Clay Soil under new turf

[aks476]

Help!!
I layed approximately 150m2 of ST 26 Buffalo in Sept of 2009. I removed all existing turf and topsoil with bobcat and layed 50mm of organic turf underlay. The day before laying turf huge winds removed the majority of underlay from one section of yard that is predominately a clay base. I raked as muched as I could back over and layed my new turf.
Everything was great until about march/april when this front section of lawn started to yellow and slow down. I have dug a small area up and found only about 2 inches of soil before hard clay. Can I treat this clay base successfully now after lawn has been laid and established? I was thinking of coring my new then maybe spreading gypsum any advice would be appreciated !!

[Steve]

G'day,

That really does sound like a problem - and any solution isn't going to be simple.

Barring pulling the turf up to treat the clay - there really are few options except to make the best out of the situation and keep doing all the right things, even if they are only small.

Lawn coring will help - but it's effect will be limited, the tynes aren't supposed to go too deeply into the soil so you're not going to get into the clay too much, but the holes will of course aid in getting the gypsum deeply into the soil profile than if you didn't do it at all. Wetting Agents should also be applied to aid in water distribution in the soil profile too.

You may want to keep repeating the Coring / Gypsum / Wetting Agents routine a couple of times a year for a few years as regular maintenance.

Also, if the tynes don't reach right into the clay base, then there's really no reason to add a sandy filling to aid the drainage - because you already have the top soil in place which should be free flowing.

The last thing would be to keep looking after the lawns health. Ensure adequate water, and put down a quality fertiliser every 2 months to manufacturers recommendations.

You could also buy a very high quality organic lawn top dressing soil - this will give a great amount of nutrients to the turf to keep it healthy - and to help counter balance the bad effects of the clay. This type of top dressing only needs to be put on very thinly - and is usually raked into the green leaf and thatch - leaving only a small amount of residue on top of the lawn. This doesn't need to be done at the same time as Coring and doesn't need to fill the coring holes.

Hope that helps to get you started with things - like I said, there's no easy solution, just good ongoing cultural management practices.