Hollow Tine 
A hollowed out metal cylinder, with part of one side wall being open to allow the removal of soil cores when the tine penetrates into the soil. Hollow tines are used for removing thatch, soil exchange and to relieve soil compaction. This type of tine is sometimes also referred to as a Corer.
Hollow Tining
The action of using hollow tines to aerate a soil. This activity can also be referred to as Coring.
Horsepower
A unit of measure for work rate, primarily of an engine, in relation to that produced by a horse, and is used to express the power that can be produced. One mechanical (or imperial) horsepower equates to 0.746kW, whilst a metric horsepower equates to 0.735kW, although there are other different horsepower measures. The mechanical horsepower is probably the most common one to use, although there is only about 1.5% difference between them and from a turf management perspective this has little practical difference or meaning. For example, a 50 hp tractor would produce either 37.3kW or 36.75kW depending on the conversion type used.
Hover Mower
A rotary mower which creates a downward force to provide a cushion of air beneath its chassis. This enables it to hover and effectively glide just above a turfgrass surface. There are, therefore, no wheels or cylinder to provide contact with the turf surface, because it is floating on a cushion of air.
Hydraulic Nozzle
A nozzle, such as flat fan or hollow cone etc, through which a liquid spray is forced under pressure, creating a range of droplet sizes.
Hydroseeding
The application of grass or wildflower seed, which is mixed with water and sprayed onto a soil area. Included within the mixture might also be a fertiliser or a liquefied mulch. This technique can be useful on relatively steep slopes and areas which are prone to erosion.
Impact Mower
A flail or rotary mower which cuts grass through the physical impact of their blades; in contrast to the shearing cutting motions of cylinder and reciprocating knife mowers.
Interseeding
In the USA this term is used to refer to the action of applying grass seed to an area. It is used in the same context as that of Overseeding within the UK.
Irrigation
The planned and controlled application of water to a surface. Water can be applied through a range of different items of equipment, ranging from a watering can, hose pipe, static sprinkler, self-travelling sprinkler, or automatic pop-up sprinkler.
Jargon
Specialist words or terms that are used to help professionals reduce the chance of confusion and increase efficiency of communication with each other.
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