Science - June 22, 2012

At last, a good grass carpet in Arena, the Wageningen way

The Amsterdam Arena football stadium has the best grass carpet in the Netherlands, declared the captains of the premier leagues recently. Fifteen years ago, the grass carpet was in fact a disaster, with turf flying all over. The analysis given by the Wageningen agrotechnologist Willem Tonk in 1996 was the basis of this comeback.

Assimilation lighting in the Arena
At the handing over of the Amsterdam Arena in 1996, its architects had not envisaged the 'grass' problem in the stadium. The grass carpet had to be replaced four or five times in the first few seasons because the grass did not grow well. Engineering firm Heidemij, which laid the grass carpet, turned to Wageningen experts for help. The company received unsolicited advice from the analyst Willem Tonk, who was a bit of a Willy Wonka character in Wageningen in those days. He described the problem faced by the grass carpet in the predecessor of Resource and subsequently, in the Volkskrant.
The grass had too little air and light, Tonk pointed out. He also provided sketches of a technical installation which would solve this problem in the stadium by using reflective curtains to reflect light, and enormous pipes to siphon off the high carbon concentration above the grass. Although this Willy Wonka design was never implemented, it opened the way for the eventual installation of assimilation lamps in the stadium. This decision was made by the Amsterdam Arena based on advice from Wageningen UR and Philips. The grass now grows like never before.
'Tonk hit the nail on the head fifteen years ago,' says Wageningen grassland expert Egbert Lantinga. 'There was not enough light in the stadium. If grass gets too little light, it puts all its energy into the leaves, while its roots will not develop. That was why grass suds flew all over the place.' It was only four years ago that the Amsterdam Arena solved this problem once and for all. Assimilation lighting was introduced - artificial lightig is now hung above the grass carpet in between matches. The PSV stadium does the same too. Previously, the roof and doors were opened often to dispel the moisture above the grass more effectively.
Tonk, who has stopped working for the university in the meantime, is pleased to explain all over again. 'The problem is a photomorphogenetic one. It has to do with ultraviolet light which switches on something in the plant, enabling better root growth. The roof of the stadium keeps this UV light away.' While assimilation lighting uses lamps to provide UV light, there is a cleverer and much cheaper way, says Tonk. 'Philips has TL lamps which produce a lot of ultraviolet light. Build these lamps into the stadium's lawn mower. Two minutes of UV light a day is all that's needed for good root forming.'
It seems that Wageningen grass and material experts and football stadiums are made for each other. Lantinga was advisor during the construction of the San Siro stadium in Milan a long time ago. Tonk himself had given advice to the contractor responsible for the Gelredome in Arnhem. Not about grass in that case, since the grass carpet in the Vitese stadium is rolled up and given enough light outside the stadium. It was about the rubber parts in the rolling system - Tonk is a master of all trades.