Soil Nitrogen Supply (SNS)

The net amount (after losses for example through leaching or volatilization) of nitrogen available to plants within the soil over the year. A natural reserve of nitrogen made available by the nitrogen cycle to a turfgrass area might be in the region of 40 kg/N/ha/yr. Fertiliser applied nitrogen would then be added to maintain a suitable hard-wearing sward.

  Soil Organic Matter

All dead and decaying organic material which is present within a soil. In a soil this might be thatch, digested material within earthworm casts, or any organic remains of plants and soil fauna. The term is sometimes also referred to as Soil Organic Material.

  Soil Organisms

Any living organism within a soil. These are also called Soil Fauna ranging from bacteria up to moles. They can be categorised according to size into Microbiota (Microfauna and Microflora); Mesobiota or Mesofauna, and Macrobiota (Macrofauna). Soil organisms have an essential role to play within soil ecology and promote a healthy soil environment.

  Soil Particle Analysis

A physical assessment of the size range of the soil particles within a sample of soil. Also called Particle Size Analysis.

  Soil Permeability

The ability of a soil to allow water and air to move through it. A soil with good permeability will typically be well aerated and have good drainage properties.

  Soil pH [1]

See pH.

  Soil pH and its Influence on Plant Growth

The main influence that soil pH has on plant growth is that of limiting the ability of plants to grow and develop within a range of pH values, depending on how well adapted they are to certain levels of acidity, or concentrated of hydrogen ions within a soil. In addition, micro-organisms (especially soil bacteria) which help decompose organic matter, thereby releasing stored nutrients, are affected by soil acidity, being less active and present, in general, the acidic the soil. The second major factor is that the extent of acidity influences the availability of nutrients within a soil, whe

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  Soil Porosity

The space or gap between the mineral particles within a soil. Pore space will be filled by either air (which is technically called Air Filled Porosity) or water (which is technically called Water Filled Porosity), with roots and soil fauna also making use of the pore spaces. Soil porosity is usually expressed as a percentage of the soil volume. The theoretical maximum soil porosity for uniform particles is about 50%, although in practice the soil porosity for turf surfaces will be significantly less, may be in the region of 15% to 35%.

  Soil Profile

A vertical section of a turf surface and rootzone. It will typically show more than one soil horizon, especially the surface organic layer, known as thatch, as well as topsoil or main rooting medium, and may be sub-soil where present. A good depth for analysing a soil profile will be from 150mm to 300mm, but this will depend upon the circumstances and requirements of the soil profile. A soil profile will often be able to provide an indication of soil structure, root growth and soil fauna activity.

  Soil Structure

A description of how soil particles are arranged, or clumped together, into aggregates. The pore space within an aggregate and between aggregates is an important aspect of soil structure. A well-structured soil will generally provide good growing conditions, allow for good root growth, improved drainage and a drier surface. Poorly structured soils will provide the opposite of beneficial conditions, including poor drainage, waterlogged surface, poor root growth and increased match cancellations of games where sports are played on the area. There are different types of distinct structural units called Peds within a soil.