2. Zeolite needs to be used through the sand its growing in. Done as part of soil prep preferably.
3. Organic material should have been blended through the top 200mm of sand along with the zeolite and clay.
4. Make sure no fertilisers are used in the summer. Its too hot. The fert isn't used well and wastes your money. What is taken up leaves the lawn prone to burning and high water needs with shallow roots.
The overall problem comes back to the type of soil prep done which has, unfortunately, set you up for much of this. it creates an unfavourable environment for healthy microbes to flourish. They are what make plants grow (its not fertiliser)
Adding clay and zeolite is of far greater benefit than adding lawn mixes. I am not a fan of lawn mixes and would never use them myself. I wish they were not sold.
So how to sort your issue.
Well the first is to apply a wetting agent. Not just any either. Many popular brands are not as good as we are led to believe. I'd use Saturaid, Yates Soil Saturator or Baileys Grosorb.
Add some clay.
A 10kg bag of clay cat litter from my local Coles costs $6. It's not expensive.
Trufeed Bentonite will cost you $15-$20 from a stockfeed place
or SandRemedy or "Sand to Soil" are the RollsRoyce of Bentonites at higher prices.
A bag of zeolite across each area. $20 a bag.
Apply molasses (see the thread on it here at Homeone)
Every two weeks for a while.
Seasol or a seaweed product will be of a benefit.
A fish product like Charlie Carp or Powerfeed will also be of great benefit.
Under no circumstances apply a fertiliser.
Clearly, enough water is being applied. However the lawn has no capacity to obtain the moisture which would point the finger at a nasty fungus preventing the feeder and hair roots from having a drink when needed.
Make sure the retic is working with even coverage. Preferably, MP rotators should be used rather than junk popups which cost you more tp run than MP's cost to buy.
Top dressing with an actual organic compost. (Not lawn mix, lawn top dress or landscape mix, but an actual compost.)
Nick Bell would be one of the best to consult on this further. Alternatively, speak with The Garden Whisperers.
PM me for more
Cheers Fu, Good to see your back posting again.
When the front lawn when down, I could only get the Bentonite and zeolite thrown down as the landscaper was contracted.
The back lawn I did and followed your guide, I added all the additives Bentonite etc.. I have MP Rotators out the back, normal out the front.
I first started to notice the damage lawn in Sept/Oct, there was small yellow spots all over the lawn ( back and front ) This was when there was still heavy rain about. Which is why i thought it wasnt a water issue. Eventually these spots become bigger and then looked like large brown patches.
I also used a wetting agent in Dec.
Today I put down organic compost from " Green Life Soils, Midvale " and watered it in. Sprayed with Seasol. So hoping this will become green again.
Nath