# data[].attributes.definition
Alluvium is loose, unconsolidated (not cemented together into a solid rock) soil or sediment that has been eroded, reshaped by water in some form, and redeposited in a non-marine setting. Alluvium is typically made up of a variety of materials, including fine particles of silt and clay and larger particles of sand and gravel. When this loose alluvial material is deposited or cemented into a lithological unit, or lithified, it is called an alluvial deposit.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
Percent base saturation (BS) is the percentage of the Cation Exchange Capacity (CEC) occupied by the basic cations Ca2+, Mg2+ and K+.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

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The mass of many particles of the material divided by the total volume they occupy. The total volume includes particle volume, inter-particle void volume and internal pore volume.

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Bulk electrical conductivity of a medium measured using a sensor such as time domain reflectometry (TDR), as a raw sensor response in the measurement of a quantity like soil moisture.

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USDA particle size distribution category. Less then 0.002 mm diameter fine earth particles. 

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases.

# data[].attributes.definition
The relative permittivity of a material is its (absolute) permittivity expressed as a ratio relative to the permittivity of vacuum. Permittivity is a material property that affects the Coulomb force between two point charges in the material. Relative permittivity is the factor by which the electric field between the charges is decreased relative to vacuum. Likewise, relative permittivity is the ratio of the capacitance of a capacitor using that material as a dielectric, compared with a similar capacitor that has vacuum as its dielectric. Relative permittivity is also commonly known as dielectric constant, a term deprecated in engineering as well as in chemistry.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
Humification index. Hummification is the processes by which organic matter decomposes to form humus. In humus the initial structures or shapes can no longer be recognized. See also humus.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
Hydraulic conductivity, symbolically represented as K, is a property of vascular plants, soils and rocks, that describes the ease with which a fluid (usually water) can move through pore spaces or fractures. It depends on the intrinsic permeability of the material, the degree of saturation, and on the density and viscosity of the fluid.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
When water is in contact with solid particles (e.g., clay or sand particles within soil), adhesive intermolecular forces between the water and the solid can be large and important

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Number of detected neutrons (moderated / unmoderated) per time interval.

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The organic matter component of a complex material.

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Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0 and 100%.

# data[].attributes.definition
c.f. matrix potential. E.g. Tensiometer.

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Soil reponse of a reflected standing electromagnetic wave of a particular frequency which is related to the stored energy within the medium. This is the real portion of the complex dielectric constant.

# data[].attributes.note
Reused Real dielectric constant (Surface water): https://sms-cv.helmholtz.cloud/sms/cv/api/v1/measuredquantities/269/ 
Can also be measured in Soil (e.g. with Stevens HydraProbe sensor)

# data[].attributes.definition
USDA particle size distribution category. 0.5 to 2 mm diameter fine earth particles. 

# data[].attributes.definition
USDA particle size distribution category. 0.002 to 0.5 mm diameter fine earth particles. 

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Soil aggregate stability is a measure of the ability of soil aggregates to resist degradation when exposed to external forces such as water erosion and wind erosion, shrinking and swelling processes, and tillage. Soil aggregate stability is a measure of soil structure and can be impacted by soil management.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

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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.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
Fraction of particles within a soil sample that are greater that 2mm in diameter

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
A soil horizon is a layer parallel to the soil surface, whose physical characteristics differ from the layers above and beneath. Each soil type usually has three or four horizons.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

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The total amount of water, including the water vapor, in an unsaturated soil.

# data[].attributes.definition
Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal residues at various stages of decomposition, cells and tissues of soil organisms, and substances synthesized by soil organisms.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.term
Soil organic matter (SOM) density fractionation

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Density fraction of Soil organic matter (SOM) in soil. Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal residues at various stages of decomposition, cells and tissues of soil organisms, and substances synthesized by soil organisms.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.definition
Soil respiration refers to the production of carbon dioxide when soil organisms respire. This includes respiration of plant roots, the rhizosphere, microbes and fauna.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

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Temperature of soil. Default min/max values according to WMO quality control Guidelines.

# data[].attributes.definition
Soil texture is a classification instrument used both in the field and laboratory to determine soil classes based on their physical texture. Soil texture can be determined using qualitative methods such as texture by feel, and quantitative methods such as the hydrometer method.

# data[].attributes.note
Added to support Critical Zone Observatory (CZO) data use cases. 

# data[].attributes.note
use "Soil moisture" instead. Insert community entry "Soil volumetric water content " there.

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Time domain reflextometry, apparent length divided by probe length. Square root of dielectric

# data[].attributes.definition
Water potential is the potential energy of water relative to pure free water (e.g. deionized water) in reference conditions. It quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, or matrix effects including surface tension.

# data[].attributes.note
Reused Water potential (Surface water): https://sms-cv.helmholtz.cloud/sms/cv/api/v1/measuredquantities/330/
Can also be measured in soils as information for e.g. plant physiology.