Sustaining grass under leylandii

Hello

I have probably just wasted £50 buying turf to lay under the leylandii.  I wish had taken the time to understand the cause for the dying, dead and absent grass before taking the time to lay the turf.

So, what have i learned today?

1.  Leylandii is pretty much a death sentence for most things, due to them sucking all the nutrients out of the soil.

2. Hose-loving Flat-coated Retrievers double the time it takes to lay turf, but refuse to help dig the soil.

Now I need to know if there is anything I can do keep the new grass alive.

I did not add anything to the soil before I laid the turf on it.  I simply dug it, turned it, levelled it, soaked it, then rolled the turf out and soaked that too.

That has worked for me in the past. I doubt it will work in this case.

The lawn is a couple of feet higher under the huge leylandii, presumably from years of bits falling off the trees and piling up.

Interestingly when I dug the soil it was horribly dry and dusty and the spade easily sunk through it.  When I soaked the soil it seemed almost hydrophobic.

Is there anything I can add to the soil, or feed the grass with, to  keep the lawn alive?

At my disposal I have a garden waste bin half full of thoroughly decomposed grass clippings, and miles of bridleways with what looks like an unlimited lifetime supply of manure.

Any good for this job, or do I need something more specialised?

Thanks

Mark