After a severe drought, my clay based soil wont grow any grass, help please :-(

[OnTheGrass]

Last year we had a 1/1000yr drought, it created 3"+ retraction from the borders and concrete and lightning style cracks 1"+ wide across the small 70sqm Kikuyu lawn. Our house also saw the effects with minor cracking in our plaster walls etc due to the settling of the earth, for the most part the autumn and winter has returned all back to normal, but in certain patches, no matter what we do, grass just wont grow, we have turned over the patches, put turf/compost mix over the patches, laid seed, covered with anti bird stuff, watered it as required and only a few sprouts, to the other side it seems to have grown back fine, but still the soil looks grey, not a nice dark colour.

So I think the soil is the issue here? Its also on reactive clay. I do not know how much quality soil was laid for this small 70sqm lawn, but I suspect not much if any and what it is growing on is reactive clay I am not sure. After a week of rain, the sun will turn the bare patch areas into near stone like when you tap them with your knuckles, it is a grey colour.

So Im thinking a clay breaker and soil conditioner and possibly top soiling the small yard?

Here is a pic of the worst area to the side of one part of the decking. Please help, any positive intent suggestions welcomed. Thank you in advance.

Just note: I have scalped the lawn (was going to apply dethatcher but seems I dont need it), where it does grow it is a nice deep green colour at about 50mm+, this is 30mm. Excuse the distortion of the wideangle lens from my phone.

 

[cpurvis]

You didn't say where you live. I would contact the county agriculture agent and get their recommendation. If you don't have one, I would try this:

1. Remove the top 6" of the clay soil and replace it with black dirt and a sprinkler system.

or

2. Deep-till in sand to increase the porosity of the clay, add as much black dirt on top of that as drainage permits and install a sprinkler system.