Sodium Chloride 
The chemical name for common salt and this is found in relatively high concentrations in coastal soils.
Sodium Nitrate
An inorganic source of nitrogen which produces an alkaline reaction in turf and can also deflocculate a soil if used regularly. It also produces soft, weed and disease prone surface. It contains 16% nitrogen.
Soil Index
The concentration of a nutrient that is available for uptake by a plant within a soil. A soil test (with difference methods being used by different organisations) determines how much of a nutrient can be extracted from a soil. The main nutrients of phosphorus, potassium and magnesium have indices that categorise availability from inadequate to excessive. England, Wales (Defra)and Northern Ireland (Daera) use Indices with 10 bands (0-9), whilst Scotland uses the SAC soil nutrient status, which is a descriptive scale of 6 categories (Very low; Low; Moderate-; Moderate+; High; Very High), whilst
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Soil Mineral Nitrogen
An expression which relates to the Nitrogen in the form of ammonium and nitrate held within a soil.
Soil Nutrient Testing
This is an important activity prior to applying fertilisers. It helps to determine the availability of nutrients within a soil and this would then be used, along with other soil tests, such as pH, organic matter content and soil texture, as well as knowing the type of sward required and desired grass species, the type and formulation of fertiliser that would be best suited for the situation.
Having an understanding of the available plant nutrients within a soil, whether macro-nutrients or micro-nutrients, can help determine if there is a deficiency, adequate amount, or excess (which can lea
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Soluble Fertiliser
A fertiliser which can be dissolved in water. Increasing water temperature increases the rate and extent of dissolution. Liquid fertilisers or foliar sprays are made from soluble fertilisers.
Solution Fertiliser
A fluid fertiliser that is free of solid particles.
Straight Fertiliser
A fertiliser which provides a single, typically one of the main plant nutrients of Nitrogen, Phosphorus or Potassium. A straight fertiliser may be used as a fertiliser to provide a targeted amount of specific nutrient. Two or more straight fertilisers may be mixed together to create a more balanced fertiliser.
Sufficient Level of Available Nutrient
This is a method of estimating the response of a plant to nutrients available within a soil. It aims to identify the minimum amount of fertiliser, especially phosphorus and potassium as primary nutrients, but also including a range of other nutrients, needed to achieve optimum turfgrass performance, not to maximise turfgrass growth. Within an agricultural context this would relate to maximising profitability.
Sulphate of Ammonia