3:4:5 Triangle

A triangle with sides of a specific ratio of 3 units to 4 units to 5 units produces a right-angled triangle. This triangle is used to start setting out any sports pitch which has right angles within it.

  Abiotic

The non-living elements of an ecosystem. Examples include soil minerals, temperature, water, light, air and soil chemicals.

  Abiotic Stressor

A wide range of natural, non-biological causing, effects that can influence the behaviour of a plant.

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  Above Ground Biomass

The total weight of plant shoots, in particular leaves and sheaths for grasses. For research purposes this would normally be the total dry weight of shoots.

  Abrasion

The process of wearing something away. For example, the use of solid or slit tines are prone to abrasion especially within a soil with a high percentage of sand particles. This is often the main reason why the length of tines reduce over time with regular use and replacement tines need to be planned for.

  Absorption

The movement of water or nutrients in solution from a soil into the internal domain of plant cells.

  Acclimatisation

The process whereby a plant, or other organism, adjusts their ability, over a short period of time, to survive changes which has occurred in its local environment. Plants, for example, which are gradually exposed to increasing or decreasing temperatures will adjust much better than plants will are suddenly exposed to a rapid change in temperature.

  Accuracy

How close a measurement is to its true value. For example, a soil pH meter used in the field might record a measurement of 6.5, yet the true value, which was obtained from a laboratory test was 5.8. This example would not be considered very accurate but might be considered helpful in giving a general indication of soil pH as it is within say 1 pH unit. However, if the true value was 4.5 but the recorded value was 5.4 then this could have much more significant implications for material inputs and maintenance decisions, so the degree of accuracy may or may not have significant implications for t

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  Acervulus

A fungal fruiting body which has very fine and short, blackened hairs, from which spores are released. Anthracnose is a common disease of turf in which these structures are present. Acervuli is the plural form.

  Acid Equivalent

The theoretical amount of the original (or parent) chemical compound (i.e. acid) within the formulated active ingredient component of a pesticide. A parent acid is made into another formula (resulting in the term active ingredient) by combining with some other elements, and this is called a derivative, often term salt of [compound name], or ester of [compound name]. The different derivatives of a pesticide will have different concentrations of the original chemical compound within it; the higher the concentration within the derivative the higher the acid equivalent. The term is often shortened to AE.