Rolling Resistance

The distance a ball rolls along a surface. The ball is released from a specially constructed ramp, and the friction of the particular surface the ball is rolling over offers resistance, to slow the ball down. Also called Rolling Distance, or Ball Roll.

  Root Depth

A structural quality performance standard which states the minimum depth of root growth, in millimetres. This actually only measures the depth of root penetration and not the quantity of roots of root mass, so a single root would actually meet this criterion. The standard could be qualified to state that a minimum of say 10 roots must be measured at this desired depth.

  Rootzone Medium

A structural quality performance standard which states the minimum depth of growing medium (i.e. suitable top-soil or specially imported material), in millimetres.

  Rootzone Particles

A structural quality performance standard which is suitable for cricket pitches and tennis courts and which is split into two parts: the first is Clay content, which states the minimum amount of clay particles, as a percentage, in the soil; whilst the second part is the Total quantity of soil particles below 0.125mm in diameter, as a percentage, in the soil.

  Rootzone Silt & Clay Content

A structural quality performance standard which states the maximum amount of silt and clay particles, as a percentage, within the rootzone medium. A minimum figure might also be included to ensure the hydraulic conductivity of a profile is not excessive, which can be particularly important when using these performance standards as guides for construction work.

  Soil nutrient level

There are two structural quality performance standards for this, both being measured as an Index figure: one which indicates the amount of extractable phosphate (P2O5) and one which indicates the amount of extractable potash (K2O), both using acetic acid. However, the readings may be understood to relate to the ADAS Indices which actually states figures in P and K, with the Olsens P method being used for P and Ammonium nitrate extract for K.

  Soil pH [2]

A structural quality performance standard which states the desirable pH range for the particular surface.

  Soil Strength

A structural quality performance standard which states the minimum strength of a soil, measured in kilogrammes, to prevent it breaking under that weight. The figures may also be given as a range, for example, 60kg ¯ 70kg.

  Spin [1]

The action imparted by a player onto a cricket, tennis or golf ball in particular. Spin is used in cricket and tennis as a means to deceive an opponent with the ball often changing direction from the perceived direction of travel once it makes contact with the ground. Backspin on a golf ball is used by a golfer to control the ball once it makes contact with the green.

  Spin [2]

A playing quality performance standard which states the extent of deviation, in millimetres, from a straight line during the delivery of a ball.