Subcategories


 

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S x E x M

Expression used to indicate that there are intricate interactions between soil properties i.e. diagnostic features (intrinsic and dynamic ones), environment (climate, weather, slope, etc.) and management (the analogue from crop production is G (genotype) x E x M), acknowledging that soil functions are never uniquely determined by just one of these three factors.

Saline soil

A non-sodic soil (see sodic soil) containing sufficient soluble salt to adversely affect the growth of most crop plants. The lower limit of electrical conductivity in the saturation extract of such soils is conventionally set at 4 dS m-1(at 25

Saline-sodic soil

Salt-affected soils with a high exchangeable sodium percentage (ESP) greater than 15%, pH usually less than 8.5; in general these soils are not suitable for agriculture.

Salinization

Accumulation of soluble salts (more soluble than gypsum) in the upper soil layers (saline soil = soil containing enough soluble salts to negatively affect most crop plants, commonly 4000

Salt-affected soil

Soil that has been adversely affected by the presence of soluble salts, with or without high amounts of exchangeable sodium. See also saline soil, saline-sodic soil, and sodic soil.

Sand

Soil particles being 0.06-2.0 mm in diameter with low specific area OR a soil textural class with 65% or more sand and less than 8% clay. Unlike clays, sandy soils do not shrink and swell on drying and wetting and, unless artificially compacted, are rapidly permeable. (NB: USDA classification uses 0.05 instead of 0.06).

Saprophytic fungi

Fungi that decompose dead organic matter.

SAR

Sodium Adsorption Ratio (mol/m3)^0.5.

Saturated zone

Subsurface area below unsaturated/ vadose zone that is permanently water-saturated.

Scoring function

A standardization procedure used to convert measured values or subjective ratings to unitless values usually between 0 and 1. This allows all soil property measurements to be integrated into one value or index for soil quality. The four general types of scoring functions used in soil quality assessments are: more is better (higher measurements mean higher soil quality, e.g. SOM); less is better (lower measurements mean higher soil quality, e.g. salinity); optimum range (a moderate range of values is desirable, e.g. pH); undesirable range (a specific range of values is undesirable)


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