Why is the Olympic hockey field wet?

Answer 1

There "appears" to be a spray because in fact there is a spray. All games at the Beijing Olympics hockey tournament were played on the wet base artificial turf specially laid for the tournament. These turfs are covered with a small amount of water before (and somtimes redone at halftime of) each game, in order to help lessen the effect of injury on it and alow the ball to move quicker than if the turf was dry.

Answer 2

An infill is used on an artificial hockey turf to help keep the pile upright and decrease wear and tear on the carpet. Water is used as an infill at national and international levels, as it allows more consistancy in ball roll and bounce, free movement of the pile, and more shock absorbance and less abrasiveness than earlier sand-based turfs. Sand-based or hybrid turfs are still used at local and regional levels because water-baesd turfs are more expensive to install and maintain.
London 2012 will be the first world event to be played on a different coloured synthetic turf to the traditional green.

The water-based surface uses a high-performance polyethylene resin helping to make it the world's fastest pitch.