“In the first year when the training pitches were delivered, five years ago now, nobody could have foreseen how badly the grass would grow. There were a lot of bare patches of grass, especially near the overlap of the sprinklers,” explains says the groundsman, who manages the training fields. After the first season, 2 cm of the grass layer was milled off with a fieldtop maker, reseeded and fertilised. Due to the hot and dry summer the following year, the emerging grass burned immediately. Uitentuis: “We wondered what was causing this and started looking. We found out that it had to do with the salinity in the irrigation water. With this knowledge, we started spraying the fields much more to push away the salt, sometimes as much as 40 to 50 ml/m2 per night. Normally we give between 10 and 15 ml/m2 depending on the time of year.”

Grass is greener at AZ Alkmaar

Getting the ball to roll faster

After a large amount of water, there was no watering for a few days until the turf dried out. That was the moment to start watering again. “As a result, it took longer than desired, also from the club’s point of view, before there was a reasonable grass surface. But at the overlap spots of the sprinklers we saw that the grass didn’t want to grow because of the salinized soil,” explains Uitentuis.

The search for innovative irrigation technology

In order to remove the salt from the irrigation water (with an EC of 7.0), a Reverse Osmosis system was considered. But this system could not handle the amount of water from the pump, which has a capacity of 60 m3/hour. Tap water was not an option either, because there was no adequate connection to be made, and using drinking water would be expensive.

Two years ago, the groundsman called in Westhoven Agro Advies who put him in touch with AQUA4D® BeNeLuxDu importer Lescrauwaet BV in Hilversum for treatment of the surface water. With the AQUA4D® water system, the irrigation water is treated with resonance fields, which improves or refines the structure of water clusters.

According to the groundsman, this watering system has the required capacity, is affordable, and has a positive effect on bare grass areas. “The water surface tension is lower, so the water droplets are smaller and less spherical. We can also see this in the water that is sprayed more when watering the grass. Due to the change in water clusters, the water droplets no longer remain on the leaf. Because they roll off, we also no longer have any salt residue. As a result, the grass no longer burns.”

A new approach to water management

The AQUA4D® system has made a significant difference to the grass patches that refused to grow. “Every year is different here – it can be warmer or colder, more or less sunlight and drier or wetter. Water is one facet of the whole picture, but the most important one. In summer, we now have a different fertilisation policy with more coated fertilisers, which are released slowly, and we spray urea fertiliser on the leaves,” says Uitentuis.

“We are pleased with the beautiful green turf this summer. It really is a picture,” he concludes.

Find out more about sustainable water management for football: https://www.aqua4d.com/news/sustainable-football-irrigation/