Silt Loam Soil Class

A soil with a high percentage of silt, along with high quantities of sand and medium quantities of clay. An example of a silt loam soil is one that contains the following: 5% sand, 82% silt, 13% clay. It can compact very easily, yet does retain nutrients and water well, so for general landscape areas this might be suitable, although usage on slopes may be inadvisable due to potential stability issues with high silt soils.

  Silt Soil Class

This soil contains a very high amount of fine silt particles, being smooth and silky to touch and is especially powdery when dry as the particles do not hold together well like a clay soil does. An example of a silt soil is one that contains the following: 10% sand, 85% silt, 5% clay. A silt soil can retain nutrients and water and is often present in river valleys, being more noticeable on flood plains and areas that are temporarily flooded from overflowing rivers. There is not a stand-alone silt textural class in the UK Soil Textural Triangle as this is all enclosed within the silt loam class.

  Silt Trap

An inspection chamber within a drainage system. The chamber allows soil sediment, that is suspended or contained within drainage water for a period of time, to settle in the base of the chamber. Less contaminated water will eventually be discharged in the outflow pipes once the height of those pipes has been reached. It is important to periodically inspect and clean out silt traps, otherwise sediment will build-up and clog up the drainage system, making it ineffective. It is also called an inspection chamber.

  Silty Clay Loam Soil Class

A relatively heavy soil that is not suited for turfgrass situations and is poor for general landscaping as well. An example of a silty clay loam soil is one that contains the following: 15% sand, 50% silt, 35% clay. The soil can retain nutrients and moisture well but will be difficult to work for much of the year when it is wet and drying hard and providing a surface cap during hot dry weather.

  Silty Clay Soil Class

A soil with a high percentage of silt, along with high percentage of clay and low percentage of sand. An example of a silty clay soil is one that contains the following: 10% sand, 45% silt, 45% clay. Not a soil for amenity or sports turf areas, but for damp landscapes wishing to encourage specific wildlife and vegetation then this will be ideal because water and nutrient retention will be high.

  Slit Drain

A narrow channel formed into a turf surface to aid the removal of surface water to sub-surface drains. The slit may be formed by excavating soil and filling with sand or sand overlaying gravel, or similar coarse aggregate material. It may even have sand injected into a channel without soil excavation.

  Slit Drainage

A drainage system consisting of one or more slit drains.

  Smectite

A 2:1 layer clay mineral. It is typically produced following weathering of basic rocks and often results in poorly drained soils with alkaline soil pH.

  Smile Drain

A lateral drain laid in the shape of an arc, resembling the curve line of a smile, which (where installed) is located at the lowest points of a golf green, and which is typically the front of a green as well, but may also be at other perimeter areas.

  Soakaway

An excavated hole, or pit, which has been filled with porous material, such as gravel or stones. Drainage water is channelled into the soakaway using drainage pipes. The aim of this is for collected water to gradually drain away into the surrounding soil and sub-layer. This negates the need for an outfall.