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The physical properties of soil, in order of decreasing importance for ecosystem services such as crop production, are texture, structure, bulk density, porosity, consistency, temperature, colour and resistivity. [1]
Soil physical properties define movement of air and water/dissolved chemicals through soil, as well as conditions affecting germination, root growth, and erosion processes. Soil physical properties form the foundation of several chemical and biological processes, which may be further governed by climate, landscape position, and land use.
- Soil Texture
- Soil Structure
- Soil Porosity
- Soil Chemistry
- Soil Colour
Soil is made up of different-sized particles. Soil texture refers to the size of the particles that make up the soil and depends on the proportion of sand, silt and clay-sized particles and organic matter in the soil. Sandy soils feel gritty when rubbed between your fingers. Silts feel smooth – a little like flour. Most clays are sticky and mouldab...
Soil structure describes the way the sand, silt and clay particles are clumped together. Organic matter (decaying plants and animals) and soil organisms like earthworms and bacteria influence soil structure. Clays, organic matter and materials excreted by soil organisms bind the soil particles together to form aggregates. Soil structure is importan...
Soil porosityrefers to the pores within the soil. Porosity influences the movement of air and water. Healthy soils have many pores between and within the aggregates. Poor quality soils have few visible pores, cracks or holes. The way in which a soil is managed can affect its porosity. For example, look at areas around your school where students reg...
Clays and organic matter in the soil carry negative charges. Water in the soil dissolves nutrients and other chemicals. Nutrients like potassium and ammonium have positive charges. They are attracted to the negatively charged organic and mineral matter, and this prevents them from being lost through leaching as water moves through the soil. Nitrate...
If you thought that all soils are brown, think again. Soil colours range from black to red to white. Sometimes it can even be blue! Soil colour mostly comes from organic matter and iron. Topsoil is often dark because of organic matter. An even, single colour indicates the soil is well drained. In contrast, rusty spots and grey patches (sometimes ev...
The particles that make up soil are categorized into three groups by size – sand, silt, and clay. Sand particles are the largest and clay particles the smallest. Most soils are a combination of the three. The relative percentages of sand, silt, and clay are what give soil its texture.
Soil texture affects soil behavior, in particular its retention capacity for nutrients and water. Soil components larger than 2.0 mm are considered as rock and gravel and can be included in textural class.For example, a sandy loam soil with 20% gravel would be called a gravelly sandy loam. When the organic component of a soil is substantial ...
Nov 8, 2024 · This article covers the structure, composition, and classification of soils and how these factors affect soil’s role in the global ecosystem. In addition, the two most important phenomena that degrade soils, erosion and pollution, are discussed.
This textbook introduces readers to the basics of soil science, including the physical, chemical, and biological properties of soils; soil formation, classification, and global distribution; soil health, soils and humanity, and sustainable land management.
