Organic Nitrogen

Nitrogen compounds within a soil in organic form, including amino acids, chitin, peptides, and proteins, being components that arise from dead bacteria, fungi and invertebrates, as well as form root exudates and dead roots, along with any applied organic material as part of a top-dressing. The nitrogen is only made available (as inorganic nitrogen) to plants following breakdown of the compounds as part of the mineralisation process by micro-organisms. Nearly all nitrogen within a soil is held as organic nitrogen.

  Organic Soil

This includes a range of soil classifications, depending upon the relative proportion of organic matter, degree of humification and moisture content. Soils that are wet will have low rates of decomposition and this results in a build-up of organic material, resulting in bogs or fens, both being peats. Organic soils will typically have a depth of at least 400mm and provide a mechanism to capture and store significant quantities of carbon dioxide, helping to mitigate climate change, and also storing vast quantities of water helping to reduce flood risk. The percentage of organic matter withi

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  Outfall

A point of discharge of water from a drainage system. Where an outfall discharges into a ditch, stream or river, it will have to be in accordance with water authority requirements. This will typically consist of a concrete structure with a splash plate to prevent erosion of the watercourse embankment.

  Over Acidic Soil

A soil which has a negative impact on the growth of a plant. In a turfgrass situation, an over acidic soil will lead to a thin sward; a more easily worn surface; weaker grass growth; an increased thatch layer, and an increase in drought susceptibility.

  Oxidation

A chemical weathering process, which is a reaction process in which minerals, or elements, gain an oxygen molecule, through the exchange of electrons during the process of combining with oxygen. A common example is that of iron reacting with oxygen to form rust (iron oxide), with decomposition of organic matter also being an oxidation process. The typical process would occur as follows: • Oxygen in the soil profile reacts with minerals or elements in the soil. This can be enhanced by the activities of oxidising soil micro-organisms. • Chemical changes occur, with the result being the form

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  Pan

A dense and often solid layer of soil which limits the infiltration and percolation of water. Pans can be caused by compaction, the filtering down of fine clay particles to form a distinct dense layer, or the reaction of elements such as iron or sodium to form a solid mass within a soil profile. This term is more typically referred to as a soil pan, clay pan, or hardpan.

  Particle Density

The solid mass of dry soil particles in a specific volume. This measure excludes any air pores and can be considered as a solid block of a material. It is expressed as the measure, grams per cubic centimetre.

  Particle Size Distribution

The total of the percentages, by weight, of soil particles of clay, sand and silt within a soil sample, with the different proportions of each soil particle size being quantified and contributing to the whole, which adds up to 100%. The particle size distribution is essentially the soil texture with the added accuracy of a breakdown of particle size proportions being given. An example, which is a sandy loam, is: • 60% sand (2mm ¯ 0.0625mm) • 25% silt (0.0625mm ¯ 0.002mm) • 15% clay (<0.002mm). For turfgrass situations the sand classification is normally ide

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  Passive Capillary Drainage

Narrow diameter rope, typically with a fibreglass outer covering and inner stainless-steel mesh forming a drainage tube. It is installed into an existing surface, such as a golf green, by being pulled through the soil profile, using a specially adapted type of mole plough with the cut slit being sealed afterwards with an attached roller which re-firms the surface. The drainage rope is installed at a depth of about 250mm, up to 600mm (for example at the Mere Championship Golf Club, https://themereresort.co.uk/blog/maintaining-a-championship-golf-course/, accessed 19th November 2022), and at a s

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  Peat

Partially decomposed organic material that was previously been used within a mineral top-dressing material to aid moisture and nutrient retention. With the exploitation of peatlands over the years their viability has become threatened and it is increasingly unacceptable to use peat within any mixture for the maintenance of sports and amenity turf surfaces. The minimum percentage of organic matter within a soil organic layer for it to be classified as peat varies according to different authorities, but is typically either 20% or 30% as a minimum.