression storage capacity, in soil science, is the ability of a particular area of land to retain water in its pits and depressions, thus preventing it from flowing.[12] Depression storage capacity, along with infiltration capacity, is one of the main factors involved in Horton overland flow, whereby water volume surpasses both infiltration and depression storage capacity and begins to flow horizontally across land, possibly leading to flooding and soil erosion. The study of land's depression storage capacity is important in the fields of geology, ecology, and especially hydrology
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