Pedology explained: soil formation, profile layers, properties, and management insights
- Our Sustainable Farm (OSF)
An Overview of Pedology
Pedology is a subfield of soil science that derives its name from the Greek terms “pedon” (soil) and “logos” (study). It is largely focused with knowing and characterizing soil creation and evolution processes. Pedology also investigates the theoretical frameworks used to simulate soil bodies, especially in the setting of the natural environment. (Contributors to Wikipedia, 2023) Understanding soil formation, determining fertility, and making informed land management decisions all rely on pedology. Pedologists assist to environmental impact assessments, soil conservation efforts, and climate change mitigation measures by studying soils. The information gained from pedology allows us to maintain and manage soils in a sustainable manner, ensuring their critical role in agriculture, ecosystems, and the overall health of our planet. 2021 (Borneman) Edaphology, or the study of how soil affects living creatures, is closely related to pedology, or the study of soil.


Soil Formation Methods
Weathering and erosion processes create soil minerals from rocks (parent material). Water, wind, temperature, creatures, and chemical interactions all contribute to the breakdown of parent material, which forms the foundation of soil. (2013, Queensland)

The Role of Weathering in Soil Formation
Parent material, climate, live organisms, geography, and time all have an impact on soil formation. Weathering and erosion processes generate soil particles from parent material, which consists of rocks and minerals. The transport of chemicals and organic matter in the soil is influenced by climate factors such as precipitation and temperature. Vegetation and microbes, for example, contribute to soil formation through root systems, decomposition, and nitrogen cycling. Topography has an impact on soil growth through influencing moisture and temperature conditions. Soils weather and mature through time, with older soils demonstrating stronger weathering and development variables impacting soil formation.


Horizons and Soil Profile

Profile Of The Soil
The soil profile is a vertical slice of soil that extends from the ground surface to bedrock. Horizons are distinct layers that make up a horizon. Horizons are distinguished by observable features such as color, texture, structure, and thickness. The arrangement of layers above the bedrock is referred to collectively as the soil’s solum.
Soil Horizons/Layers
The highest layer of topsoil is mostly made up of organic elements. It has a high organic matter concentration (approximately 20-30%) and is often dark brown or black in color due to the organic content.
The uppermost mineral horizon is made up of organic matter and degraded materials. It has a deeper color and contains humified organic matter (humus), which helps seed germination and is inhabited by microbes.
The horizon of maximal eluviation (removal of constituents) by percolating water. It is composed of nutrients that have leached from the O and A horizons.
Harder and more compact subsurface horizon than topsoil, with less humus, soluble minerals, and organic matter. Represents the horizon of greatest illuviation (material accumulation) of particular components.
Unconsolidated material beneath the solum, which may accumulate materials such as calcium, magnesium, carbonates, and cementation.

The Location with The Least Weathering
Parent substance or Bedrock: Found below the C horizon. Made up of many sorts of rocks. Represents the solid geological substance from which the soil evolved.
Soil Characteristics
The texture, structure, porosity, chemistry, and color of soil determine its composition, fertility, and suitability for plant growth. Understanding these qualities is essential for good soil management and agricultural activities.
The size of the particles in the soil (sand, silt, clay). Determines the texture and content of the soil. Sandy soils are gritty, silts are smooth like flour, and clays are sticky and moldable. Loams are soils that are a mixture of sand, silt, and clay.
It is influenced by elements such as soil texture, drainage, and water-holding capacity. Sandy soils drain rapidly but might suffer from drought, whereas clay soils retain water for a longer period of time but can become hard when dry.
Describes the clumping of sand, silt, and clay particles and is influenced by organic matter, soil organisms, and soil moisture. Soil structure influences plant growth, air and water movement, root development, and nutrient availability. Good quality soils have fine aggregates and are crumbly, whereas poor quality soils lack structure or have coarse clods.
The presence of pores within the soil that affects air and water movement. Healthy soils have many pores, whereas poor quality soils have few visible pores and may be compacted. Soil management practices can change porosity, affecting drainage and water infiltration.
Clays and organic matter in soil carry negative charges, attracting positively charged nutrients and preventing leaching. Soil pH influences nutrient absorption and plant growth. Soils can be acidic, alkaline, or neutral, and lime is used to reduce acidity.
Soil colors range from black to red to white and can even be blue. Organic matter and iron content influence soil color. Dark topsoil indicates good drainage, while rusty areas and grey patches indicate poor drainage.


Taxonomy and Classification of Soils
The soil order is the highest hierarchical level in soil taxonomy. There are 12 recognized soil orders, each of which represents significant variances in soil origin and properties. The names of the soil orders are followed by the suffix “-sol.” The soil orders are as follows:
Soils containing aluminum and iron. Contains clay accumulation horizons. Forms in places with sufficient moisture and warmth for at least three months of plant growth. Makes up 10% of soils worldwide.
Volcanic ash soils that are relatively new and cover 1% of the world’s ice-free area.
Dry soils that occur under desert settings and have less than 90 days of constant moisture during the growing season.
Nonleached soils with sluggish formation and little organic content; may have caliche or duripan subsurface zones; account for almost 12% of worldwide soils.
Recently produced soils with poorly developed horizons. Found on loose sediments from rivers, beaches, or volcanic ash. Some may have an A horizon on top of bedrock. Account for 18% of soils worldwide.
Permafrost soils with permafrost within two meters of the surface or gelic materials with permafrost within one meter, accounting for 9% of all soils on the planet.
Organic soils, traditionally known as bog soils, account for 1% of all soils on the planet.
Young soils with limited horizon development, with little eluviation and illuviation, accounting for 15% of all soils worldwide.
Soils developed in grasslands and some hardwood woods that are soft, deep, and dark. Have thick A horizons and account for 7% of all soils on the planet.
Soils that have been heavily weathered and are high in iron and aluminum oxides. It is deficient in silica and trace elements.
Formed as a result of intense tropical rains and high temperatures.
Comprise 8% of the world’s soils.
Acidic soils with an organic colloid layer complexed with leached iron and aluminum; often found in coniferous and deciduous woodlands in cooler climes. Represent 4% of all soils on the planet.
Acid soils found in the humid tropics and subtropics. Low in calcium, magnesium, and potassium. Highly worn but not as much as Oxisols. Make up 8% of world soils.
Clay-rich soils that shrink-swell and produce deep fissures when dry, making farming and construction difficult.

Conservation and Soil Management
Cover cropping, mulching, crop rotation, conservation tillage, ridges/terraces/contours, strip cropping/windbreaks, and residue management are all important for protecting soil health, reducing erosion, and encouraging sustainable agriculture. These approaches improve soil structure, organic matter content, microbial activity, and water retention while reducing soil displacement, runoff, and wind erosion. We can conserve our important soil resources and assure long-term agricultural productivity by implementing these steps. (Ogunsola and colleagues, 2020)


Pedology Applications
Agriculture
Pedology gives useful insights into soil qualities, nutrient content, and fertility, allowing farmers to make informed crop selection, fertilization, and irrigation decisions.
Understanding pedology assists in the implementation of proper soil conservation methods, erosion control measures, and soil improvement techniques, increasing agricultural output and sustainability.
Agroforestry
Pedology assists in determining soil qualities and suitability for growing various tree species, allowing for informed decisions in agroforestry planning and establishment.
Understanding pedology can help you manage nutrient cycling in agroforestry systems, optimize tree growth, and improve the ecosystem services offered by trees.
Agroforestry
Pedology is critical in identifying polluted soils, determining the level of contamination, and creating effective soil remediation solutions to limit environmental concerns.
Understanding pedology helps in analyzing soil-water relationships such as infiltration, runoff, and water-holding capacity, which contributes to better water management and conservation.
Land-use planning
Pedological information aids in the evaluation of soil properties, drainage characteristics, and limitations, thereby supporting land-use planning decisions for a variety of purposes such as urban development, agriculture, and conservation.
Pedology aids in the rehabilitation of degraded lands, the selection of appropriate vegetation, and the implementation of soil conservation practices to restore ecosystem functions and promotes land use sustainability.

Conclusion
Finally, soil knowledge and comprehension, particularly in the subject of pedology, are extremely important for a variety of modern applications. Soil characteristics, nutrient content, and soil-water interactions provide critical information for productive agricultural operations, agroforestry planning, managing environmental challenges, and making educated land-use decisions. Using pedological knowledge supports sustainable behaviors, increases productivity, saves resources, and reduces environmental dangers. As a result, whether in agriculture, agroforestry, environmental management, or land-use planning, a fundamental understanding of pedology is required for professionals working in these industries to ensure optimal outcomes and long-term development.


Summary
Pedology is a subfield of soil science that focuses on understanding and characterizing soil creation and evolution processes. It investigates theoretical frameworks used to simulate soil bodies, especially in the natural environment. Understanding soil formation, determining fertility, and making informed land management decisions all rely on pedology. Pedologists assist in environmental impact assessments, soil conservation efforts, and climate change mitigation measures by studying soils. The information gained from pedology allows us to maintain and manage soils in a sustainable manner, ensuring their critical role in agriculture, ecosystems, and the overall health of our planet.
Soil formation methods include weathering and erosion processes, which create soil minerals from rocks (parent material). Weathering and erosion processes generate soil particles from parent material, which consists of rocks and minerals. The transport of chemicals and organic matter in the soil is influenced by climate factors such as precipitation and temperature. Vegetation and microbes contribute to soil formation through root systems, decomposition, and nitrogen cycling. Topography has an impact on soil growth through influencing moisture and temperature conditions. Soils weather and mature through time, with older soils demonstrating stronger weathering and development variables impacting soil formation.
Soil characteristics include texture, structure, porosity, chemistry, and color. Understanding these qualities is essential for good soil management and agricultural activities. Soil texture determines the texture and content of the soil, while soil formation influences plant growth, air and water movement, root development, and nutrient availability. Soil structure describes the clumping of sand, silt, and clay particles and is influenced by organic matter, soil organisms, and soil moisture. Soil porosity affects air and water movement, and soil chemistry influences nutrient absorption and plant growth.


Soil taxonomy and classification of soils are divided into 12 recognized soil orders: alfisol, and oxisol. Alfisol is a soil containing aluminum and iron, while oxisol is a soil with heavy weathering and low iron and aluminum oxides. Spodosol is an acidic soil with an organic colloid layer complexed with leached iron and aluminum, and ultisol is an acid soil found in humid tropics and subtropics. Vertisol is a clay-rich soil that shrinks and produces deep fissures when dry, making farming and construction difficult. Soil conservation and management are crucial for maintaining soil health, reducing erosion, and promoting sustainable agriculture.
Pedology plays a vital role in agriculture, assisting in soil analysis, management, agroforestry, and nutrient cycling. It also helps in identifying soil pollution, remediation, and soil-water interactions. Understanding pedology also aids in land-use planning, assessing soil properties, and promoting land rehabilitation and restoration. By implementing these practices, we can conserve soil resources and ensure long-term agricultural productivity.
REFERENCES
Wikipedia contributors. (2023). Pedology. Wikipedia.
Borneman, E. (2021). Pedology. Geography Realm.
Queensland, C. O. S. O. (2013, October 8). How soils form. Environment, Land and Water | Queensland Government.
Soil Weathering and Soil Formation | Soils – Part 1: The Origin and Development of Soil (How Soil Gets a Life and a Name) – passel. (n.d.).
Tiwari, S. (2023). SOIL PROFILE- DIFFERENT HORIZONS. Agriculture Wale.
Soil properties. (n.d.). Science Learning Hub
Ogunsola, O. A., Adeniyi, O. D., & Adedokun, V. (2020). Soil Management and Conservation: An Approach to Mitigate and Ameliorate Soil Contamination. IntechOpen eBooks.