Hand Texturing

The rubbing of slightly moist soil between fingers and thumbs to estimate the general soil type: especially if it is sandy (having a gritty feel); if it is silty (having a silky and smooth feel); or clayey (having a sticky feel to it). See also Soil Texture.

  Headwall

A concrete, brick, or similar, wall which is built around a major drainage outfall pipe. The main aim of a headwall is to provide stability to outfall situations.

  Herringbone Drainage

A drainage system where the lateral drainage trenches and pipes are installed in a fishbone type pattern. A central main drain is connected to by the lateral drains which are staggered and alternate along the length of the main drain. The lateral trenches will typically join a central drain at an angle of about 60 degrees.

  Hooghoudts Drainage Equation

A scientific method for determining the spacing requirements of pipe drainage or sand-gravel slit drainage in a sports field situation.

  Humic/Humus Layer

Part of the Organic Horizon which consists of well decomposed plant material. A Humic/Humus layer would sit below a Fermentation layer, and above an A Horizon. t is also called the H Horizon/Layer/Zone.

  Hybrid Bearing Layer

Reinforced rootzone with inclusions added to aid pitch stability.

  Hydraulic Conductivity [1]

A measure of the rate of water flow, typically saturated water flow, through the soil. In very general terms this might be thought of as indicative of a soils potential drainage rate. Hydraulic conductivity (HC) is influenced by a number of different factors, including: • The water content of the soil. A drier soil will have a lower HC, with the soil typically needing to reach field capacity before any significant outflow of water is achieved. HC is at its maximum when a soil is saturated. • Water and soil temperature affect the rate of flow. A warmer water is more fluid (i.e. having a

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  Hydrolysis

A chemical weathering process by which water dissolves minerals releasing nutrients which can be taken up by plants from the soil solution. The process can be considered as taking place over a couple of stages, with the initial stage being that of water entering the soil and then working its way through the soil profile. During this stage the water makes initial contact with soil minerals which contain ions, primarily cations. With the presence of water now being in contact with the soil minerals the next stage is that of the water molecules breaking the bond between the different chemical

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  Hydrophobic

A material which repels water. Soils can become hydrophobic due to waxy coatings on the soil particles, which mainly arises from the decomposition of organic matter and fungal activity. Dry patch is a disorder of some turf surfaces which is caused by the affected area being hydrophobic, with the application of wetting agents helping to reduce the repellent nature of the soil.

  Hygroscopic Water

Water that has been absorbed from a humid atmosphere and which is held very tightly onto soil particles by adhesion, and which is not generally available for use by a plant. If a soil has dried and / or a plant has used all available water and this is the only water remaining within a soil then unless water is readily made available to a plant, or it is able to become effectively dormant whilst the dry conditions persist, then it will have reached permanent wilting point and will die.