Crushed Stone – granular material, resulting from the mechanical crushing of rock, boulders or large cobble stones, of which substantially all faces have been fractured by the crushing operations. Freeze – an increase in the load capacity of a pile after it has been driven. Respiration: The biochemical processes by which all living organisms derive energy from food or stored reserves by taking oxygen from the environment and giving off carbon dioxide. Sieve – a device, similar in concept to a strainer, that has openings in the wire mesh of a designated size. Acidic: A soil, compost, or liquid with a pH between 0 and 7.0 (on a scale of 0.0-14.0). Humin (HN): A fraction of soil organic matter that cannot be extracted from soil with dilute alkali or acid. Sand – soil particles that will pass the No. Colloids – small particles in suspension that will not settle out due to gravity. ¾Soil Layer - A layer in the soil deposited by a Because of this, it has many definitions. Total Nitrogen: Total of all forms of nitrogen in the soil. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. It is equal to the slope of the tangent or the secant of a stress-strain curve. One of the goals of sustainable agriculture is to work with the natural cycles of the terrestrial ecosystems, especially with the soil biology to enhance the efficiency of agricultural management practices. Coefficient of Compressibility – the rate of change of void ratio relative to applied pressure. See more. It is an indicator of soil ecosystem disturbance. It is found for a sample by dividing the weight of the water by the weight of the solid particles. 4 (4.75-mm) sieve and be retained on the No.  The term seepage is usually restricted to the very slow movement of groundwater. No-till farming, by definition, means that the soil has not been disturbed since the prior harvest of a crop. Soil aggregates are usually greater than ten millimeters in diameter and formed by natural forces (such as alternate wetting-drying) and organic substances derived from root exudates, roots, soil animals and microbial by-products which cement primary particles into smaller aggregates or smaller aggregates into larger particles, such as macroaggregates. Dig down deep into any soil, and you’ll see that it is made of layers, or horizons (O, A, E, B, C, R). Glacial Till – Man-made fabrics designed for use in soil stabilization and control. Footing – portion of a structure that transmits loads directly to the soil. Mycelium: A string-like mass of individual fungal or actinomycetes hyphae. Mycelium is the vegetative part of a fungus, consisting of a mass of branching, threadlike hyphae. In other words, high DH means the organic matter is more resistant to decomposition. Soil Profile A vertical section of the earth's highly weathered upper surface often showing several distinct layers or horizons. Foundation – Part of a structure that transmits load to soil or rock. Piezometer – an instrument for measuring pressure head in soil deposits. Fungal hyphae are important to extract nutrients, especially micronutrients, to support growth in poor quality soil. Perched Water Table – groundwater separated from an underlying body of groundwater by a concave and relatively impervious soil or rock layer. Rhizosphere: A soil zone near the plant roots where microbes flourish in greater numbers and have more activity than in the bulk soil. Fines – portion of a soil finer than a No. Anaerobic: Absence of oxygen or growing in the absence of oxygen. The common air pollutants are ground-level ozone, carbon monoxide, sulfur dioxide, nitrogen oxide (e.g. Microaggregates: Soil aggregates less than 250 micrometers in size consisting of primary particles, plant roots, and humin cemented together. Expansive Soil – a clayey soil that expands when wetted and contracts when dried. To place an order call: 800.296.3005 Failure Criterion – mechanical condition under which solid materials fail by facturing or by deforming beyond some specified limit. Soil Stabilization – chemical or mechanical treatment designed to improve stability of a soil mass or to deposition or weathering, or both. With higher costs for labor, seed, fuel, fertilizer, and pesticides, agricultural producers are looking for more economical ways to improve crop production and maintain ecosystem sustainability. The secondary units are classified on the basis of size (microaggregates are the smallest and macroaggregates are the largest) and shape. Sustainable agriculture and soil quality are terms that are increasingly important to modern farming. Anaerobesis of soil is also responsible for widespread soil-borne diseases. Typically considered nonliving and are capable of growth only in a living cell. It is prominent in woody or mature tissues and increases as a plant ages. Also applies to cone penetration tests when the cone cannot advance further. Dig down deep into any soil, and you’ll see that it is made of layers, or horizons (O, A, E, B, C, R). Aggregates: Primary soil particles (sand, silt, and clay) held together in a single mass or cluster, such as a crumb, block, prism or clod using organic matter as cementing material. Shelby-Tube Sampler – device used for obtaining soil samples, usually undisturbed and from some depth beneath the surface. Bulk Density (ρb): The mass (weight) of unit soil divided by the total volume occupied. We work with families and children, farmers and businessowners, community leaders and elected officials to build better lives, better businesses and better communities to make Ohio great. Soil Texture: Relative portion of sand, silt, and clay in a given amount of soil. Protozoa are more common in conventional tilled or disturbed soils where they outnumber the nematodes. ; commonly used to improve physical condition. Landslide – the downward and outward sliding or movement of a soil mass of earth or rock, or a mixture of both. Capillary Rise – the height above a free water elevation to which water will rise due to capillary action. Porosity – the ratio of volume of voids in a rock or soil to its total volume. Optimum Moisture Content – water content at which a soil can be compacted to a maximum dry unit weight using a specific compactive effort. Consolidation – the process of gradual reduction in volume of a soil mass resulting from an increase in compressive stress. Photo courtesy of Eliot, USDA-NRCS. Air Quality: Defined as a measure of the amount or concentration of pollutants emitted into the atmosphere and the dispersion potential of an area to dilute those pollutants. It typically ranges from 0.5 to 5% in soil. Soil quality is analogous to soil health. The Shelby-tube sampler is a tube that is pressed into the soil to be sampled, usually by a drilling rig. Manhole – a hole, usually with a cover, through which a person may enter a sewer, drain, steam boiler, etc., especially one located in a city street. Hydrostatic Pore Water Pressure – the portion of the pore water pressure that is due to the force of gravity acting on the water above. Clay Soil – fine-grained soil finer than 0.002 mm (0.005 mm in some cases) that exhibits plasticity with a range of water contents. As soils develop over time, layers (or horizons) form a soil profile. Soil Profile There are different types of soil, each with its own set of characteristics. Select Fill – soil especially selected for its physical characteristics and used as a construction base, or to replace soil removed during excavation. Soil particle density is lower for soils with high organic matter content, and is higher for soils with high iron-oxides content. Infiltration: The entry of water into the soil. Combined Footing – a spread footing that supports more than one column. Bacteria dominate in disturbed (e.g. Aquifer – groundwater reservoir found in a water-bearing geologic formation. Most species feed on bacteria, fungi, or dead microbial particles. Soil organic matter decomposition releases nutrients, especially N, but it also destroys soil structure and macropores leading to soil compaction and decreased soil organic matter levels. Soil Quality Index: Integrated measure of soil quality by transforming and combining selected core biological, chemical, and physical properties into a single index to evaluate a soil's functional capability. Conventional tillage means that the soil is physically turned over (or loosened), and oxygenate. Subsidence – sinking of a part of the earth’s crust and downward displacement of the overburden (rock, soil, or both) lying above an underground excavation. CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. Gravel – rounded or semirounded particles of rock that pass a 3-in. These pollutants can harm field crops, public health, birds and other animals, and the environment, and cause property damage. Horizon – One of the layers of a soil profile, distinguished  principally by its texture, color, structure and chemical content. An ideal soil has a bulk density of about 1.25 g cm-3. Also refers to the condition of the soil, including its ecosystems (minerals, nutrients, and microbial activity), pH, and structure. CFAES Diversity  |  Nondiscrimination notice  |  Site Map. Lignin is a very complex energy-rich molecule and varies greatly in structure, making it hard to decompose. 200 U.S. standard sieve. Carbon-Nitrogen Ratio (C/N): Ratio of the mass (weight) of organic carbon to the mass of total nitrogen in the soil, plants, or any other organic compounds. Thus, simply rewetting the soil will not restore its original properties. Soil is used by people in many ways. If the pH of the soil is 6.5 or higher, all the total carbon is considered to be organic carbon. Outcrop – Exposed portions of bedrock at ground surface. Total Phosphorus (TP): Total of all forms of phosphorus in the soil including organic (inositol, phospholipids, etc.) distance, and the number of hammer blows (N) are noted. Sieve Analysis – use of a series of sieves to determine the particle size distribution of a soil. In an ideal soil, the total pore space should be about 50% (composed of air and water) while the solid phases (sand, silt, clay, and organic matter) make up the other 50% of soil volume.  Normally, a temporary measure. As a result, nutrients are generally more available and absorbed by plant roots. Cone Penetration Test (CPT) – an in-situ test for determining soil properties. Soil Facts — Definitions of soil and soil survey, information on careers, some basics on soil formation and classification, and a soil science glossary.. Handbook for Collegiate Soils Contest (PDF; 116 KB) — A reference training document developed for the Southeastern Region Collegiate Soil Judging … Transported Soil – soil transported from the place of its origin by wind, water or ice. 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